In the absence of H2A.Z, the SWR1 histone replacement complex causes genetic instability, stress and genome transcription misregulation
Ontology highlight
ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae Schizosaccharomyces pombe
PROVIDER: GSE21571 | GEO | 2011/05/18
SECONDARY ACCESSION(S): PRJNA127007
REPOSITORIES: GEO
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Project description:The SWR1 complex replaces the canonical histone H2A with the variant H2A.Z (Htz1 in yeast) at specific chromatin regions. This dynamic alteration in nucleosome structure provides a molecular mechanism to regulate transcription. Here we analysed the transcription profiles of single and double mutants and wild-type cells by whole-genome microarray analysis. Our results indicate that genome-wide transcriptional misregulation in htz1∆ can be partially or totally suppressed if SWR1 is not formed (swr1∆), if it forms but cannot bind to chromatin (swc2∆), or if it binds to chromatin but has no histone replacement activity (swc5∆). These results suggest that in htz1∆ the nucleosome remodelling activity of SWR1 affects chromatin integrity because of an attempt to replace H2A with Htz1 in the absence of the latter. Three biological independent replicates were use for each strain
2011-05-18 | E-GEOD-21571 | biostudies-arrayexpress
Project description:Histone variant H2A.Z-containing nucleosomes are incorporated at most eukaryotic promoters. This incorporation is mediated by the conserved SWR1 complex, which replaces histone H2A in canonical nucleosomes with H2A.Z in an ATP-dependent manner. Here, we show that promoter-proximal nucleosomes are highly heterogeneous for H2A.Z in Saccharomyces cerevisiae, with substantial representation of nucleosomes containing one, two, or no H2A.Z molecules. SWR1-catalyzed H2A.Z replacement in vitro occurs in a stepwise and unidirectional fashion, one H2A.Z-H2B dimer at a time, producing heterotypic nucleosomes as intermediates and homotypic H2A.Z nucleosomes as end products. The ATPase activity of SWR1 is specifically stimulated by H2A-containing nucleosomes without ensuing histone H2A eviction. Remarkably, further addition of free H2A.Z-H2B dimer leads to hyperstimulation of ATPase activity, eviction of nucleosomal H2A-H2B and deposition of H2A.Z-H2B. These results suggest that the combination of H2A-containing nucleosome and free H2A.Z-H2B dimer acting as both effector and substrate for SWR1 governs the specificity and outcome of the replacement reaction. Total nucleosomes from MNase-treated nuclear extracts were fractionated by sequential immunoprecipitation into homotypic H2A/H2A (AA), heterotypic H2A/H2A.Z (AZ), and homotypic H2A.Z/H2A.Z (ZZ) nucleosomes.
2010-10-12 | E-GEOD-24618 | biostudies-arrayexpress
Project description:Histone variant H2A.Z-containing nucleosomes are incorporated at most eukaryotic promoters. This incorporation is mediated by the conserved SWR1 complex, which replaces histone H2A in canonical nucleosomes with H2A.Z in an ATP-dependent manner. Here, we show that promoter-proximal nucleosomes are highly heterogeneous for H2A.Z in Saccharomyces cerevisiae, with substantial representation of nucleosomes containing one, two, or no H2A.Z molecules. SWR1-catalyzed H2A.Z replacement in vitro occurs in a stepwise and unidirectional fashion, one H2A.Z-H2B dimer at a time, producing heterotypic nucleosomes as intermediates and homotypic H2A.Z nucleosomes as end products. The ATPase activity of SWR1 is specifically stimulated by H2A-containing nucleosomes without ensuing histone H2A eviction. Remarkably, further addition of free H2A.Z-H2B dimer leads to hyperstimulation of ATPase activity, eviction of nucleosomal H2A-H2B and deposition of H2A.Z-H2B. These results suggest that the combination of H2A-containing nucleosome and free H2A.Z-H2B dimer acting as both effector and substrate for SWR1 governs the specificity and outcome of the replacement reaction.
