Publications by authors named "Emilia Maria Pedone"

16 Publications

  • Page 1 of 1

Structural Insight of the Full-Length Ros Protein: A Prototype of the Prokaryotic Zinc-Finger Family.

Sci Rep 2020 06 9;10(1):9283. Epub 2020 Jun 9.

Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "Luigi Vanvitelli", via Vivaldi, 43, 81100, Caserta, Italy.

Ros/MucR is a widespread family of bacterial zinc-finger (ZF) containing proteins that integrate multiple functions such as virulence, symbiosis and/or cell cycle transcription. NMR solution structure of Ros DNA-binding domain (region 56-142, i.e. Ros87) has been solved by our group and shows that the prokaryotic ZF domain shows interesting structural and functional features that differentiate it from its eukaryotic counterpart as it folds in a significantly larger zinc-binding globular domain. We have recently proposed a novel functional model for this family of proteins suggesting that they may act as H-NS-'like' gene silencers. Indeed, the N-terminal region of this family of proteins appears to be responsible for the formation of functional oligomers. No structural characterization of the Ros N-terminal domain (region 1-55) is available to date, mainly because of serious solubility problems of the full-length protein. Here we report the first structural characterization of the N-terminal domain of the prokaryotic ZF family examining by means of MD and NMR the structural preferences of the full-length Ros protein from Agrobacterium tumefaciens.
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http://dx.doi.org/10.1038/s41598-020-66204-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7283297PMC
June 2020

Cystatin B Involvement in Synapse Physiology of Rodent Brains and Human Cerebral Organoids.

Front Mol Neurosci 2019 16;12:195. Epub 2019 Aug 16.

Department of Biology, University of Naples Federico II, Naples, Italy.

Cystatin B (CSTB) is a ubiquitous protein belonging to a superfamily of protease inhibitors. CSTB may play a critical role in brain physiology because its mutations cause progressive myoclonic epilepsy-1A (EPM1A), the most common form of progressive myoclonic epilepsy. However, the molecular mechanisms underlying the role of CSTB in the central nervous system (CNS) are largely unknown. To investigate the possible involvement of CSTB in the synaptic plasticity, we analyzed its expression in synaptosomes as a model system in studying the physiology of the synaptic regions of the CNS. We found that CSTB is not only present in the synaptosomes isolated from rat and mouse brain cortex, but also secreted into the medium in a depolarization-controlled manner. In addition, using biorthogonal noncanonical amino acid tagging (BONCAT) procedure, we demonstrated, for the first time, that CSTB is locally synthesized in the synaptosomes. The synaptic localization of CSTB was confirmed in a human 3D model of cortical development, namely cerebral organoids. Altogether, these results suggest that CSTB may play a role in the brain plasticity and open a new perspective in studying the involvement of CSTB deregulation in neurodegenerative and neuropsychiatric diseases.
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http://dx.doi.org/10.3389/fnmol.2019.00195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6707391PMC
August 2019

Molecular basis of the scalp-ear-nipple syndrome unraveled by the characterization of disease-causing KCTD1 mutants.

Sci Rep 2019 07 19;9(1):10519. Epub 2019 Jul 19.

Institute of Biostructures and Bioimaging, CNR, Via Mezzocannone 16, 80134, Napoli, Italy.

The scalp-ear-nipple (SEN) syndrome is an autosomal-dominant disorder characterized by cutis aplasia of the scalp and malformations of breast, external ears, digits, and nails. Genetic analyses have shown that the disease is caused by missense mutations of the KCTD1 protein, although the functional/structural basis of SEN insurgence is hitherto unknown. With the aim of unravelling the molecular basis of the SEN syndrome associated with KCTD1 mutations we here expressed and characterized several disease causing mutants. A preliminary dissection of the protein provides insights into the role that individual domains play in KCTD1 stability. The characterization of SEN-causing mutants indicates that, although the mutation sites are located in distant regions of the BTB domain or of the pre-BTB region, all of them are unable to interact with the transcription factor AP-2α, a well-known KCTD1 biological partner. Notably, all mutations, including the one located in the pre-BTB region, produce a significant destabilization of the protein. The structural role of the pre-BTB region in KCTD1 and other proteins of the family is corroborated by its sequence conservation in orthologs and paralogs. Interestingly, SEN-causing mutations also favor the tendency of KCTD1 to adopt structural states that are characterized by the ability to bind the β-amyloid fluorescent dye thioflavin T. The formation of aggregation-prone species may have important implications for the disease etiology. Collectively, these findings provide an intriguing picture of the functional and structural alterations induced by KCTD1 mutations that ultimately lead to disease.
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http://dx.doi.org/10.1038/s41598-019-46911-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6642198PMC
July 2019

Design and analysis of EphA2-SAM peptide ligands: A multi-disciplinary screening approach.

