Publications by authors named "Olga A Dontsova"

82 Publications

Antibacterial activity of noscapine analogs.

Bioorg Med Chem Lett 2021 Apr 21;43:128055. Epub 2021 Apr 21.

Department of Chemistry and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia; Center of Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143026, Russia; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 142290, Russia.

The antibacterial properties of close noscapine analogs have not been previously reported. We used our pDualrep2 double-reporter High Throughput Screening (HTS) platform to identify a series of noscapine derivatives with promising antibacterial activity. The platform is based on RPF (SOS-response/DNA damage) and Katushka2S (inhibition of translation) proteins and simultaneously provides information on antibacterial activity and the mechanism of action of small-molecule compounds against E. coli. The most potent compound exhibited an MIC of 13.5 µM(6.25 µg/ml) and a relatively low cytotoxicity against HEK293 cells (CC = 71 µM, selectivity index: ~5.5). Some compounds from this series induced average Katushka2S reporter signals, indicating inhibition of translation machinery in the bacteria; however, these compounds did not attenuate translation in vitro in a luciferase-based translation assay. The most effective compounds did not significantly arrest the mitotic cycle in HEK293 cells, in contrast to the parent compound in a flow cytometry assay. Several molecules showed activity against clinically relevant gram-negative and gram-positive bacterial strains. Compounds from the discovered series can be reasonably regarded as good templates for further development and evaluation.
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http://dx.doi.org/10.1016/j.bmcl.2021.128055DOI Listing
April 2021

Synthesis and Biological Evaluation of PSMA Ligands with Aromatic Residues and Fluorescent Conjugates Based on Them.

J Med Chem 2021 Apr 6;64(8):4532-4552. Epub 2021 Apr 6.

Chemistry Department, Lomonosov Moscow State University, Leninskie Gory, Building 1/3, GSP-1, Moscow 119991, Russian Federation.

Prostate-specific membrane antigen (PSMA), also known as glutamate carboxypeptidase II (GCPII), is a suitable target for specific delivery of antitumor drugs and diagnostic agents due to its overexpression in prostate cancer cells. In the current work, we describe the design, synthesis, and biological evaluation of novel low-molecular PSMA ligands and conjugates with fluorescent dyes FAM-5, SulfoCy5, and SulfoCy7. evaluation of synthesized PSMA ligands on the activity of PSMA shows that the addition of aromatic amino acids into a linker structure leads to a significant increase in inhibition. The conjugates of the most potent ligand with FAM-5 as well as SulfoCy5 demonstrated high affinities to PSMA-expressing tumor cells . biodistribution in 22Rv1 xenografts in Balb/c nude mice of and conjugates with a novel PSMA ligand demonstrated good visualization of PSMA-expressing tumors. Also, the conjugate demonstrated the absence of any explicit toxicity up to 87.9 mg/kg.
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http://dx.doi.org/10.1021/acs.jmedchem.0c01935DOI Listing
April 2021

Bioprospecting of Soil-Derived Actinobacteria Along the Alar-Hotan Desert Highway in the Taklamakan Desert.

Front Microbiol 2021 15;12:604999. Epub 2021 Mar 15.

Department of Microbial Chemistry, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.

Taklamakan desert is known as the largest dunefield in China and as the second largest shifting sand desert in the world. Although with long history and glorious culture, the Taklamakan desert remains largely unexplored and numerous microorganisms have not been harvested in culture or taxonomically identified yet. The main objective of this study is to explore the diversity, novelty, and pharmacological potential of the cultivable actinomycetes from soil samples at various sites along the Alar-Hotan desert highway in the Taklamakan desert. A total of 590 actinobacterial strains were recovered by the culture-dependent approach. Phylogenetic analysis based on 16S ribosomal RNA (rRNA) gene sequences unveiled a significant level of actinobacterial diversity with 55 genera distributed in 27 families of 12 orders. Thirty-six strains showed relatively low 16S rRNA similarities (<98.65%) with validly described species, among which four strains had already been characterized as novel taxa by our previous research. One hundred and forty-six actinobacterial isolates were selected as representatives to evaluate the antibacterial activities and mechanism of action by the paper-disk diffusion method and a double fluorescent protein reporter "pDualrep2" system, respectively. A total of 61 isolates exhibited antagonistic activity against the tested "ESKAPE" pathogens, among which seven strains could produce bioactive metabolites either to be able to block translation machinery or to induce SOS-response in the pDualrep2 system. Notably, sp. 16Sb2-4, harboring a promising antibacterial potential with the mechanism of interfering with protein translation, was analyzed in detail to gain deeper insights into its bioactive metabolites. Through ultra-performance liquid chromatography (UPLC)-quadrupole time-of-flight (QToF)-MS/MS based molecular networking analysis and databases identification, four families of compounds (-) were putatively identified. Subsequent bioassay-guided separation resulted in purification of four 16-membered macrolide antibiotics, aldgamycin H (), aldgamycin K (), aldgamycin G (), and swalpamycin B (), and their structures were elucidated by HR-electrospray ionization source (ESI)-MS and NMR spectroscopy. All compounds - displayed antibacterial activities by inhibiting protein synthesis in the pDualrep2 system. In conclusion, this work demonstrates that Taklamakan desert is a potentially unique reservoir of versatile actinobacteria, which can be a promising source for discovery of novel species and diverse bioactive compounds.
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http://dx.doi.org/10.3389/fmicb.2021.604999DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8005632PMC
March 2021

Multifaceted Mechanism of Amicoumacin A Inhibition of Bacterial Translation.

Front Microbiol 2021 12;12:618857. Epub 2021 Feb 12.

Petersburg Nuclear Physics Institute named by B. P. Konstantinov, NRC "Kurchatov Institute", Gatchina, Russia.

