Publications by authors named "Zeinab Takalloo"

12 Publications

  • Page 1 of 1

Thermophilic iron containing type superoxide dismutase from Cohnella sp. A01.

Int J Biol Macromol 2021 Sep 27;187:373-385. Epub 2021 Jul 27.

Bioprocess Engineering Group, Institute of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran. Electronic address:

Superoxide dismutases (SODs) (EC 1.15.1.1) are well known antioxidant enzymes that play critical roles in cellular defenses of living organisms against harmful superoxide radicals during oxidative stress. This study details on cloning, biochemical and functional characterization of an iron containing type superoxide dismutase (SOD) from a novel thermophilic bacteria Cohnella sp. A01 (CaSOD). The secondary and three dimensional structure of the protein were predicted. CaSOD gene was subsequently cloned into pET-26b(+) expression vector and expression of the recombinant protein (rCaSOD) was optimized in E. coli BL21 (DE3) and the purified recombinant SOD showed a single band with an apparent molecular weight of 26 kDa by SDS-PAGE. The half-life and thermodynamic parameters including ΔH, ΔS, and ΔG were 187 min at 60 °C, 7.3 kJ.mol, -76.8 kJ.mol.°K, and 84.1 kJ.mol, respectively. The rCaSOD exhibited catalytic activity in a very broad range of pH (6.0-10.0) and temperatures (35-75 °C), as well as stability in a broad pH range, from 3.0 to 11.0, and wide range of temperature, different concentrations of detergent agents, metal ions, organic solvents and other chemicals. The results suggest that this novel enzyme could be used for various industrial applications in cosmetic, food, and pharmaceutical industries.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijbiomac.2021.07.150DOI Listing
September 2021

The trypsin inhibitor pro-peptide induces toxic effects in Indianmeal moth, Plodia interpunctella.

Pestic Biochem Physiol 2021 Jan 15;171:104730. Epub 2020 Oct 15.

Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran. Electronic address:

The inhibitory potential of an inhibitor peptide based on the pro-region of trypsin zymogen was investigated in Indianmeal moth, P. interpunctella, which is a world-wide insect pest of stored food. Five peptides were designed based on molecular docking simulations. The designed peptide with the best score was selected and synthesized for further screening in vitro and in vivo. The peptide was characterized and its inhibitory effects towards the insect trypsin were evaluated and the kinetic analysis revealed a competitive type of inhibition against the target enzyme. The results showed that the peptide could successfully suppress the pest midgut trypsin, and more interestingly, it did not show considerable inhibitory effects on a mammalian trypsin. We also aimed to assess the effect of dietary insect meal treated with different concentrations of the peptide and observed a significant growth and development retardation in pupa and adult insects fed with the inhibitor peptide. The outcomes of the present study suggest an efficient inhibitor peptide that could specifically bind the P. interpunctella trypsin and inhibit its activity, which would be safe against human being health and environment. Notably, this is the first report on in vivo assessment of the direct effect of a pro-region as the specific inhibitor in development as well as survival of the pest insect. Furthermore, our findings could be a promising for future designed pesticides used in pest management.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.pestbp.2020.104730DOI Listing
January 2021

Stress-dependent conformational changes of artemin: Effects of heat and oxidant.

PLoS One 2020 16;15(11):e0242206. Epub 2020 Nov 16.

Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.

Artemin is an abundant thermostable protein in Artemia embryos and it is considered as a highly efficient molecular chaperone against extreme environmental stress conditions. The conformational dynamics of artemin have been suggested to play a critical role in its biological functions. In this study, we have investigated the conformational and functional changes of artemin under heat and oxidative stresses to identify the relationship between its structure and function. The tertiary and quaternary structures of artemin were evaluated by fluorescence measurements, protein cross-linking analysis, and dynamic light scattering. Based on the structural analysis, artemin showed irreversible substantial conformational lability in responses to heat and oxidant, which was mainly mediated through the hydrophobic interactions and dimerization of the chaperone. In addition, the chaperone-like activity of heated and oxidized artemin was examined using lysozyme refolding assay and the results showed that although both factors, i.e. heat and oxidant, at specific levels improved artemin potency, simultaneous incubation with both stressors significantly triggered the chaperone activation. Moreover, the heat-induced dimerization of artemin was found to be the most critical factor for its activation. It was suggested that oxidation presumably acts through stabilizing the dimer structures of artemin through formation of disulfide bridges between the subunits and strengthens its chaperoning efficacy. Accordingly, it is proposed that artemin probably exists in a monomer-oligomer equilibrium in Artemia cysts and environmental stresses and intracellular portion of protein substrates may shift the equilibrium towards the active dimer forms of the chaperone.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0242206PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7668597PMC
January 2021

Probing heat and oxidation induced conformational changes of molecular chaperone artemin by excitation-emission fluorescence spectroscopy.