Bioorg Chem 2019 03 8;84:434-443. Epub 2018 Dec 8.

Institute of Biostructures and Bioimaging (CNR), Naples, Italy; InterUniversity Research Centre on Bioactive Peptides (CIRPEB), University of Naples Federico II, Naples, Italy. Electronic address:

EphA2 receptor plays a critical and debatable function in cancer and is considered a target in drug discovery. Lately, there has been a growing interest in its cytosolic C-terminal SAM domain (EphA2-SAM) as it engages protein modulators of receptor endocytosis and stability. Interestingly, EphA2-SAM binds the SAM domain from the lipid phosphatase Ship2 (Ship2-SAM) mainly producing pro-oncogenic outcomes. In an attempt to discover novel inhibitors of the EphA2-SAM/Ship2-SAM complex with possible anticancer properties, we focused on the central region of Ship2-SAM (known as Mid-Loop interface) responsible for its binding to EphA2-SAM. Starting from the amino acid sequence of the Mid-Loop interface virtual peptide libraries were built through ad hoc inserted mutations with either l- or d- amino acids and screened against EphA2-SAM by docking techniques. A few virtual hits were synthesized and experimentally tested by a variety of direct and competition-type interaction assays relying on NMR (Nuclear Magnetic Resonance), SPR (Surface Plasmon Resonance), MST (Microscale Thermophoresis) techniques. These studies guided the discovery of an original EphA2-SAM ligand antagonist of its interaction with Ship2-SAM.
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http://dx.doi.org/10.1016/j.bioorg.2018.12.009DOI Listing
March 2019

Identifying the region responsible for Brucella abortus MucR higher-order oligomer formation and examining its role in gene regulation.

Sci Rep 2018 11 22;8(1):17238. Epub 2018 Nov 22.

Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "Luigi Vanvitelli", Caserta, 81100, Italy.

MucR is a member of the Ros/MucR family of prokaryotic zinc-finger proteins found in the α-proteobacteria which regulate the expression of genes required for the successful pathogenic and symbiotic interactions of these bacteria with the eukaryotic hosts. The structure and function of their distinctive zinc-finger domain has been well-studied, but only recently the quaternary structure of the full length proteins was investigated demonstrating their ability to form higher-order oligomers. The aim of this study was to identify the region of MucR involved in higher-order oligomer formation by analysing deletion and point mutants of this protein by Light Scattering, and to determine the role that MucR oligomerization plays in the regulatory function of this protein. Here we demonstrate that a conserved hydrophobic region at the N-terminus of MucR is responsible for higher-order oligomer formation and that MucR oligomerization is essential for its regulatory function in Brucella. All these features of MucR are shared by the histone-like nucleoid structuring protein, (H-NS), leading us to propose that the prokaryotic zinc-finger proteins in the MucR/Ros family control gene expression employing a mechanism similar to that used by the H-NS proteins, rather than working as classical transcriptional regulators.
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http://dx.doi.org/10.1038/s41598-018-35432-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6250670PMC
November 2018

Sam domain-based stapled peptides: Structural analysis and interaction studies with the Sam domains from the EphA2 receptor and the lipid phosphatase Ship2.

Bioorg Chem 2018 10 20;80:602-610. Epub 2018 Jul 20.