2010-10-12 | GSE24618 | GEO
Project description:Actin-related proteins are ubiquitous components of chromatin remodelers, and are conserved from yeast to man. We have examined the role of the budding yeast actin-related protein Arp6 in gene expression, both as a component of the SWR1 complex (SWR-C) and in its absence. We mapped Arp6-binding sites genome-wide using chromatin immunoprecipitation in mutant and wild-type cells. We find that the majority of Arp6-binding sites in euchromatin coincide with binding sites of Swr1, the catalytic subunit of SWR-C, and with the histone H2A variant Htz1. However, the remaining Arp6 binding in telomeres, centromeres, and the promoters of ribosomal protein (RP) genes are independent of Swr1 and Htz1 deposition. We show that Arp6 can position chromatin at nuclear pores, and is required for the pore association of the RP genes to which it binds. This anchoring is also independent of Swr1. Loss of Arp6, but not Htz1, leads to an up-regulation of RP genes and loss of relocalization. This is in contrast to the Htz1-mediated pore-association of GAL1, for which loss of Arp6 impairs activation. Given that Arp6 is required for SWR-C dependent deposition of Htz1, we conclude that Arp6 contributes to both H2AZ-dependent and H2AZ-independent association with nuclear pores and subsequent effects on gene expression. These data illustrate how nuclear actin-related proteins contribute to the long-range organization of chromatin domains in the interphase nucleus. Four replicates for the arp6 deletion mutant and three replicates for the swr1 deletion mutant compared to wild-type.
2010-05-01 | E-GEOD-17780 | biostudies-arrayexpress
Project description:Actin-related proteins are ubiquitous components of chromatin remodelers, and are conserved from yeast to man. We have examined the role of the budding yeast actin-related protein Arp6 in gene expression, both as a component of the SWR1 complex (SWR-C) and in its absence. We mapped Arp6-binding sites genome-wide using chromatin immunoprecipitation in mutant and wild-type cells. We find that the majority of Arp6-binding sites in euchromatin coincide with binding sites of Swr1, the catalytic subunit of SWR-C, and with the histone H2A variant Htz1. However, the remaining Arp6 binding in telomeres, centromeres, and the promoters of ribosomal protein (RP) genes are independent of Swr1 and Htz1 deposition. We show that Arp6 can position chromatin at nuclear pores, and is required for the pore association of the RP genes to which it binds. This anchoring is also independent of Swr1. Loss of Arp6, but not Htz1, leads to an up-regulation of RP genes and loss of relocalization. This is in contrast to the Htz1-mediated pore-association of GAL1, for which loss of Arp6 impairs activation. Given that Arp6 is required for SWR-C dependent deposition of Htz1, we conclude that Arp6 contributes to both H2AZ-dependent and H2AZ-independent association with nuclear pores and subsequent effects on gene expression. These data illustrate how nuclear actin-related proteins contribute to the long-range organization of chromatin domains in the interphase nucleus.
2010-05-01 | GSE17780 | GEO
Project description:The histone variant H2A.Z is a genome-wide signature of nucleosomes proximal to eukaryotic regulatory DNA. While the multi-subunit SWR1 chromatin remodeling complex is known to catalyze ATP-dependent deposition of H2A.Z, the mechanism of recruitment to S. cerevisiae promoters has been unclear. A sensitive assay for competitive binding of di-nucleosome substrates revealed that SWR1 preferentially binds long nucleosome-free DNA adjoining core particles, allowing discrimination of gene promoters over gene bodies. We traced the critical DNA binding component of SWR1 to the conserved Swc2/YL1 subunit, whose activity is required for both SWR1 binding and H2A.Z incorporation in vivo. Histone acetylation by NuA4 enhances SWR1 binding, but the interaction with nucleosome-free DNA is the major determinant. ‘Hierarchical cooperation’ between high affinity DNA- and low affinity histone modification-binding factors may reconcile the large disparity in affinities for chromatin substrates, and unify classical control by DNA-binding factors with post-translational histone modifications and ATP-dependent nucleosome mobility. Swr1 TAP IF of various mutants
2013-09-16 | E-GEOD-49183 | biostudies-arrayexpress
Project description:The site-specific chromatin incorporation of eukaryotic histone variant H2A.Z is driven by the multi-component chromatin remodeling complex SWR1/SRCAP/ p400. The budding yeast SWR1 complex replaces the H2A-H2B dimer in the canonical nucleosome with the H2A.Z-H2B dimer, but the mechanism governing the directionality of H2A-to-H2A.Z exchange remains elusive. Here, we use single-molecule force spectroscopy to dissect the disassembly/ reassembly of H2A-nucleosome and H2A.Z-nucleosome. We find that the N-terminal 1-135 residues of yeast SWR1-complex-protein-2 (previously termed Swc2-Z) facilitate the disassembly of nucleosomes containing H2A but not H2A.Z. The Swc2-mediated nucleosome disassembly/reassembly requires the inherently unstable H2A-nucleosome, whose instability is conferred by three H2A α2-helix residues Gly47, Pro49 and Ile63 as they selectively weaken the structural rigidity of H2A-H2B dimer. It also requires Swc2-ZN (residues 1-37) that directly anchors to H2A-nucleosome and functions in the SWR1-catalyzed H2A.Z replacement in vitro and yeast H2A.Z deposition in vivo. Our findings providecrucial insights into how SWR1 complex discriminates between the H2A-nucleosome and H2A.Z-nucleosome, establishing a simple paradigm for the governace of unidirectional H2A.Z exchange.
