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Sub1 and RPA associate with RNA Polymerase II at different stages of transcription

ABSTRACT: Single stranded DNA binding proteins play many roles in nucleic acid metabolism, but their importance during transcription remains unclear. Quantitative proteomic analysis of RNA polymerase II (RNApII) pre-initiation complexes (PICs) identified Sub1 and the Replication Protein A complex (RPA), both of which bind single-stranded DNA (ssDNA). Sub1, homolog of mammalian coactivator PC4, exhibits strong genetic interactions with factors necessary for promoter melting. Sub1 localizes near the transcription bubble in vitro and binds to promoters in vivo dependent upon PIC assembly. In contrast, RPA localizes to transcribed regions of active genes, strongly correlated with transcribing RNApII but independently of replication. RFA1 interacts genetically with transcription elongation factor genes. Interestingly, RPA levels increase at active promoters in cells carrying a Sub1 deletion or ssDNA binding mutant, suggesting competition for a common binding site. We propose that Sub1 and RPA interact with the non-template strand of RNApII complexes during initiation and elongation, respectively.

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE32416 | GEO | 2011/09/27

SECONDARY ACCESSION(S): PRJNA147897

REPOSITORIES: GEO

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Sub1 and RPA associate with RNA Polymerase II at different stages of transcription

Project description:Single stranded DNA binding proteins play many roles in nucleic acid metabolism, but their importance during transcription remains unclear. Quantitative proteomic analysis of RNA polymerase II (RNApII) pre-initiation complexes (PICs) identified Sub1 and the Replication Protein A complex (RPA), both of which bind single-stranded DNA (ssDNA). Sub1, homolog of mammalian coactivator PC4, exhibits strong genetic interactions with factors necessary for promoter melting. Sub1 localizes near the transcription bubble in vitro and binds to promoters in vivo dependent upon PIC assembly. In contrast, RPA localizes to transcribed regions of active genes, strongly correlated with transcribing RNApII but independently of replication. RFA1 interacts genetically with transcription elongation factor genes. Interestingly, RPA levels increase at active promoters in cells carrying a Sub1 deletion or ssDNA binding mutant, suggesting competition for a common binding site. We propose that Sub1 and RPA interact with the non-template strand of RNApII complexes during initiation and elongation, respectively. Chip-chip from wt and sub1D cells with Rfa1 Chromatin immunoprecipitation (ChIP) of Rfa1 in wt and sub1D yeast demonstrated that Rfa1 localization correlates with RNA Polymerase II and is increased at some transcription start sites when Sub1 has been deleted. Comparison of Rfa1 localization in wt vs sub1D yeast

2011-09-26 | E-GEOD-32416 | biostudies-arrayexpress

Phase separation properties of RPA combine high-affinity ssDNA binding with dynamic condensate functions at telomeres

Project description:RPA has been shown to protect single-stranded DNA (ssDNA) intermediates from instability and breakage. RPA binds ssDNA with sub-nanomolar affinity, yet dynamic turnover is required for downstream ssDNA transactions. How ultrahigh-affinity binding and dynamic turnover are achieved simultaneously is not well understood. Here we reveal that RPA has a strong propensity to assemble into dynamic condensates. In solution, purified RPA phase separates into liquid droplets with fusion and surface wetting behavior. Phase separation is stimulated by sub-stoichiometric amounts of ssDNA, but not RNA or double-stranded DNA, and ssDNA gets selectively enriched in RPA condensates. We find the RPA2 subunit required for condensation and multi-site phosphorylation of the RPA2 N-terminal intrinsically disordered region to regulate RPA self-interaction. Functionally, quantitative proximity proteomics links RPA condensation to telomere clustering and integrity in cancer cells. Collectively, our results suggest that RPA-coated ssDNA is contained in dynamic RPA condensates whose properties are important for genome organization and stability.

2023-03-15 | PXD036935 | Pride

Rtt105 promotes DNA replication by functioning as an RPA chaperone

Project description:Single-stranded DNA (ssDNA) binding protein Replication Protein A (RPA) is essential for protecting ssDNA at replication forks. However, how RPA is loaded to replication forks remains unexplored. Here, we show that Regulator of Ty1 transposition protein 105 (Rtt105) binds RPA and is required for the association of RPA with replication forks. Cells lacking Rtt105 exhibit dramatic genome instability and severe defects in DNA replication. Intriguingly, both the RPA nuclear import and its ability to bind DNA replication forks were greatly compromised in rtt105 mutant cells, however, targeting RPA to the nucleus cannot rescue the defect of RPA binding to replication forks. Importantly, Rtt105 promotes the binding of RPA to ssDNA but does not associate with the final RPA-ssDNA complex in vitro. Moreover, single-molecule studies revealed that Rtt105 affects the binding mode of RPA to ssDNA. These results support a model in which Rtt105 functions as an RPA chaperone that escorts RPA to nucleus and assemble RPA onto ssDNA at replication forks.