Institute of Biostructures and Bioimaging (CNR), Naples, Italy; InterUniversity Research Centre on Bioactive Peptides (CIRPEB), University of Naples Federico II, Naples, Italy. Electronic address:

Sam (Sterile alpha motif) domains represent small helical protein-protein interaction modules which play versatile functions in different cellular processes. The Sam domain from the EphA2 receptor binds the Sam domain of the lipid phosphatase Ship2 and this interaction modulates receptor endocytosis and degradation primarily generating pro-oncogenic effects in cell. To identify molecule antagonists of the EphA2-Sam/Ship2-Sam complex with anti-cancer activity, we focused on hydrocarbon helical stapled peptides. EphA2-Sam and one of its interactors (i.e., the first Sam domain of the adaptor protein Odin) were used as model systems for peptide design. Increase in helicity in the stapled peptides, with respect to the corresponding linear/native-like regions, was proved by structural studies conducted through CD (Circular Dichroism) and NMR (Nuclear Magnetic Resonance). Interestingly, interaction assays by means of NMR, SPR (Surface Plasmon Resonance) and MST (MicroScale Thermophoresis) techniques led to the discovery of a novel ligand of Ship2-Sam.
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http://dx.doi.org/10.1016/j.bioorg.2018.07.013DOI Listing
October 2018

Folding mechanisms steer the amyloid fibril formation propensity of highly homologous proteins.

Chem Sci 2018 Apr 1;9(13):3290-3298. Epub 2018 Mar 1.

Department of Environmental, Biological and Pharmaceutical Sciences and Technologies , University of Campania "Luigi Vanvitelli" , Via Vivaldi 43 , 81100 Caserta , Italy . Email:

Significant advances in the understanding of the molecular determinants of fibrillogenesis can be expected from comparative studies of the aggregation propensities of proteins with highly homologous structures but different folding pathways. Here, we fully characterize, by means of stopped-flow, T-jump, CD and DSC experiments, the unfolding mechanisms of three highly homologous proteins, zinc binding Ros87 and Ml1 and zinc-lacking Ml4. The results indicate that the three proteins significantly differ in terms of stability and (un)folding mechanisms. Particularly, Ros87 and Ml1 appear to be much more stable to guanidine denaturation and are characterized by folding mechanisms including the presence of an intermediate. On the other hand, metal lacking Ml4 folds according to a classic two-state model. Successively, we have monitored the capabilities of Ros87, Ml4 and Ml1 to form amyloid fibrils under native conditions. Particularly, we show, by CD, fluorescence, DLS, TEM and SEM experiments, that after 168 hours, amyloid formation of Ros87 has started, while Ml1 has formed only amorphous aggregates and Ml4 is still monomeric in solution. This study shows how metal binding can influence protein folding pathways and thereby control conformational accessibility to aggregation-prone states, which in turn changes aggregation kinetics, shedding light on the role of metal ions in the development of protein deposition diseases.
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http://dx.doi.org/10.1039/c8sc00166aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5933289PMC
April 2018

MucR binds multiple target sites in the promoter of its own gene and is a heat-stable protein: Is MucR a H-NS-like protein?

FEBS Open Bio 2018 04 31;8(4):711-718. Epub 2018 Mar 31.

Department of Environmental, Biological and Pharmaceutical Sciences and Technologies University of Campania 'Luigi Vanvitelli' Caserta Italy.

The protein MucR from spp. is involved in the expression regulation of genes necessary for host interaction and infection. MucR is a member of the Ros/MucR family, which comprises prokaryotic zinc-finger proteins and includes Ros from and the Ml proteins from . MucR from spp. can regulate the expression of virulence genes and repress its own gene expression. Despite the well-known role played by MucR in the repression of its own gene, no target sequence has yet been identified in the promoter gene. In this study, we provide the first evidence that MucR from binds more than one target site in the promoter region of its own gene, suggesting a molecular mechanism by which this protein represses its own expression. Furthermore, a circular dichroism analysis reveals that MucR is a heat-stable protein. Overall, the results of this study suggest that MucR might resemble a H-NS protein.
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http://dx.doi.org/10.1002/2211-5463.12411DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5881533PMC
April 2018

The Sam-Sam interaction between Ship2 and the EphA2 receptor: design and analysis of peptide inhibitors.

Sci Rep 2017 12 12;7(1):17474. Epub 2017 Dec 12.

Institute of Biostructures and Bioimaging (IBB), CNR, via Mezzocannone 16, 80134, Naples, Italy.

