scholarly journals Structural basis for the regulation of nucleosome recognition and HDAC activity by histone deacetylase assemblies

2021 ◽  
Vol 7 (2) ◽  
pp. eabd4413
Author(s):  
Jung-Hoon Lee ◽  
Daniel Bollschweiler ◽  
Tillman Schäfer ◽  
Robert Huber
Keyword(s):  
Transcriptional Repression ◽  
Histone Deacetylases ◽  
Active Sites ◽  
Chromatin Modification ◽  
Structural Basis ◽  
Amino Terminal ◽  
Cryo Electron Microscopy ◽  
Multiple Contacts ◽  
Lysine Residues ◽  
Nucleosome Binding

The chromatin-modifying histone deacetylases (HDACs) remove acetyl groups from acetyl-lysine residues in histone amino-terminal tails, thereby mediating transcriptional repression. Structural makeup and mechanisms by which multisubunit HDAC complexes recognize nucleosomes remain elusive. Our cryo–electron microscopy structures of the yeast class II HDAC ensembles show that the HDAC protomer comprises a triangle-shaped assembly of stoichiometry Hda12-Hda2-Hda3, in which the active sites of the Hda1 dimer are freely accessible. We also observe a tetramer of protomers, where the nucleosome binding modules are inaccessible. Structural analysis of the nucleosome-bound complexes indicates how positioning of Hda1 adjacent to histone H2B affords HDAC catalysis. Moreover, it reveals how an intricate network of multiple contacts between a dimer of protomers and the nucleosome creates a platform for expansion of the HDAC activities. Our study provides comprehensive insight into the structural plasticity of the HDAC complex and its functional mechanism of chromatin modification.

scholarly journals The DNA Binding and Catalytic Domains of Poly(ADP-Ribose) Polymerase 1 Cooperate in the Regulation of Chromatin Structure and Transcription

2007 ◽  
Vol 27 (21) ◽  
pp. 7475-7485 ◽  
Author(s):  
David A. Wacker ◽  
Donald D. Ruhl ◽  
Ehsan H. Balagamwala ◽  
Kristine M. Hope ◽  
Tong Zhang ◽  
...  
Keyword(s):  
Dna Binding ◽  
Enzymatic Activity ◽  
Chromatin Structure ◽  
Transcriptional Repression ◽  
Catalytic Domain ◽  
Vitro Assay ◽  
Chromatin Compaction ◽  
Amino Terminal ◽  
Nucleosome Binding ◽  
Parp 1

ABSTRACT We explored the mechanisms of chromatin compaction and transcriptional regulation by poly(ADP-ribose) polymerase 1 (PARP-1), a nucleosome-binding protein with an NAD+-dependent enzymatic activity. By using atomic force microscopy and a complementary set of biochemical assays with reconstituted chromatin, we showed that PARP-1 promotes the localized compaction of chromatin into supranucleosomal structures in a manner independent of the amino-terminal tails of core histones. In addition, we defined the domains of PARP-1 required for nucleosome binding, chromatin compaction, and transcriptional repression. Our results indicate that the DNA binding domain (DBD) of PARP-1 is necessary and sufficient for binding to nucleosomes, yet the DBD alone is unable to promote chromatin compaction and only partially represses RNA polymerase II-dependent transcription in an in vitro assay with chromatin templates (∼50% of the repression observed with wild-type PARP-1). Furthermore, our results show that the catalytic domain of PARP-1, which does not bind nucleosomes on its own, cooperates with the DBD to promote chromatin compaction and efficient transcriptional repression in a manner independent of its enzymatic activity. Collectively, our results have revealed a novel function for the catalytic domain in chromatin compaction. In addition, they show that the DBD and catalytic domain cooperate to regulate chromatin structure and chromatin-dependent transcription, providing mechanistic insights into how these domains contribute to the chromatin-dependent functions of PARP-1.

scholarly journals Structural basis of the regulation of the normal and oncogenic methylation of nucleosomal histone H3 Lys36 by NSD2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ko Sato ◽  
Amarjeet Kumar ◽  
Keisuke Hamada ◽  
Chikako Okada ◽  
Asako Oguni ◽  
...  
Keyword(s):  
Histone H3 ◽  
Structural Basis ◽  
Wild Type ◽  
Cryo Electron Microscopy ◽  
Nucleosomal Dna ◽  
Oncogenic Mutations ◽  
Binding Cleft ◽  
Dynamics Simulations ◽  
Nucleosome Binding ◽  
Nucleosomal Histone