Amicoumacin A (Ami) halts bacterial growth by inhibiting the ribosome during translation. The Ami binding site locates in the vicinity of the E-site codon of mRNA. However, Ami does not clash with mRNA, rather stabilizes it, which is relatively unusual and implies a unique way of translation inhibition. In this work, we performed a kinetic and thermodynamic investigation of Ami influence on the main steps of polypeptide synthesis. We show that Ami reduces the rate of the functional canonical 70S initiation complex (IC) formation by 30-fold. Additionally, our results indicate that Ami promotes the formation of erroneous 30S ICs; however, IF3 prevents them from progressing towards translation initiation. During early elongation steps, Ami does not compromise EF-Tu-dependent A-site binding or peptide bond formation. On the other hand, Ami reduces the rate of peptidyl-tRNA movement from the A to the P site and significantly decreases the amount of the ribosomes capable of polypeptide synthesis. Our data indicate that Ami progressively decreases the activity of translating ribosomes that may appear to be the main inhibitory mechanism of Ami. Indeed, the use of EF-G mutants that confer resistance to Ami (G542V, G581A, or ins544V) leads to a complete restoration of the ribosome functionality. It is possible that the changes in translocation induced by EF-G mutants compensate for the activity loss caused by Ami.
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http://dx.doi.org/10.3389/fmicb.2021.618857DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7907450PMC
February 2021

Nybomycin inhibits both types of DNA gyrase - fluoroquinolone-sensitive and fluoroquinolone-resistant.

Antimicrob Agents Chemother 2021 Feb 16. Epub 2021 Feb 16.

Department of Chemistry, Faculty of Bioengineering and Bioinformatics and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.

Bacterial type II topoisomerases, DNA gyrase and topoisomerase IV, are targets of many antibiotics including fluoroquinolones (FQs). Unfortunately, a number of bacterial species easily acquire resistance to FQs by mutations in either DNA gyrase or topoisomerase IV genes. The emergence of resistant pathogenic strains is a global problem in healthcare, therefore, identifying alternative pathways to thwart their persistence is the current frontier in drug discovery. An attractive class of compounds is nybomycins, reported to be "reverse antibiotics" that selectively inhibit growth of some Gram-positive FQ-resistant bacteria by targeting the mutant form of DNA gyrase, while being inactive against wild-type strains with FQ-sensitive gyrases. The strong "reverse" effect was demonstrated only for a few Gram-positive organisms resistant to FQs due to the S83L/I mutation in GyrA subunit of DNA gyrase. However, the activity of nybomycins has not been extensively explored among Gram-negative species. Here, we observed that in Gram-negative ΔtolC strain with enhanced permeability, wild-type gyrase and GyrA S83L mutant, resistant to fluoroquinolones, are both similarly sensitive to nybomycin.
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http://dx.doi.org/10.1128/AAC.00777-20DOI Listing
February 2021

Cyanine mitochondrial dye with slightly selective cytotoxicity against A549 cancerous cells.

Arch Pharm (Weinheim) 2021 Mar 27;354(3):e2000281. Epub 2020 Nov 27.

Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.

Delocalized lipophilic cations (DLCs) are known as mitochondria-addressed molecules. Mitochondria targeting may provide opportunities for tumor detection. DLCs may have antioxidant or anticancer properties. In this study, we focused on the toxicity and localization of 2-[(E)-2-(5-fluoro-2-methyl-1H-indol-3-yl)ethenyl]-1,6-dimethylpyridin-1-ium iodide (62E2), which has recently been found as a novel cytotoxic fluorescent compound. The excitation maximum of 62E2 is 452 ± 10 nm and its emission maximum is 579 ± 10 nm. It is accumulated in the cells and stains mitochondria in nanomolar concentrations. 62E2 is cytotoxic and mitotoxic in low micromolar concentrations, and it demonstrates some selectivity of cytotoxicity against A549 cancer cells. The closest analog of 62E2 is F16, which is the fluorescent mitotoxic agent that has been described earlier as a potential anticancer agent. We hope that 62E2 described here is useful in expanding the diversity of cyanine fluorescent mitochondrial dyes and the analysis of their structure-activity relationships.
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http://dx.doi.org/10.1002/ardp.202000281DOI Listing
March 2021

Beilunmycin, a new virginiamycins antibiotic from mangrove-derived sp. 2BBP-J2 and the antibacterial activity by inhibiting protein translation.

J Asian Nat Prod Res 2020 Sep 14:1-9. Epub 2020 Sep 14.

Department of Microbial Chemistry, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China.

One new virginiamycin derivative, 'beilunmycin' (), and three known virginiamycin antibiotics, 16-hydroxy-virginiamycin M1 (), virginiamycin M2 (), and virginiamycin M1 (), were isolated from the culture of a mangrove-derived endophytic sp. 2BBP-J2. The structures were characterized on the basis of their spectroscopic data, and the absolute configuration of was established by ECD calculations. Compounds - exhibited antibacterial activities against Gram-positive bacteria, with MIC values in the range of 0.5-16 μg/ml. All the compounds demonstrated strong protein translation-stalling activity, with minimal concentrations detected with pDualrep2 in the range of 1.9-5.9 nmol.
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http://dx.doi.org/10.1080/10286020.2020.1810669DOI Listing
September 2020

Panel of potential lncRNA biomarkers can distinguish various types of liver malignant and benign tumors.

J Cancer Res Clin Oncol 2021 Jan 12;147(1):49-59. Epub 2020 Sep 12.

Center of Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo, Moscow, Russia, 143026.