J Photochem Photobiol B 2020 Oct 3;211:112013. Epub 2020 Sep 3.

Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran. Electronic address:

Artemin is a potent molecular chaperone, which protects Artemia embryos undergoing encystment against extreme environmental stresses. In the present work, we have examined the structural changes of artemin from A. urmiana upon exposure to oxidant and heat, by using CD measurements as well as excitation-emission fluorescence spectroscopy as a powerful tool for monitoring the conformational transitions and molecular interactions in proteins. We have also provided here the first document on reporting the three dimensional fluorescence spectra of a protein using ANS. Totally, the fluorescence results indicated that the microenvironments of tyrosine and tryptophan residues and the hydrophobic pockets as well as the polypeptide backbone or secondary structure of the chaperone were influenced in responses to heat and HO in different degrees. Moreover, the native state of artemin did not induce a considerable exposure of the internal non-polar groups to the solvent. Besides, the excitation-emission spectra of heated artemin by ANS revealed new emission peaks at 430-450 nm when it was excited at 330 nm, which suggests probable exposure of new binding sites for hydrophobic or electrostatic interactions of the protein with ANS. The protein also showed a greater conformational sensitivity to the temperature fluctuations compared to oxidation. Here, we presented some evidence in support of the relation between artemin and its stress dependent activation in vitro and in vivo. This study can expect that the EEM fluorescence spectroscopy could provide a promising tool to study conformational transitions of proteins.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jphotobiol.2020.112013DOI Listing
October 2020

Interplay of isoform 1N4R tau protein and amyloid-β peptide fragment 25-35 in reducing and non-reducing conditions.

J Biochem 2021 Feb;169(1):119-134

Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Jalal AleAhmad Highway, P.O.Box: 14115-111, Iran.

Amyloid-β (Aβ) peptide and tau protein are two hallmark proteins in Alzheimer's disease (AD); however, the parameters, which mediate the abnormal aggregation of Aβ and tau, have not been fully discovered. Here, we have provided an optimum method to purify tau protein isoform 1N4R by using nickel-nitrilotriacetic acid agarose chromatography under denaturing condition. The biochemical and biophysical properties of the purified protein were further characterized using in vitro tau filament assembly, tubulin polymerization assay, circular dichroism (CD) spectroscopy and atomic force microscopy. Afterwards, we investigated the effect of tau protein on aggregation of Aβ (25-35) peptide using microscopic imaging and cell viability assay. Incubation of tau at physiologic and supra-physiologic concentrations with Aβ25-35 for 40 days under reducing and non-reducing conditions revealed formation of two types of aggregates with distinct morphologies and dimensions. In non-reducing condition, the co-incubated sample showed granular aggregates, while in reducing condition, they formed annular protofibrils. Results from cell viability assay revealed the increased cell viability for the co-incubated sample. Therefore, the disassembling action shown by tau protein on Aβ25-35 suggests the possibility that tau may have a protective role in preventing Aβ peptide from acquiring the cytotoxic, aggregated form against oxidative stress damages.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/jb/mvaa101DOI Listing
February 2021

Autolysis, plasmolysis and enzymatic hydrolysis of baker's yeast (Saccharomyces cerevisiae): a comparative study.

World J Microbiol Biotechnol 2020 Apr 24;36(5):68. Epub 2020 Apr 24.

Kimiazyme Company, Modares Science & Technology Park, Tarbiat Modares University, Tehran, Iran.

Saccharomyces cerevisiae is being used for long as a rich source of proteins, sugars, nucleotides, vitamins and minerals. Autolyzed and hydrolyzed yeast biomass has found numerous applications in the health food industry as well as livestock feeds. Here, we have compared three lysis methods for production of yeast lysates using autolysis, plasmolysis (ethyl acetate 1.5%), and enzymatic hydrolysis (Alcalase 0.2%). The efficiency of each process was compared according to soluble solid and protein contents, cell lysis monitoring, and release of intracellular materials, cell viability and microscopic analysis. Results showed that plasmolysis by ethyl acetate was found to be more efficient compared to autolysis, with a higher recovery of yeast extract (YE) content. In comparison, the content of released solids and proteins were higher during the enzymatic hydrolysis using Alcalase compared to autolysis and plasmolysis treatments. The highest decrease in optical density of 600 nm was monitored for the hydrolyzed cells. Besides, we defined "Degree of Leakage (DL)" as a new index of the lysis process, referring to the percentage of total released proteins from the cells and it was estimated to about 65.8%, which represents an appropriate indicator of the cell lysis. The biochemical and biophysical properties of the hydrolyzed yeast product as well as its biological activity (free radical scavenging activity and bacterial binding capacity) suggest that Alcalase could be used to accelerate the lysis of yeast cells and release the valuable intracellular components used for foodstuffs, feed and fermentation media applications. Production of baker's yeast lysates using autolysis, plasmolysis, and enzymatic hydrolysis methods.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11274-020-02840-3DOI Listing
April 2020