AbstractDimethylated histone H3 Lys36 (H3K36me2) regulates gene expression, and aberrant H3K36me2 upregulation, resulting from either the overexpression or point mutation of the dimethyltransferase NSD2, is found in various cancers. Here we report the cryo-electron microscopy structure of NSD2 bound to the nucleosome. Nucleosomal DNA is partially unwrapped, facilitating NSD2 access to H3K36. NSD2 interacts with DNA and H2A along with H3. The NSD2 autoinhibitory loop changes its conformation upon nucleosome binding to accommodate H3 in its substrate-binding cleft. Kinetic analysis revealed that two oncogenic mutations, E1099K and T1150A, increase NSD2 catalytic turnover. Molecular dynamics simulations suggested that in both mutants, the autoinhibitory loop adopts an open state that can accommodate H3 more often than the wild-type. We propose that E1099K and T1150A destabilize the interactions that keep the autoinhibitory loop closed, thereby enhancing catalytic turnover. Our analyses guide the development of specific inhibitors of NSD2.

scholarly journals Cryo-EM structures of undocked innexin-6 hemichannels in phospholipids

2020 ◽  
Vol 6 (7) ◽  
pp. eaax3157 ◽  
Author(s):  
Batuujin Burendei ◽  
Ruriko Shinozaki ◽  
Masakatsu Watanabe ◽  
Tohru Terada ◽  
Kazutoshi Tani ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Structural Basis ◽  
Wild Type ◽  
Amino Terminal ◽  
Functional Assays ◽  
Cryo Electron Microscopy ◽  
Dynamics Simulations ◽  
Open States ◽  
Insight Into ◽  
Junction Proteins

Gap junctions form intercellular conduits with a large pore size whose closed and open states regulate communication between adjacent cells. The structural basis of the mechanism by which gap junctions close, however, remains uncertain. Here, we show the cryo–electron microscopy structures of Caenorhabditis elegans innexin-6 (INX-6) gap junction proteins in an undocked hemichannel form. In the nanodisc-reconstituted structure of the wild-type INX-6 hemichannel, flat double-layer densities obstruct the channel pore. Comparison of the hemichannel structures of a wild-type INX-6 in detergent and nanodisc-reconstituted amino-terminal deletion mutant reveals that lipid-mediated amino-terminal rearrangement and pore obstruction occur upon nanodisc reconstitution. Together with molecular dynamics simulations and electrophysiology functional assays, our results provide insight into the closure of the INX-6 hemichannel in a lipid bilayer before docking of two hemichannels.

scholarly journals Class II Histone Deacetylases Confer Signal Responsiveness to the Ankyrin-Repeat Proteins ANKRA2 and RFXANK

2006 ◽  
Vol 17 (1) ◽  
pp. 438-447 ◽  
Author(s):  
Timothy A. McKinsey ◽  
Koichiro Kuwahara ◽  
Svetlana Bezprozvannaya ◽  
Eric N. Olson
Keyword(s):  
Gene Expression ◽  
Transcriptional Repression ◽  
Nuclear Export ◽  
Histone Deacetylases ◽  
Class Ii ◽  
Ankyrin Repeat ◽  
Amino Terminal ◽  
Mhc Ii ◽  
Repeat Proteins ◽  
Ankyrin Repeat Proteins

Class II histone deacetylases (HDACs) contain unique amino-terminal extensions that mediate interactions with members of the myocyte enhancer factor-2 (MEF2) family of transcription factors and responsiveness to kinases, including Ca2+/calmodulin-dependent kinase (CaMK). Despite intense investigation of class II HDACs, little is known of MEF2-independent mechanisms for transcriptional repression by these chromatin-modifying enzymes. Here, we demonstrate that class II HDACs 4 and 5 physically associate with ankyrin-repeat proteins ANKRA2 and RFXANK (RFX-B/Tvl-1/ANKRA1). ANKRA2 is a megalin- and BKCa potassium channel-interacting factor, whereas RFXANK is a positive regulator of major histocompatibility complex II (MHC II) gene expression. HDAC4 and HDAC5 interact with the ankyrin repeats of ANKRA2 and RFXANK and, through association with RFXANK, repress MHC II promoter activation. HDACs 4 and 5 also repress endogenous HLA-DRA gene expression induced by CIITA. Phosphorylation of class II HDACs by CaMK results in CRM1-dependent nuclear export of HDAC/RFXANK complexes. These results define a novel transcriptional pathway under the control of class II HDACs and suggest a role for these transcriptional repressors as signal-responsive regulators of antigen presentation.

Transcriptional repression by Tup1–Ssn6This paper is one of a selection of papers published in this Special Issue, entitled 27th International West Coast Chromatin and Chromosome Conference, and has undergone the Journal's usual peer review process.