The lipid phosphatase Ship2 represents a drug discovery target for the treatment of different diseases, including cancer. Its C-terminal sterile alpha motif domain (Ship2-Sam) associates with the Sam domain from the EphA2 receptor (EphA2-Sam). This interaction is expected to mainly induce pro-oncogenic effects in cells therefore, inhibition of the Ship2-Sam/EphA2-Sam complex may represent an innovative route to discover anti-cancer therapeutics. In the present work, we designed and analyzed several peptide sequences encompassing the interaction interface of EphA2-Sam for Ship2-Sam. Peptide conformational analyses and interaction assays with Ship2-Sam conducted through diverse techniques (CD, NMR, SPR and MST), identified a positively charged penta-amino acid native motif in EphA2-Sam, that once repeated three times in tandem, binds Ship2-Sam. NMR experiments show that the peptide targets the negatively charged binding site of Ship2-Sam for EphA2-Sam. Preliminary in vitro cell-based assays indicate that -at 50 µM concentration- it induces necrosis of PC-3 prostate cancer cells with more cytotoxic effect on cancer cells than on normal dermal fibroblasts. This work represents a pioneering study that opens further opportunities for the development of inhibitors of the Ship2-Sam/EphA2-Sam complex for therapeutic applications.
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http://dx.doi.org/10.1038/s41598-017-17684-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5727260PMC
December 2017

Ml proteins from Mesorhizobium loti and MucR from Brucella abortus: an AT-rich core DNA-target site and oligomerization ability.

Sci Rep 2017 Nov 17;7(1):15805. Epub 2017 Nov 17.

Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "Luigi Vanvitelli", Caserta, 81100, Italy.

Mesorhizobium loti contains ten genes coding for proteins sharing high amino acid sequence identity with members of the Ros/MucR transcription factor family. Five of these Ros/MucR family members from Mesorhizobium loti (Ml proteins) have been recently structurally and functionally characterized demonstrating that Ml proteins are DNA-binding proteins. However, the DNA-binding studies were performed using the Ros DNA-binding site with the Ml proteins. Currently, there is no evidence as to when the Ml proteins are expressed during the Mesorhizobium lo ti life cycle as well as no information concerning their natural DNA-binding site. In this study, we examine the ml genes expression profile in Mesorhizobium loti and show that ml1, ml2, ml3 and ml5 are expressed during planktonic growth and in biofilms. DNA-binding experiments show that the Ml proteins studied bind a conserved AT-rich site in the promoter region of the exoY gene from Mesorhizobium loti and that the proteins make important contacts with the minor groove of DNA. Moreover, we demonstrate that the Ml proteins studied form higher-order oligomers through their N-terminal region and that the same AT-rich site is recognized by MucR from Brucella abortus using a similar mechanism involving contacts with the minor groove of DNA and oligomerization.
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http://dx.doi.org/10.1038/s41598-017-16127-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5693944PMC
November 2017

Proteins involved in sleep homeostasis: Biophysical characterization of INC and its partners.

Biochimie 2016 Dec 24;131:106-114. Epub 2016 Sep 24.

Institute of Biostructures and Bioimaging, C.N.R., Via Mezzocannone 16, 80134 Napoli, Italy. Electronic address:

The insomniac protein of Drosophila melanogaster (INC) has a crucial role in sleep homeostasis as flies lacking the inc gene exhibit strikingly reduced and poorly consolidated sleep. Nevertheless, in vitro characterizations of INC biophysical properties and partnerships have not been yet reported. Here we report the heterologous expression of the protein and its characterization using a number of different techniques. Present data indicate that INC is endowed with a remarkable stability, which results from the cooperation of the two protein domains. Moreover, we also demonstrated and quantified the ability of INC to recognize its potential partners Cul3 and dGRASP. Taking into account the molecular organization of the protein, these two partners may be anchored simultaneously. Although there is no evident relationship between the reported INC functions and dGRASP binding, our data suggest that INC may cooperate as ligase adaptor to dGRASP ubiquitination. SAXS data collected on the complex between INC and Cul3, which represent the first structural characterization of this type of assemblies, clearly highlight the highly dynamic nature of these complexes. This strongly suggests that the functional behavior of these proteins cannot be understood if dynamic effects are not considered. Finally, the strict analogy of the biochemical/biophysical properties of INC and of its human homolog KCTD5 may reliably indicate that this latter protein and/or the closely related proteins KCTD2/KCTD17 may play important roles in human sleep regulation.
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http://dx.doi.org/10.1016/j.biochi.2016.09.013DOI Listing
December 2016

Cullin 3 Recognition Is Not a Universal Property among KCTD Proteins.

PLoS One 2015 14;10(5):e0126808. Epub 2015 May 14.

Institute of Biostructures and Bioimaging, C.N.R., 80134, Napoli, Italy.