Purpose: Liver cancers are among the deadliest malignancies due to a limited efficacy of early diagnostics, the lack of appropriate biomarkers and insufficient discrimination of different types of tumors by classic and molecular methods. In this study, we searched for novel long non-coding RNA (lncRNA) as well as validated several known candidates suitable as probable biomarkers for primary liver tumors of various etiology.

Methods: We described a novel lncRNA HELIS (aka "HEalthy LIver Specific") and estimated its expression by RT-qPCR in 82 paired tissue samples from patients with hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), combined HCC-CCA, pediatric hepatoblastoma (HBL) and non-malignant hepatocellular adenoma (HCA) and focal nodular hyperplasia (FNH). Additionally, we examined expression of cancer-associated lncRNAs HULC, MALAT1, UCA1, CYTOR, LINC01093 and H19, which were previously studied mainly in HCC.

Results: We demonstrated that down-regulation of HELIS strongly correlates with carcinogenesis; whereas in tumors with non-hepatocyte origin (HBL, CCA) or in a number of poorly differentiated HCC, this lncRNA is not expressed. We showed that recently discovered LINC01093 is dramatically down-regulated in all malignant liver cancers; while in benign tumors LINC01093 expression is just twice decreased in comparison to adjacent samples.

Conclusion: Our study revealed that among all measured biomarkers only down-regulated HELIS and LINC01093, up-regulated CYTOR and dysregulated HULC are perspective for differential diagnostics of liver cancers; whereas others demonstrated discordant results and cannot be considered as potential universal biomarkers for this purpose.
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http://dx.doi.org/10.1007/s00432-020-03378-5DOI Listing
January 2021

Insights into the structure and function of Est3 from the Hansenula polymorpha telomerase.

Sci Rep 2020 07 6;10(1):11109. Epub 2020 Jul 6.

M.V. Lomonosov Moscow State University, Moscow, 119991, Russia.

Telomerase is a ribonucleoprotein enzyme, which maintains genome integrity in eukaryotes and ensures continuous cellular proliferation. Telomerase holoenzyme from the thermotolerant yeast Hansenula polymorpha, in addition to the catalytic subunit (TERT) and telomerase RNA (TER), contains accessory proteins Est1 and Est3, which are essential for in vivo telomerase function. Here we report the high-resolution structure of Est3 from Hansenula polymorpha (HpEst3) in solution, as well as the characterization of its functional relationships with other components of telomerase. The overall structure of HpEst3 is similar to that of Est3 from Saccharomyces cerevisiae and human TPP1. We have shown that telomerase activity in H. polymorpha relies on both Est3 and Est1 proteins in a functionally symmetrical manner. The absence of either Est3 or Est1 prevents formation of a stable ribonucleoprotein complex, weakens binding of a second protein to TER, and decreases the amount of cellular TERT, presumably due to the destabilization of telomerase RNP. NMR probing has shown no direct in vitro interactions of free Est3 either with the N-terminal domain of TERT or with DNA or RNA fragments mimicking the probable telomerase environment. Our findings corroborate the idea that telomerase possesses the evolutionarily variable functionality within the conservative structural context.
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http://dx.doi.org/10.1038/s41598-020-68107-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7338525PMC
July 2020

Tetracenomycin X inhibits translation by binding within the ribosomal exit tunnel.

Nat Chem Biol 2020 10 29;16(10):1071-1077. Epub 2020 Jun 29.

Center of Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo, Russia.

The increase in multi-drug resistant pathogenic bacteria is making our current arsenal of clinically used antibiotics obsolete, highlighting the urgent need for new lead compounds with distinct target binding sites to avoid cross-resistance. Here we report that the aromatic polyketide antibiotic tetracenomycin (TcmX) is a potent inhibitor of protein synthesis, and does not induce DNA damage as previously thought. Despite the structural similarity to the well-known translation inhibitor tetracycline, we show that TcmX does not interact with the small ribosomal subunit, but rather binds to the large subunit, within the polypeptide exit tunnel. This previously unappreciated binding site is located adjacent to the macrolide-binding site, where TcmX stacks on the noncanonical basepair formed by U1782 and U2586 of the 23S ribosomal RNA. Although the binding site is distinct from the macrolide antibiotics, our results indicate that like macrolides, TcmX allows translation of short oligopeptides before further translation is blocked.
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http://dx.doi.org/10.1038/s41589-020-0578-xDOI Listing
October 2020

Translation at first sight: the influence of leading codons.

Nucleic Acids Res 2020 07;48(12):6931-6942

Skolkovo Institute of Science and Technology, Skolkovo, Moscow region 143025, Russia.

First triplets of mRNA coding region affect the yield of translation. We have applied the flowseq method to analyze >30 000 variants of the codons 2-11 of the fluorescent protein reporter to identify factors affecting the protein synthesis. While the negative influence of mRNA secondary structure on translation has been confirmed, a positive role of rare codons at the beginning of a coding sequence for gene expression has not been observed. The identity of triplets proximal to the start codon contributes more to the protein yield then more distant ones. Additional in-frame start codons enhance translation, while Shine-Dalgarno-like motifs downstream the initiation codon are inhibitory. The metabolic cost of amino acids affects the yield of protein in the poor medium. The most efficient translation was observed for variants with features resembling those of native Escherichia coli genes.
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http://dx.doi.org/10.1093/nar/gkaa430DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7337518PMC
July 2020

Synthesis and Evaluation of New Trivalent Ligands for Hepatocyte Targeting via the Asialoglycoprotein Receptor.

Bioconjug Chem 2020 05 9;31(5):1313-1319. Epub 2020 May 9.

Chemistry Department, Lomonosov Moscow State University, Moscow, 119991, Russian Federation.