Modulation of the competition between renaturation and aggregation of lysozyme by additive mixtures.

Biotechnol Appl Biochem 2020 May 29;67(3):330-342. Epub 2019 Dec 29.

Department of Biochemistry, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.

The effects of 17 kinds of additive mixtures have been studied on refolding and aggregation of a model protein, lysozyme. Most of the prepared mixtures were efficient in inhibiting aggregation of the protein, and, surprisingly, four novel additive mixtures, i.e., lactic acid: l-arginine, lactic acid: l-glutamine, choline chloride: lactic acid, and imidazolium salt: β-cyclodextrin as well as choline chloride: urea exhibited a more remarkable efficacy in suppressing aggregation. Among these, lactic acid: l-arginine was identified as the most efficient additive, and lactic acid: l-glutamine and choline chloride: lactic acid were inefficient to recover the enzyme activity. In contrast, choline chloride: ethylene glycol: imidazole, choline chloride: glycerol: imidazole, imidazole: betaine: ethylene glycol were found to be less effective mixtures in preventing enzyme aggregation. Totally, it was demonstrated that the protective effects of the mixtures were improved as their concentrations increased. The improvement was more remarkable for imidazolium salt: β-cyclodextrin and choline chloride: urea, where the denatured lysozyme was reactivated and recovered up to 85% of its initial activity by enhancing their concentrations from 1 to 5% (V/V). It is suggested that such solution additives may be further employed as artificial chaperones to assist protein folding and stability.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/bab.1864DOI Listing
May 2020

afpCOOL: A tool for antifreeze protein prediction.

Heliyon 2018 Jul 25;4(7):e00705. Epub 2018 Jul 25.

Bioinformatics and Computational Omics Lab (BioCOOL), Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.

Various cold-adapted organisms produce antifreeze proteins (AFPs), which prevent the freezing of cell fluids by inhibiting the growth of ice crystals. AFPs are currently being recognized in various organisms, living in extremely low temperatures. AFPs have several important applications in increasing freeze tolerance of plants, maintaining the tissue in frozen conditions and producing cold-hardy plants by applying transgenic technology. Substantial differences in the sequence and structure of the AFPs, pose a challenge for researchers to identify these proteins. In this paper, we proposed a novel method to identify AFPs, using supportive vector machine (SVM) by incorporating 4 types of features. Results of the two used benchmark datasets, revealed the strength of the proposed method in AFP prediction. According to the results of an independent test setup, our method outperformed the current state-of-the-art methods. In addition, the comparison results of the discrimination power of different feature types revealed that physicochemical descriptors are the most contributing features in AFP detection. This method has been implemented as a stand-alone tool, named afpCOOL, for various operating systems to predict AFPs with a user friendly graphical interface.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.heliyon.2018.e00705DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6074609PMC
July 2018

Improving the soluble expression of aequorin in Escherichia coli using the chaperone-based approach by co-expression with artemin.

Prep Biochem Biotechnol 2018 29;48(6):483-489. Epub 2018 Jun 29.

a Department of Biochemistry, Faculty of Biological Sciences , Tarbiat Modares University , Tehran , Iran.

Escherichia coli is a common host that is widely used for producing recombinant proteins. However, it is a simple approach for production of heterologous proteins; the major drawbacks in using this organism include incorrect protein folding and formation of disordered aggregated proteins as inclusion bodies. Co-expression of target proteins with certain molecular chaperones is a rational approach for this problem. Aequorin is a calcium-activated photoprotein that is often prone to form insoluble inclusion bodies when overexpressed in E. coli cells resulting in low active yields. Therefore, in the present research, our main aim is to increase the soluble yield of aequorin as a model protein and minimize its inclusion body content in the bacterial cells. We have applied the chaperone-assisted protein folding strategy for enhancing the yield of properly folded protein with the assistance of artemin as an efficient molecular chaperone. The results here indicated that the content of the soluble form of aequorin was increased when it was co-expressed with artemin. Moreover, in the co-expressing cells, the bioluminescence activity was higher than the control sample. We presume that this method might be a potential tool to promote the solubility of other aggregation-prone proteins in bacterial cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1080/10826068.2018.1466152DOI Listing
January 2019

An inter-subunit disulfide bond of artemin acts as a redox switch for its chaperone-like activity.