2021-04-12 | GSE171844 | GEO
Project description:The histone variant H2A.Z is a genome-wide signature of nucleosomes proximal to eukaryotic regulatory DNA. While the multi-subunit SWR1 chromatin remodeling complex is known to catalyze ATP-dependent deposition of H2A.Z, the mechanism of recruitment to S. cerevisiae promoters has been unclear. A sensitive assay for competitive binding of di-nucleosome substrates revealed that SWR1 preferentially binds long nucleosome-free DNA adjoining core particles, allowing discrimination of gene promoters over gene bodies. We traced the critical DNA binding component of SWR1 to the conserved Swc2/YL1 subunit, whose activity is required for both SWR1 binding and H2A.Z incorporation in vivo. Histone acetylation by NuA4 enhances SWR1 binding, but the interaction with nucleosome-free DNA is the major determinant. ‘Hierarchical cooperation’ between high affinity DNA- and low affinity histone modification-binding factors may reconcile the large disparity in affinities for chromatin substrates, and unify classical control by DNA-binding factors with post-translational histone modifications and ATP-dependent nucleosome mobility.
2013-09-16 | GSE49183 | GEO
Project description:The SWR1 chromatin remodeling complex (SRCAP in humans) is recruited to +1 nucleosomes downstream of transcription start sites of eukaryotic promoters, where it exchanges histone H2A for the specialized variant H2A.Z. Here we use cryo-EM to resolve the structural basis of the SWR1 interaction with free DNA, revealing a distinct open conformation of the Swr1 ATPase that enables sliding from accessible DNA to nucleosomes. A complete structural model of the SWR1-nucleosome complex illustrates critical structure-function roles for Swc2 and Swc3 subunits in oriented nucleosome engagement by SWR1. Moreover, an extended DNA-binding α -helix within the Swc3 subunit enables sensing of nucleosome linker length and is essential for SWR1 promoter-specific recruitment and activity. The previously unresolved N-SWR1 subcomplex forms a flexible extended structure enabling multivalent recognition of acetylated histone tails by reader domains to further direct SWR1 towards the +1 nucleosome. Altogether, our findings provide a generalizable mechanism for promoter-specific targeting of chromatin and transcription complexes.
2024-08-26 | GSE275429 | GEO
Project description:A cascade of histone acetylation events with subsequent incorporation of a histone H2A variant plays an essential part in transcription regulation in various model organisms. A key player in this cascade is the chromatin remodellling complex SWR1, which replaces the canonical histone H2A with its variant H2A.Z. Transcriptional regulation of polycistronic transcription units in the unicellular parasite Trypanosoma brucei has been shown to be highly dependent on acetylation of H2A.Z, which is mediated by the histone-acetyltransferase HAT2. The chromatin remodellling complex, which mediates H2A.Z incorporation is not known and an SWR1 orthologue in trypanosomes has not yet been reported. In this study, we identified and characterised an SWR1-like remodelller complex in T. brucei that is responsible for Pol II-dependent transcriptional regulation. Bioinformatic analysis of potential SNF2 DEAD/Box helicases, the key component of SWR1 complexes, identified a 1211 amino acids-long protein that exhibits key structural characteristics of the SWR1 subfamily. Systematic protein-protein interaction analysis revealed the existence of a novel complex exhibiting key features of an SWR1-like chromatin remodelller. RNAi-mediated depletion of the ATPase subunit of this complex resulted in a significant reduction of H2A.Z incorporation at transcription start sites and a subsequent decrease of steady-state mRNA levels. Furthermore, depletion of SWR1 and RNA-polymerase II (Pol II) caused massive chromatin condensation. The potential function of several proteins associated with the SWR1-like complex and with HAT2, the key factor of H2A.Z incorporation, is discussed.
2022-08-12 | PXD026796 | Pride