Since the asialoglycoprotein receptor (also known as the "Ashwell-Morell receptor" or ASGPR) was discovered as the first cellular mammalian lectin, numerous drug delivery systems have been developed and several gene delivery systems associated with multivalent ligands for liver disease targeting are undergoing clinical trials. The success of these systems has facilitated the further study of new ligands with comparable or higher affinity and less synthetic complexity. Herein, we designed two novel trivalent ligands based on the esterification of tris(hydroxymethyl) aminomethane (TRIS) followed by the azide-alkyne Huisgen cycloaddition with azido -acetyl-d-galactosamine. The presented triazolyl glycoconjugates exhibited good binding to ASGPR, which was predicted using molecular docking and assessed by a surface plasmon resonance (SPR) technique. Moreover, we demonstrated the low level of cytotoxicity, as well as the optimal spatial geometry and the required amphiphilic balance, for new, easily accessible ligands. The conjugate of a new ligand with Cy5 dye exhibited selective penetration into HepG2 cells in contrast to the ASGPR-negative PC3 cell line.
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http://dx.doi.org/10.1021/acs.bioconjchem.0c00202DOI Listing
May 2020

Williams-Beuren syndrome-related methyltransferase WBSCR27: cofactor binding and cleavage.

FEBS J 2020 Dec 20;287(24):5375-5393. Epub 2020 Apr 20.

M.V. Lomonosov Moscow State University, Russia.

Williams-Beuren syndrome, characterized by numerous physiological and mental problems, is caused by the heterozygous deletion of chromosome region 7q11.23, which results in the disappearance of 26 protein-coding genes. Protein WBSCR27 is a product of one of these genes whose biological function has not yet been established and for which structural information has been absent until now. Using NMR, we investigated the structural and functional properties of murine WBSCR27. For protein in the apo form and in a complex with S-(5'-adenosyl)-l-homocysteine (SAH), a complete NMR resonance assignment has been obtained and the secondary structure has been determined. This information allows us to attribute WBSCR27 to Class I methyltransferases. The interaction of WBSCR27 with the cofactor S-(5'-adenosyl)-l-methionine (SAM) and its metabolic products - SAH, 5'-deoxy-5'-methylthioadenosine (MTA) and 5'-deoxyadenosine (5'dAdo) - was studied by NMR and isothermal titration calorimetry. SAH binds WBSCR27 much tighter than SAM, leaving open the question of cofactor turnover in the methylation reaction. One possible answer to this question is the presence of weak but detectable nucleosidase activity for WBSCR27. We found that the enzyme catalyses the cleavage of the adenine moiety from SAH, MTA and 5'dAdo, similar to the action of bacterial SAH/MTA nucleosidases. We also found that the binding of SAM or SAH causes a significant change in the structure of WBSCR27 and in the conformational mobility of the protein fragments, which can be attributed to the substrate recognition site. This indicates that the binding of the cofactor modulates the folding of the substrate-recognizing region of the enzyme.
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http://dx.doi.org/10.1111/febs.15320DOI Listing
December 2020

Influence of the spacer region between the Shine-Dalgarno box and the start codon for fine-tuning of the translation efficiency in Escherichia coli.

Microb Biotechnol 2020 07 23;13(4):1254-1261. Epub 2020 Mar 23.

Skolkovo Institute of Science and Technology, Moscow, 143025, Russia.

Translation efficiency contributes several orders of magnitude difference in the overall yield of exogenous gene expression in bacteria. In diverse bacteria, the translation initiation site, whose sequence is the primary determinant of the translation performance, is comprised of the start codon and the Shine-Dalgarno box located upstream. Here, we have examined how the sequence of a spacer between these main components of the translation initiation site contributes to the yield of synthesized protein. We have created a library of reporter constructs with the randomized spacer region, performed fluorescently activated cell sorting and applied next-generation sequencing analysis (the FlowSeq protocol). As a result, we have identified sequence motifs for the spacer region between the Shine-Dalgarno box and AUG start codon that may modulate the translation efficiency in a 100-fold range.
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http://dx.doi.org/10.1111/1751-7915.13561DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7264876PMC
July 2020

Comprehensive Functional Analysis of Ribosomal RNA Methyltransferases.

Front Genet 2020 27;11:97. Epub 2020 Feb 27.

Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.

Ribosomal RNAs in all organisms are methylated. The functional role of the majority of modified nucleotides is unknown. We systematically questioned the influence of rRNA methylation in on a number of characteristics of bacterial cells with the help of a set of rRNA methyltransferase (MT) gene knockout strains from the Keio collection. Analysis of ribosomal subunits sedimentation profiles of the knockout strains revealed a surprisingly small number of rRNA MT that significantly affected ribosome assembly. Accumulation of the assembly intermediates was observed only for the knockout strain whose growth was retarded most significantly among other rRNA MT knockout strains. Accumulation of the 17S rRNA precursor was observed for () knockout cells as well as for cells devoid of functional and genes. Significant differences were found among the WT and the majority of rRNA MT knockout strains in their ability to sustain exogenous protein overexpression. While the majority of the rRNA MT knockout strains supported suboptimal reporter gene expression, the strain devoid of the gene demonstrated a moderate increase in the yield of ectopic gene expression. Comparative 2D protein gel analysis of rRNA MT knockout strains revealed only minor perturbations of the proteome.
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http://dx.doi.org/10.3389/fgene.2020.00097DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7056703PMC
February 2020

Insights into the improved macrolide inhibitory activity from the high-resolution cryo-EM structure of dirithromycin bound to the 70S ribosome.

RNA 2020 06 6;26(6):715-723. Epub 2020 Mar 6.

Petersburg Nuclear Physics Institute named by B.P. Konstantinov of NRC "Kurchatov Institute," Gatchina, 188300, Russia.