2006 ◽  
Vol 84 (4) ◽  
pp. 437-443 ◽  
Author(s):  
Tania M. Malavé ◽  
Sharon Y.R. Dent
Keyword(s):  
Dna Binding ◽  
West Coast ◽  
Transcriptional Repression ◽  
Histone Deacetylases ◽  
Review Process ◽  
Peer Review Process ◽  
Chromatin Modification ◽  
Special Issue ◽  
Higher Eukaryotes ◽  
Selection Of

The Tup1–Ssn6 complex from budding yeast is one of the best studied corepressors and has served as a model for the study of similar corepressor complexes in higher eukaryotes. Tup1–Ssn6 represses multiple subsets of genes when recruited to promoters by sequence-specific DNA binding repressors. Tup1–Ssn6 mediated repression involves interactions among the corepressor and hypoacetylated histones, histone deacetylases, and the RNA transcriptional machinery. Nucleosome positioning is also involved in repression of a subset of Tup1–Ssn6 regulated genes. These findings highlight the importance of chromatin modification states in Tup1–Ssn6 mediated repression. Here we review the multiple mechanisms involved in repression and discuss Tup1–Ssn6 homolog functions in higher organisms. We also present a model for how repression by Tup1–Ssn6 may be established.

scholarly journals SUMOylation of the Corepressor N-CoR Modulates Its Capacity to Repress Transcription

2006 ◽  
Vol 17 (4) ◽  
pp. 1643-1651 ◽  
Author(s):  
Jens Tiefenbach ◽  
Natalia Novac ◽  
Miryam Ducasse ◽  
Maresa Eck ◽  
Frauke Melchior ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Posttranslational Modifications ◽  
Transcriptional Repression ◽  
Histone Deacetylases ◽  
Hormone Receptors ◽  
Target Genes ◽  
Protein Protein Interactions ◽  
Lysine Residues

In the absence of ligands the corepressor N-CoR mediates transcriptional repression by some nuclear hormone receptors. Several protein–protein interactions of N-CoR are known, of which mainly complex formation with histone deacetylases (HDACs) leads to the repression of target genes. On the other hand, the role of posttranslational modifications in corepressor function is not well established. Here, we show that N-CoR is modified by Sumo-1. We found SUMO-E2–conjugating enzyme Ubc9 and SUMO-E3 ligase Pias1 as novel N-CoR interaction partners. The SANT1 domain of N-CoR was found to mediate this interaction. We show that K152, K1117, and K1330 of N-CoR can be conjugated to SUMO and that mutation of all sites is necessary to fully block SUMOylation in vitro. Because these lysine residues are located within repression domains I and III, respectively, we investigated a possible correlation between the functions of the repression domains and SUMOylation. Coexpression of Ubc9 protein resulted in enhanced N-CoR–dependent transcriptional repression. Studies using SUMOylation-deficient N-CoR RDI mutants suggest that SUMO modification contributes to repression by N-CoR. Mutation of K152 to R in RD1, for example, not only significantly reduced repression of a reporter gene, but also abolished the effect of Ubc9 on transcriptional repression.

scholarly journals Comprehensive Analysis of the Histone Deacetylase Gene Family in Chinese Cabbage (Brassica rapa): From Evolution and Expression Pattern to Functional Analysis of BraHDA3

Agriculture ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 244
Author(s):  
Seung Hee Eom ◽  
Tae Kyung Hyun
Keyword(s):  
Functional Analysis ◽  
Brassica Rapa ◽  
Chinese Cabbage ◽  
Stress Responses ◽  
Histone Deacetylases ◽  
Expression Patterns ◽  
Evolutionary Relationship ◽  
Gene Families ◽  
Physiological Processes ◽  
Lysine Residues

Histone deacetylases (HDACs) are known as erasers that remove acetyl groups from lysine residues in histones. Although plant HDACs play essential roles in physiological processes, including various stress responses, our knowledge concerning HDAC gene families and their evolutionary relationship remains limited. In Brassica rapa genome, we identified 20 HDAC genes, which are divided into three major groups: RPD3/HDA1, HD2, and SIR2 families. In addition, seven pairs of segmental duplicated paralogs and one pair of tandem duplicated paralogs were identified in the B. rapa HDAC (BraHDAC) family, indicating that segmental duplication is predominant for the expansion of the BraHDAC genes. The expression patterns of paralogous gene pairs suggest a divergence in the function of BraHDACs under various stress conditions. Furthermore, we suggested that BraHDA3 (homologous of Arabidopsis HDA14) encodes the functional HDAC enzyme, which can be inhibited by Class I/II HDAC inhibitor SAHA. As a first step toward understanding the epigenetic responses to environmental stresses in Chinese cabbage, our results provide a solid foundation for functional analysis of the BraHDAC family.