Cullin 3 (Cul3) recognition by BTB domains is a key process in protein ubiquitination. Among Cul3 binders, a great attention is currently devoted to KCTD proteins, which are implicated in fundamental biological processes. On the basis of the high similarity of BTB domains of these proteins, it has been suggested that the ability to bind Cul3 could be a general property among all KCTDs. In order to gain new insights into KCTD functionality, we here evaluated and/or quantified the binding of Cul3 to the BTB of KCTD proteins, which are known to be involved either in cullin-independent (KCTD12 and KCTD15) or in cullin-mediated (KCTD6 and KCTD11) activities. Our data indicate that KCTD6(BTB) and KCTD11(BTB) bind Cul3 with high affinity forming stable complexes with 4:4 stoichiometries. Conversely, KCTD12(BTB) and KCTD15(BTB) do not interact with Cul3, despite the high level of sequence identity with the BTB domains of cullin binding KCTDs. Intriguingly, comparative sequence analyses indicate that the capability of KCTD proteins to recognize Cul3 has been lost more than once in distinct events along the evolution. Present findings also provide interesting clues on the structural determinants of Cul3-KCTD recognition. Indeed, the characterization of a chimeric variant of KCTD11 demonstrates that the swapping of α2β3 loop between KCTD11(BTB) and KCTD12(BTB) is sufficient to abolish the ability of KCTD11(BTB) to bind Cul3. Finally, present findings, along with previous literature data, provide a virtually complete coverage of Cul3 binding ability of the members of the entire KCTD family.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0126808PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4431850PMC
February 2016

Molecular recognition of Cullin3 by KCTDs: insights from experimental and computational investigations.

Biochim Biophys Acta 2014 Jul 18;1844(7):1289-98. Epub 2014 Apr 18.

Institute of Biostructures and Bioimaging, C.N.R., 80134 Napoli, Italy. Electronic address:

Recent investigations have highlighted a key role of the proteins of the KCTD (K-potassium channel tetramerization domain containing proteins) family in several fundamental biological processes. Despite the growing importance of KCTDs, our current understanding of their biophysical and structural properties is very limited. Biochemical characterizations of these proteins have shown that most of them act as substrate adaptor in E3 ligases during protein ubiquitination. Here we present a characterization of the KCTD5-Cullin3 interactions which are mediated by the KCTD5 BTB domain. Isothermal titration calorimetry experiments reveal that KCTD5 avidly binds the Cullin3 (Cul3). The complex presents a 5:5 stoichiometry and a dissociation constant of 59 nM. Molecular modeling and molecular dynamics simulations clearly indicate that the two proteins form a stable (KCTD5-Cul3)(5) pinwheel-shaped heterodecamer in which two distinct KCTD5 subunits cooperate in the binding of each cullin chain. Molecular dynamics simulations indicate that different types of interactions contribute to the stability of the assembly. Interestingly, residues involved in Cul3 recognitions are conserved in the KCTD5 orthologs and paralogs implicated in important biological processes. These residues are also rather well preserved in most of the other KCTD proteins. By using molecular modeling techniques, the entire ubiquitination system including the E3 ligase, the E2 conjugating enzyme and ubiquitin was generated. The analysis of the molecular architecture of this complex machinery provides insights into the ubiquitination processes which involve E3 ligases with a high structural complexity.
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http://dx.doi.org/10.1016/j.bbapap.2014.04.006DOI Listing
July 2014

Solution structure of the first Sam domain of Odin and binding studies with the EphA2 receptor.

Biochemistry 2012 Mar 5;51(10):2136-45. Epub 2012 Mar 5.

Department of Biological Sciences, University of Naples Federico II, Naples, Italy.

The EphA2 receptor plays key roles in many physiological and pathological events, including cancer. The process of receptor endocytosis and the consequent degradation have attracted attention as possible means of overcoming the negative outcomes of EphA2 in cancer cells and decreasing tumor malignancy. A recent study indicates that Sam (sterile alpha motif) domains of Odin, a member of the ANKS (ankyrin repeat and sterile alpha motif domain-containing) family of proteins, are important for the regulation of EphA2 endocytosis. Odin contains two tandem Sam domains (Odin-Sam1 and -Sam2). Herein, we report on the nuclear magnetic resonance (NMR) solution structure of Odin-Sam1; through a variety of assays (employing NMR, surface plasmon resonance, and isothermal titration calorimetry techniques), we clearly demonstrate that Odin-Sam1 binds to the Sam domain of EphA2 in the low micromolar range. NMR chemical shift perturbation experiments and molecular modeling studies point out that the two Sam domains interact with a head-to-tail topology characteristic of several Sam-Sam complexes. This binding mode is similar to that we have previously proposed for the association between the Sam domains of the lipid phosphatase Ship2 and EphA2. This work further validates structural elements relevant for the heterotypic Sam-Sam interactions of EphA2 and provides novel insights for the design of potential therapeutic compounds that can modulate receptor endocytosis.
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http://dx.doi.org/10.1021/bi300141hDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3319784PMC
March 2012