Cell Stress Chaperones 2018 07 10;23(4):685-693. Epub 2018 Feb 10.

Department of Microbiology, Faculty of Basic Sciences, Lahijan Branch, Islamic Azad University (IAU), Lahijan, Guilan, Iran.

Encysted embryos of Artemia are among the most stress-resistant eukaryotes partly due to the massive amount of a cysteine-rich protein termed artemin. High number of cysteine residues in artemin and their intramolecular spatial positions motivated us to investigate the role of the cysteine residues in the chaperone-like activity of artemin. According to the result of Ellman's assay, there are nine free thiols (seven buried and two exposed) and one disulfide bond per monomer of artemin. Subsequent theoretical analysis of the predicted 3D structure of artemin confirmed the data obtained by the spectroscopic study. Native and reduced/modified forms of artemin were also compared with respect to their efficiency in chaperoning activity, tertiary structure, and stability. Since the alkylation and reduction of artemin diminished its chaperone activity, it appears that its chaperoning potential depends on the formation of intermolecular disulfide bond and the presence of cysteine residues. Comparative fluorescence studies on the structure and stability of the native and reduced protein revealed some differences between them. Due to the redox-dependent functional switching of artemin from the less to more active form, it can be finally suggested as a redox-dependent chaperone.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s12192-018-0880-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6045527PMC
July 2018

Artemin protects cells and proteins against oxidative and salt stress.

Int J Biol Macromol 2017 Feb 25;95:618-624. Epub 2016 Nov 25.

Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.

Artemin is an abundant thermostable protein in Artemia encysted embryos under environmental stresses. It is confirmed that high regulatory expression of artemin is relevant to stress resistance in this crustacean. Here, the protective role of artemin from Artemia urmiana has been investigated on survival of bacterial cells under salt and oxidative shocks. Also, for continuous monitoring of the effect of artemin in prevention of proteins aggregation/inactivation, co-expression of artemin and luciferase (as an intracellular reporter) in bacterial cells was performed. According to the results, residual activity of luciferase in artemin expressing E. coli cells exposing to different concentrations of HO and NaCl was significantly higher than non-expressing cells. The luciferase activity was rapidly lost in control cells under salt treatments while in co-transformed cells, the activity was considerably retained at higher salt concentrations. Also, analysis from cell viability assays showed that artemin-expressing cells exhibited more resistance to both stress conditions. In the present study, we document for the first time that artemin can protect proteins and bacterial cells against oxidative and salt stress conditions. These results can declare the resistance property of this crustacean against harsh environmental conditions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijbiomac.2016.11.088DOI Listing
February 2017

Real-time monitoring of artemin in vivo chaperone activity using luciferase as an intracellular reporter.

Arch Biochem Biophys 2016 Nov 28;610:33-40. Epub 2016 Sep 28.

Department of Biology, Faculty of Science, University of Guilan, Rasht, Iran.

Artemin is an abundant thermostable protein in Artemia encysted embryos and considered as a stress protein, as its highly regulated expression is associated with stress resistance. Artemin cDNA was previously isolated and cloned from Artemia urmiana and artemin was found as an efficient molecular chaperone in vitro. Here, co-transformation of E. coli was performed with two expression vectors containing artemin and firefly luciferase for in vivo studies. The time-course of luciferase inactivation at low and elevated temperatures showed that luciferase was rapidly inactivated in control cells, but it was found that luciferase was protected significantly in artemin expressing cells. More interestingly, luciferase activity was completely regained in heat treated artemin expressing cells at room temperature. In addition, in both stress conditions, similar to residual activity of luciferase, cell viability in induced cultures over-expressing artemin was significantly higher than non-expressed artemin cells. It can be suggested that artemin confers impressive resistance in stressful conditions when introduced into E. coli cells, which is due to that it protects proteins against aggregation. Such luciferase co-expression system can be used as a real-time reporter to investigate the activity of chaperone proteins in vivo and provide a rapid and simple test for molecular chaperones.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.abb.2016.09.016DOI Listing
November 2016
-->