scholarly journals Involvement of loop 5 lysine residues and the N-terminal β-hairpin of the ribotoxin hirsutellin A on its insecticidal activity

2016 ◽  
Vol 397 (2) ◽  
pp. 135-145 ◽  
Author(s):  
Miriam Olombrada ◽  
Lucía García-Ortega ◽  
Javier Lacadena ◽  
Mercedes Oñaderra ◽  
José G. Gavilanes ◽  
...  
Keyword(s):  
Active Sites ◽  
Structural Changes ◽  
The Other ◽  
Spatial Proximity ◽  
Ribonucleolytic Activity ◽  
The Family ◽  
Lysine Residues ◽  
Hirsutella Thompsonii ◽  
Close Spatial Proximity ◽  
High Degree

Abstract Ribotoxins are cytotoxic members of the family of fungal extracellular ribonucleases best represented by RNase T1. They share a high degree of sequence identity and a common structural fold, including the geometric arrangement of their active sites. However, ribotoxins are larger, with a well-defined N-terminal β-hairpin, and display longer and positively charged unstructured loops. These structural differences account for their cytotoxic properties. Unexpectedly, the discovery of hirsutellin A (HtA), a ribotoxin produced by the invertebrate pathogen Hirsutella thompsonii, showed how it was possible to accommodate these features into a shorter amino acid sequence. Examination of HtA N-terminal β-hairpin reveals differences in terms of length, charge, and spatial distribution. Consequently, four different HtA mutants were prepared and characterized. One of them was the result of deleting this hairpin [Δ(8-15)] while the other three affected single Lys residues in its close spatial proximity (K115E, K118E, and K123E). The results obtained support the general conclusion that HtA active site would show a high degree of plasticity, being able to accommodate electrostatic and structural changes not suitable for the other previously known larger ribotoxins, as the variants described here only presented small differences in terms of ribonucleolytic activity and cytotoxicity against cultured insect cells.

scholarly journals Transcriptional repression by wild-type p53 utilizes histone deacetylases, mediated by interaction with mSin3a

1999 ◽  
Vol 13 (19) ◽  
pp. 2490-2501 ◽  
Author(s):  
M. Murphy ◽  
J. Ahn ◽  
K. K. Walker ◽  
W. H. Hoffman ◽  
R. M. Evans ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Histone Deacetylases ◽  
Wild Type ◽  
Wild Type P53

scholarly journals Functional Interaction between Class II Histone Deacetylases and ICP0 of Herpes Simplex Virus Type 1

2004 ◽  
Vol 78 (13) ◽  
pp. 6744-6757 ◽  
Author(s):  
Patrick Lomonte ◽  
Joëlle Thomas ◽  
Pascale Texier ◽  
Cécile Caron ◽  
Saadi Khochbin ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Histone Deacetylases ◽  
Class Ii ◽  
Class I ◽  
Transfected Cells ◽  
Amino Terminal ◽  
Simplex Virus ◽  
Class I Hdacs

ABSTRACT This study describes the physical and functional interactions between ICP0 of herpes simplex virus type 1 and class II histone deacetylases (HDACs) 4, 5, and 7. Class II HDACs are mainly known for their participation in the control of cell differentiation through the regulation of the activity of the transcription factor MEF2 (myocyte enhancer factor 2), implicated in muscle development and neuronal survival. Immunofluorescence experiments performed on transfected cells showed that ICP0 colocalizes with and reorganizes the nuclear distribution of ectopically expressed class I and II HDACs. In addition, endogenous HDAC4 and at least one of its binding partners, the corepressor protein SMRT (for silencing mediator of retinoid and thyroid receptor), undergo changes in their nuclear distribution in ICP0-transfected cells. As a result, during infection endogenous HDAC4 colocalizes with ICP0. Coimmunoprecipitation and glutathione S-transferase pull-down assays confirmed that class II but not class I HDACs specifically interacted with ICP0 through their amino-terminal regions. This region, which is not conserved in class I HDACs but homologous to the MITR (MEF2-interacting transcription repressor) protein, is responsible for the repression, in a deacetylase-independent manner, of MEF2 by sequestering it under an inactive form in the nucleus. Consequently, we show that ICP0 is able to overcome the HDAC5 amino-terminal- and MITR-induced MEF2A repression in gene reporter assays. This is the first report of a viral protein interacting with and controlling the repressor activity of class II HDACs. We discuss the putative consequences of such an interaction for the biology of the virus both during lytic infection and reactivation from latency.

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