Macrolides are one of the most successful and widely used classes of antibacterials, which kill or stop the growth of pathogenic bacteria by binding near the active site of the ribosome and interfering with protein synthesis. Dirithromycin is a derivative of the prototype macrolide erythromycin with additional hydrophobic side chain. In our recent study, we have discovered that the side chain of dirithromycin forms lone pair-π stacking interaction with the aromatic imidazole ring of the His69 residue in ribosomal protein uL4 of the 70S ribosome. In the current work, we found that neither the presence of the side chain, nor the additional contact with the ribosome, improve the binding affinity of dirithromycin to the ribosome. Nevertheless, we found that dirithromycin is a more potent inhibitor of in vitro protein synthesis in comparison with its parent compound, erythromycin. Using high-resolution cryo-electron microscopy, we determined the structure of the dirithromycin bound to the translating 70S ribosome, which suggests that the better inhibitory properties of the drug could be rationalized by the side chain of dirithromycin pointing into the lumen of the nascent peptide exit tunnel, where it can interfere with the normal passage of the growing polypeptide chain.
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http://dx.doi.org/10.1261/rna.073817.119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7266154PMC
June 2020

Exploitation of Potentially New Antibiotics from Mangrove Actinobacteria in Maowei Sea by Combination of Multiple Discovery Strategies.

Antibiotics (Basel) 2019 Nov 27;8(4). Epub 2019 Nov 27.

Department of Microbial Chemistry, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China.

Rediscovery of known antibiotics from actinobacteria, especially , has become a bottleneck issue. Nowadays, more specific identification and dereplication could be acquired by a combination of modern analytic techniques with various databases. In this study, 261 actinobacterial strains were isolated from 8 mangrove soil samples by culture-dependent method. A total of 83 strains were selected to evaluate antibacterial activities and mechanisms by disc diffusion method and a unique double fluorescent protein reporter system (pDualrep2), respectively. Thirty-two strains exhibited antagonistic activity against at least one of the "ESKAPE" pathogens. Four strains (B475, B486, B353, and B98) showed strong inhibitory activity against Gram-positive bacteria and induced DNA damage SOS response. One strain (B704) exhibited inhibitory activity against several pathogens and induced attenuation-based translational inhibitors reporter. Seven members of quinoxaline-type antibiotics including quinomycin A, quinomycin monosulfoxide, and other five putative new analogues were found from the culture broth of strain B475 by a combination of anti-MRSA guide, HPTLC, HPLC-UV, and UPLC-UV-HRESIMS/MS analysis, Chemspider searching, and MS/MS-based molecular networking analysis. In conclusion, this study not only demonstrated that mangrove is a rich source of actinobacteria with the potentially new antibiotics but showed rapid dereplication of known antibiotics in the early stage can improve efficiency for the discovery of new antibiotics.
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http://dx.doi.org/10.3390/antibiotics8040236DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6963217PMC
November 2019

Substituted Furanocoumarins as Novel Class of Antibacterial Translation Inhibitors.

Comb Chem High Throughput Screen 2019 ;22(6):400-410

Lomonosov Moscow State University, Chemistry Dept, Leninskie Gory, Building 1/3, GSP-1, Moscow 119991, Russian Federation.

Introduction: A variety of organic compounds has been reported to have antibacterial activity. However, antimicrobial resistance is one of the main problems of current anti-infective therapy, and the development of novel antibacterials is one of the main challenges of current drug discovery.

Methods: Using our previously developed dual-reporter High-Throughput Screening (HTS) platform, we identified a series of furanocoumarins as having high antibacterial activity. The construction of the reporter system allows us to differentiate three mechanisms of action for the active compounds: inhibition of protein synthesis (induction of Katushka2S), DNA damaging (induction of RFP) or other (inhibition of bacterial growth without reporter induction).

Results: Two primary hit-molecules of furanocoumarin series demonstrated relatively low MIC values comparable to that observed for Erythromycin (Ery) against E. coli and weakly induced both reporters. Dose-dependent translation inhibition was shown using in vitro luciferase assay, however it was not confirmed using C14-test. A series of close structure analogs of the identified hits was obtained and investigated using the same screening platform. Compound 19 was found to have slightly lower MIC value (15.18 µM) and higher induction of Katushka2S reporter in contrast to the parent structures. Moreover, translation blockage was clearly identified using both in vitro luciferase assay and C14 test. The standard cytotoxicity test revealed a relatively low cytotoxicity of the most active molecules.

Conclusion: High antibacterial activity in combination with low cytotoxicity was demonstrated for a series of furanocoumarins. Further optimization of the described structures may result in novel and attractive lead compounds with promising antibacterial efficiency.
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http://dx.doi.org/10.2174/1386207322666190723110539DOI Listing
August 2020

Identification of Novel Antibacterials Using Machine Learning Techniques.

Front Pharmacol 2019 27;10:913. Epub 2019 Aug 27.

Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia.

Many pharmaceutical companies are avoiding the development of novel antibacterials due to a range of rational reasons and the high risk of failure. However, there is an urgent need for novel antibiotics especially against resistant bacterial strains. Available models suffer from many drawbacks and, therefore, are not applicable for scoring novel molecules with high structural diversity by their antibacterial potency. Considering this, the overall aim of this study was to develop an efficient model able to find compounds that have plenty of chances to exhibit antibacterial activity. Based on a proprietary screening campaign, we have accumulated a representative dataset of more than 140,000 molecules with antibacterial activity against assessed in the same assay and under the same conditions. This intriguing set has no analogue in the scientific literature. We applied six techniques to mine these data. For external validation, we used 5,000 compounds with low similarity towards training samples. The antibacterial activity of the selected molecules against was assessed using a comprehensive biological study. Kohonen-based nonlinear mapping was used for the first time and provided the best predictive power (av. 75.5%). Several compounds showed an outstanding antibacterial potency and were identified as translation machinery inhibitors and . For the best compounds, MIC and CC values were determined to allow us to estimate a selectivity index (SI). Many active compounds have a robust IP position.
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http://dx.doi.org/10.3389/fphar.2019.00913DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6719509PMC
August 2019

2-Pyrazol-1-yl-thiazole derivatives as novel highly potent antibacterials.