Molecular organization of the cullin E3 ligase adaptor KCTD11.

Biochimie 2011 Apr 13;93(4):715-24. Epub 2011 Jan 13.

Institute of Biostructures and Bioimaging, CNR, Napoli, Italy.

The family of human proteins containing a potassium channel tetramerization domain (KCTD) includes 21 members whose function is largely unknown. Recent reports have however suggested that these proteins are implicated in very important biological processes. KCTD11/REN, the best-characterized member of the family to date, plays a crucial role in the ubiquitination of HDAC1 by acting, in complex with Cullin3, as an E3 ubiquitin ligase. By combining bioinformatics and mutagenesis analyses, here we show that the protein is expressed in two alternative variants: a short previously characterized form (sKCTD11) composed by 232 amino acids and a longer variant (lKCTD11) which contains an N-terminal extension of 39 residues. Interestingly, we demonstrate that lKCTD11 starts with a non-canonical AUU codon. Although both sKCTD11 and lKCTD11 bear a POZ/BTB domain in their N-terminal region, this domain is complete only in the long form. Indeed, sKCTD11 presents an incomplete POZ/BTB domain. Nonetheless, sKCTD11 is still able to bind Cul3, although to much lesser extent than lKCTD11, and to perform its biological activity. The heterologous expression of sKCTD11 and lKCTD11 and their individual domains in Escherichia coli yielded soluble products as fusion proteins only for the longer form. In contrast to the closely related KCTD5 which is pentameric, the characterization of both lKCTD11 and its POZ/BTB domain by gel filtration and light scattering indicates that the protein likely forms stable tetramers. In line with this result, experiments conducted in cells show that the active protein is not monomeric. Based on these findings, homology-based models were built for lKCTD11 BTB and for its complex with Cul3. These analyses indicate that a stable lKCTD11 BTB-Cul3 three-dimensional model with a 4:4 stoichiometry can be generated. Moreover, these models provide insights into the determinants of the tetramer stability and into the regions involved in lKCTD11-Cul3 recognition.
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http://dx.doi.org/10.1016/j.biochi.2010.12.014DOI Listing
April 2011

Histone deacetylase and Cullin3-REN(KCTD11) ubiquitin ligase interplay regulates Hedgehog signalling through Gli acetylation.

Nat Cell Biol 2010 Feb 17;12(2):132-42. Epub 2010 Jan 17.

Department of Experimental Medicine, Sapienza University, 324 viale Regina Elena, 00161 Rome, Italy.

Hedgehog signalling is crucial for development and is deregulated in several tumours, including medulloblastoma. Regulation of the transcriptional activity of Gli (glioma-associated oncogene) proteins, effectors of the Hedgehog pathway, is poorly understood. We show here that Gli1 and Gli2 are acetylated proteins and that their HDAC-mediated deacetylation promotes transcriptional activation and sustains a positive autoregulatory loop through Hedgehog-induced upregulation of HDAC1. This mechanism is turned off by HDAC1 degradation through an E3 ubiquitin ligase complex formed by Cullin3 and REN, a Gli antagonist lost in human medulloblastoma. Whereas high HDAC1 and low REN expression in neural progenitors and medulloblastomas correlates with active Hedgehog signalling, loss of HDAC activity suppresses Hedgehog-dependent growth of neural progenitors and tumour cells. Consistent with this, abrogation of Gli1 acetylation enhances cellular proliferation and transformation. These data identify an integrated HDAC- and ubiquitin-mediated circuitry, where acetylation of Gli proteins functions as an unexpected key transcriptional checkpoint of Hedgehog signalling.
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http://dx.doi.org/10.1038/ncb2013DOI Listing
February 2010
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