J Antibiot (Tokyo) 2019 11 29;72(11):827-833. Epub 2019 Jul 29.

Lomonosov Moscow State University, Chemistry Department, Leninskie Gory, Building 1/3, GSP-1, 119991, Moscow, Russia.

The present report describes our efforts to identify new structural classes of compounds having promising antibacterial activity using previously published double-reporter system pDualrep2. This semi-automated high-throughput screening (HTS) platform has been applied to perform a large-scale screen of a diverse small-molecule compound library. We have selected a set of more than 125,000 molecules and evaluated them for their antibacterial activity. On the basis of HTS results, eight compounds containing 2-pyrazol-1-yl-thiazole scaffold exhibited moderate-to-high activity against ΔTolC Escherichia coli. Minimum inhibitory concentration (MIC) values for these molecules were in the range of 0.037-8 μg ml. The most active compound 8 demonstrated high antibacterial potency (MIC = 0.037 μg ml), that significantly exceed that measured for erythromycin (MIC = 2.5 μg ml) and was comparable with the activity of levofloxacin (MIC = 0.016 μg ml). Unfortunately, this compound showed only moderate selectivity toward HEK293 eukaryotic cell line. On the contrary, compound 7 was less potent (MIC = 0.8 μg ml) but displayed only slight cytotoxicity. Thus, 2-pyrazol-1-yl-thiazoles can be considered as a valuable starting point for subsequent optimization and morphing.
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http://dx.doi.org/10.1038/s41429-019-0211-yDOI Listing
November 2019

Studies on Antibacterial Activity and Diversity of Cultivable Actinobacteria Isolated from Mangrove Soil in Futian and Maoweihai of China.

Evid Based Complement Alternat Med 2019 9;2019:3476567. Epub 2019 Jun 9.

Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China.

Mangrove is a rich and underexploited ecosystem with great microbial diversity for discovery of novel and chemically diverse antimicrobial compounds. The goal of the study was to explore the pharmaceutical actinobacterial resources from mangrove soil and gain insight into the diversity and novelty of cultivable actinobacteria. Consequently, 10 mangrove soil samples were collected from Futian and Maoweihai of China, and the culture-dependent method was employed to obtain actinobacteria. A total of 539 cultivable actinobacteria were isolated and distributed in 39 genera affiliated to 18 families of 8 orders by comparison analysis of partial 16S rRNA gene sequences. The dominant genus was (16.0 %), followed by (14.5 %), (14.3 %), and (11.9 %). Other 35 rare actinobacterial genera accounted for minor proportions. Notably, 11 strains showed relatively low 16S rRNA gene sequence similarities (< 98.65 %) with validly described species. Based on genotypic analyses and phenotypic characteristics, 115 out of the 539 actinobacterial strains were chosen as representative strains to test their antibacterial activities against "ESKAPE" bacteria by agar well diffusion method and antibacterial mechanism by the double fluorescent protein reporter system. Fifty-four strains in 23 genera, including 2 potential new species, displayed antagonistic activity in antibacterial assay. Meanwhile, 5 strains in 3 genera exhibited inhibitory activity on protein biosynthesis due to ribosome stalling. These results demonstrate that cultivable actinobacteria from mangrove soil are potentially rich sources for discovery of new antibacterial metabolites and new actinobacterial taxa.
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http://dx.doi.org/10.1155/2019/3476567DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6590530PMC
June 2019

Large-scale High-throughput Screening Revealed 5'-(carbonylamino)-2,3'- bithiophene-4'-carboxylate as Novel Template for Antibacterial Agents.

Curr Drug Discov Technol 2020 ;17(5):716-724

Lomonosov Moscow State University, Chemistry Dept, Leninskie gory, Building 1/3, GSP-1, Moscow, 119991, Russian Federation.

Background: The key issue in the development of novel antimicrobials is a rapid expansion of new bacterial strains resistant to current antibiotics. Indeed, World Health Organization has reported that bacteria commonly causing infections in hospitals and in the community, e.g. E. Coli, K. pneumoniae and S. aureus, have high resistance vs the last generations of cephalosporins, carbapenems and fluoroquinolones. During the past decades, only few successful efforts to develop and launch new antibacterial medications have been performed. This study aims to identify new class of antibacterial agents using novel high-throughput screening technique.

Methods: We have designed library containing 125K compounds not similar in structure (Tanimoto coeff.< 0.7) to that published previously as antibiotics. The HTS platform based on double reporter system pDualrep2 was used to distinguish between molecules able to block translational machinery or induce SOS-response in a model E. coli system. MICs for most active chemicals in LB and M9 medium were determined using broth microdilution assay.

Results: In an attempt to discover novel classes of antibacterials, we performed HTS of a large-scale small molecule library using our unique screening platform. This approach permitted us to quickly and robustly evaluate a lot of compounds as well as to determine the mechanism of action in the case of compounds being either translational machinery inhibitors or DNA-damaging agents/replication blockers. HTS has resulted in several new structural classes of molecules exhibiting an attractive antibacterial activity. Herein, we report as promising antibacterials. Two most active compounds from this series showed MIC value of 1.2 (5) and 1.8 μg/mL (6) and good selectivity index. Compound 6 caused RFP induction and low SOS response. In vitro luciferase assay has revealed that it is able to slightly inhibit protein biosynthesis. Compound 5 was tested on several archival strains and exhibited slight activity against gram-negative bacteria and outstanding activity against S. aureus. The key structural requirements for antibacterial potency were also explored. We found, that the unsubstituted carboxylic group is crucial for antibacterial activity as well as the presence of bulky hydrophobic substituents at phenyl fragment.

Conclusion: The obtained results provide a solid background for further characterization of the 5'- (carbonylamino)-2,3'-bithiophene-4'-carboxylate derivatives discussed herein as new class of antibacterials and their optimization campaign.
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http://dx.doi.org/10.2174/1570163816666190603095521DOI Listing
January 2020

Functional duplication of Rap1 in methylotrophic yeasts.

Sci Rep 2019 05 10;9(1):7196. Epub 2019 May 10.

Faculty of Chemistry and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.

The telomere regulator and transcription factor Rap1 is the only telomere protein conserved in yeasts and mammals. Its functional repertoire in budding yeasts is a particularly interesting field for investigation, given the high evolutionary diversity of this group of unicellular organisms. In the methylotrophic thermotolerant species Hansenula polymorpha DL-1 the RAP1 gene is duplicated (HpRAP1A and HpRAP1B). Here, we report the functional characterization of the two paralogues from H. polymorpha DL-1. We uncover distinct (but overlapping) DNA binding preferences of HpRap1A and HpRap1B proteins. We show that only HpRap1B is able to recognize telomeric DNA directly and to protect it from excessive recombination, whereas HpRap1A is associated with subtelomere regions. Furthermore, we identify specific binding sites for both HpRap1A and HpRap1B within promoters of a large number of ribosomal protein genes (RPGs), implicating Rap1 in the control of the RP regulon in H. polymorpha. Our bioinformatic analysis suggests that RAP1 was duplicated early in the evolution of the "methylotrophs" clade, and the two genes evolved independently. Therefore, our characterization of Rap1 paralogues in H. polymorpha may be relevant to other "methylotrophs", yielding valuable insights into the evolution of budding yeasts.
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http://dx.doi.org/10.1038/s41598-019-43595-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6510891PMC
May 2019

Identification of N-Substituted Triazolo-azetidines as Novel Antibacterials using pDualrep2 HTS Platform.

Comb Chem High Throughput Screen 2019 08;22(5):346-354

Lomonosov Moscow State University, Chemistry Dept, Leninskie gory, Building 1/3, GSP-1, Moscow, 119991, Russian Federation.

Aim And Objective: Antibiotic resistance is a serious constraint to the development of new effective antibacterials. Therefore, the discovery of the new antibacterials remains one of the main challenges in modern medicinal chemistry. This study was undertaken to identify novel molecules with antibacterial activity.

Materials And Methods: Using our unique double-reporter system, in-house large-scale HTS campaign was conducted for the identification of antibacterial potency of small-molecule compounds. The construction allows us to visually assess the underlying mechanism of action. After the initial HTS and rescreen procedure, luciferase assay, C14-test, determination of MIC value and PrestoBlue test were carried out.

Results: HTS rounds and rescreen campaign have revealed the antibacterial activity of a series of Nsubstituted triazolo-azetidines and their isosteric derivatives that has not been reported previously. Primary hit-molecule demonstrated a MIC value of 12.5 µg/mL against E. coli Δ tolC with signs of translation blockage and no SOS-response. Translation inhibition (26%, luciferase assay) was achieved at high concentrations up to 160 µg/mL, while no activity was found using C14-test. The compound did not demonstrate cytotoxicity in the PrestoBlue assay against a panel of eukaryotic cells. Within a series of direct structural analogues bearing the same or bioisosteric scaffold, compound 2 was found to have an improved antibacterial potency (MIC=6.25 µg/mL) close to Erythromycin (MIC=2.5-5 µg/mL) against the same strain. In contrast to the parent hit, this compound was more active and selective, and provided a robust IP position.

Conclusion: N-substituted triazolo-azetidine scaffold may be used as a versatile starting point for the development of novel active and selective antibacterial compounds.
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http://dx.doi.org/10.2174/1386207322666190412165316DOI Listing
August 2019

Identification of pyrrolo-pyridine derivatives as novel class of antibacterials.

Mol Divers 2020 Feb 4;24(1):233-239. Epub 2019 Apr 4.

Chemistry Department, Lomonosov Moscow State University, Leninskie Gory, Building 1/3 GSP-1, Moscow, Russian Federation, 119991.

A series of 5-oxo-4H-pyrrolo[3,2-b]pyridine derivatives was identified as novel class of highly potent antibacterial agents during an extensive large-scale high-throughput screening (HTS) program utilizing a unique double-reporter system-pDualrep2. The construction of the reporter system allows us to perform visual inspection of the underlying mechanism of action due to two genes-Katushka2S and RFP-which encode the proteins with different imaging signatures. Antibacterial activity of the compounds was evaluated during the initial HTS round and subsequent rescreen procedure. The most active molecule demonstrated a MIC value of 3.35 µg/mL against E. coli with some signs of translation blockage (low Katushka2S signal) and no SOS response. The compound did not demonstrate cytotoxicity in standard cell viability assay. Subsequent structural morphing and follow-up synthesis may result in novel compounds with a meaningful antibacterial potency which can be reasonably regarded as an attractive starting point for further in vivo investigation and optimization.
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http://dx.doi.org/10.1007/s11030-019-09946-3DOI Listing
February 2020

Structure of Dirithromycin Bound to the Bacterial Ribosome Suggests New Ways for Rational Improvement of Macrolides.

Antimicrob Agents Chemother 2019 06 24;63(6). Epub 2019 May 24.

Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA

Although macrolides are known as excellent antibacterials, their medical use has been significantly limited due to the spread of bacterial drug resistance. Therefore, it is necessary to develop new potent macrolides to combat the emergence of drug-resistant pathogens. One of the key steps in rational drug design is the identification of chemical groups that mediate binding of the drug to its target and their subsequent derivatization to strengthen drug-target interactions. In the case of macrolides, a few groups are known to be important for drug binding to the ribosome, such as desosamine. Search for new chemical moieties that improve the interactions of a macrolide with the 70S ribosome might be of crucial importance for the invention of new macrolides. For this purpose, here we studied a classic macrolide, dirithromycin, which has an extended (2-methoxyethoxy)-methyl side chain attached to the C-9/C-11 atoms of the macrolactone ring that can account for strong binding of dirithromycin to the 70S ribosome. By solving the crystal structure of the 70S ribosome in complex with dirithromycin, we found that its side chain interacts with the wall of the nascent peptide exit tunnel in an idiosyncratic fashion: its side chain forms a lone pair-π stacking interaction with the aromatic imidazole ring of the His69 residue in ribosomal protein uL4. To our knowledge, the ability of this side chain to form a contact in the macrolide binding pocket has not been reported previously and potentially can open new avenues for further exploration by medicinal chemists developing next-generation macrolide antibiotics active against resistant pathogens.
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http://dx.doi.org/10.1128/AAC.02266-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6535518PMC
June 2019

NMR assignments of the WBSCR27 protein related to Williams-Beuren syndrome.

Biomol NMR Assign 2018 10 4;12(2):303-308. Epub 2018 Jun 4.

Faculty of Fundamental Medicine, Center for Magnetic Tomography and Spectroscopy, M.V. Lomonosov Moscow State University, Moscow, Russia, 119991.

Williams-Beuren syndrome is a genetic disorder characterized by physiological and mental abnormalities, and is caused by hemizygous deletion of several genes in chromosome 7. One of the removed genes encodes the WBSCR27 protein. Bioinformatic analysis of the sequence of WBSCR27 indicates that it belongs to the family of SAM-dependent methyltransferases. However, exact cellular functions of this protein or phenotypic consequences of its deficiency are still unknown. Here we report nearly complete H, N, and C chemical shifts assignments of the 26 kDa WBSCR27 protein from Mus musculus in complex with the cofactor S-adenosyl-L-methionine (SAM). Analysis of the assigned chemical shifts allowed us to characterize the protein's secondary structure and backbone dynamics. The topology of the protein's fold confirms the assumption that the WBSCR27 protein belongs to the family of class I methyltransferases.
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http://dx.doi.org/10.1007/s12104-018-9827-2DOI Listing
October 2018

Diversity, Novelty, and Antimicrobial Activity of Endophytic Actinobacteria From Mangrove Plants in Beilun Estuary National Nature Reserve of Guangxi, China.

Front Microbiol 2018 4;9:868. Epub 2018 May 4.

Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.

Endophytic actinobacteria are one of the important pharmaceutical resources and well known for producing different types of bioactive substances. Nevertheless, detection of the novelty, diversity, and bioactivity on endophytic actinobacteria isolated from mangrove plants are scarce. In this study, five different mangrove plants, , and , were collected from Beilun Estuary National Nature Reserve in Guangxi Zhuang Autonomous Region, China. A total of 101 endophytic actinobacteria strains were recovered by culture-based approaches. They distributed in 7 orders, 15 families, and 28 genera including , and . Among them, seven strains were potentially new species of genera , and . Above all, strain 8BXZ-J1 has already been characterized as a new species of the genus . A total of 63 out of 101 strains were chosen to screen antibacterial activities by paper-disk diffusion method and inhibitors of ribosome and DNA biosynthesis by means of a double fluorescent protein reporter. A total of 31 strains exhibited positive results in at least one antibacterial assay. Notably, strain 8BXZ-J1 and three other potential novel species, 7BMP-1, 5BQP-J3, and 1BXZ-J1, all showed antibacterial bioactivity. In addition, 21 strains showed inhibitory activities against at least one "ESKAPE" resistant pathogens. We also found that strains 2BBP-J2 and 1BBP-1 produce bioactive compound with inhibitory activity on protein biosynthesis as result of translation stalling. Meanwhile, strain 3BQP-1 produces bioactive compound inducing SOS-response due to DNA damage. In conclusion, this study proved mangrove plants harbored a high diversity of cultivable endophytic actinobacteria, which can be a promising source for discovery of novel species and bioactive compounds.
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http://dx.doi.org/10.3389/fmicb.2018.00868DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5945994PMC
May 2018

Structural and evolutionary insights into ribosomal RNA methylation.

Nat Chem Biol 2018 02;14(3):226-235

Skolkovo Institute of Science and Technology, Skolkovo, Moscow Region, Russia.

Methylation of nucleotides in ribosomal RNAs (rRNAs) is a ubiquitous feature that occurs in all living organisms. Identification of all enzymes responsible for rRNA methylation, as well as mapping of all modified rRNA residues, is now complete for a number of model species, such as Escherichia coli and Saccharomyces cerevisiae. Recent high-resolution structures of bacterial ribosomes provided the first direct visualization of methylated nucleotides. The structures of ribosomes from various organisms and organelles have also lately become available, enabling comparative structure-based analysis of rRNA methylation sites in various taxonomic groups. In addition to the conserved core of modified residues in ribosomes from the majority of studied organisms, structural analysis points to the functional roles of some of the rRNA methylations, which are discussed in this Review in an evolutionary context.
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http://dx.doi.org/10.1038/nchembio.2569DOI Listing
February 2018