2018-07-27 | GSE101536 | GEO

RPA promotes processive ssDNA digestion by Dna2 via their bimodal interaction in Saccharomyces cerevisiae

Project description:Single-stranded DNA (ssDNA) widely exists as intermediates in DNA metabolic pathways. The ssDNA binding protein, RPA, not only protects the integrity of ssDNA, but also directs the downstream factor that signals or repairs the ssDNA intermediate. However, it remains unclear how these enzymes/factors out-compete RPA and access to ssDNA. Using the budding yeast, Saccharomyces cerevisiae, as a model system, we discovered that Dna2, a key nuclease in DNA replication and repair, employs a bimodal interface to act with RPA both in cis and in trans. The cis-action renders RPA a processive unit for Dna2-catalyzed ssDNA digestion, where RPA actively delivers its bound ssDNA to Dna2. The trans-action mediated by an acidic patch from Dna2, on the other hand, enables Dna2 to operatie with a sub-optimal amount of RPA or to overcome DNA secondary structures. Genetically, this trans-action mode is not required for cell viability, but indispensable for successful DSB repair.

2022-02-22 | PXD028637 | Pride

Regulator of Ty1 transposition protein 105 (Rtt105) is an RPA chaperone and is required for genome stability maintenance

Project description:Single-stranded DNA (ssDNA) binding protein Replication Protein A (RPA) is essential for protecting ssDNA at replication forks. However, how RPA is guided to DNA replication forks remains unclear. Here, we show that Regulator of Ty1 transposition protein 105 (Rtt105) is an RPA-binding protein and is required for the binding of RPA at replication forks. Cells lacking Rtt105 exhibit extensive genome instability and severe defects in DNA replication. Both the nuclear import of RPA and the extent of genome-wide binding of RPA at replication forks were greatly compromised in rtt105 mutant cells. Mechanistically, Rtt105 is required for the interaction of RPA with Kap95, an importin protein known to be essential for RPA’s nuclear import. Remarkably, Rtt105 strongly enhances RPA binding with ssDNA substrates in vitro. We therefore propose a model in which Rtt105 functions as a RPA chaperone that both escorts RPA during nuclear important and delivers RPA to replication forks.

2018-07-27 | GSE87356 | GEO

RNA processing proteins regulate Mec1/ATR activation by promoting generation of RPA-coated ssDNA.

Project description:Eukaryotic cells respond to DNA double-strand breaks (DSBs) by activating a checkpoint that depends on the protein kinases Tel1/ATM and Mec1/ATR. Mec1/ATR is activated by RPA-coated single-stranded DNA (ssDNA), which arises upon nucleolytic degradation (resection) of the DSB. Emerging evidences indicate that RNA processing factors play critical, yet poorly understood, roles in genomic stability. Here, we provide evidence that the Saccharomyces cerevisiae RNA decay factors Xrn1, Rrp6 and Trf4 regulate Mec1/ATR activation by promoting generation of RPA-coated ssDNA. The lack of Xrn1 inhibits ssDNA generation at the DSB by preventing the loading of the MRX complex. By contrast, DSB resection is not affected in the absence of Rrp6 or Trf4, but their lack impairs the recruitment of RPA, and therefore of Mec1, to the DSB. Rrp6 and Trf4 inactivation affects neither Rad51/Rad52 association nor DSB repair by HR, suggesting that full Mec1 activation requires higher amount of RPA-coated ssDNA than HR-mediated repair. Noteworthy, deep transcriptome analyses do not identify common misregulated gene expression that could explain the observed phenotypes. Our results provide a novel link between RNA processing and genome stability. Strand-specific transcriptome analysis of biological replicates of WT cells (JKM139 strain) at T0, or 60 and 240 minutes after HO induction, and of xrn1∆, rrp6∆ and trf4∆ cells at T0.

2014-11-20 | E-GEOD-63444 | biostudies-arrayexpress

Effect of SUB1 knockdown on aggressive prostate cancer

Project description:SUB1 is known to be playing critical role in vital cellular processes such as DNA replication, repair and heterochromatization. Expression profiling studies in several cancers show its overexpression. However, its regulation and function in cancer has been less explored. Our study has indicated high expression of SUB1 in aggressive prostate cancer, we also found that the knockdown of SUB1 led to alterations in cell proliferation, invasion and migration. In addition, we found that mir-101, a tumor suppressor microRNA targets and regulates the expression of SUB1

2016-10-31 | GSE74895 | GEO

Chromatin Protein PC4 Orchestrates B Cell Differentiation by Collaborating with IKAROS and IRF4 (Agilent microarrays)

Project description:B cell development is orchestrated by various transcription factors collaborating with chromatin remodelers that determine the genomic architecture. However, chromatin regulation in mature B cells is still poorly understood. Here, we show the critical function of positive coactivator 4 (PC4), a bona fide non-histone chromatin protein encoded by Sub1. B-cell specific Sub1-deficient mice showed the decreased number and response against antigen stimulation of mature B cells. By combining PC4 chromatin immunoprecipitation-sequencing and complex purification, we identified transcription factor IKAROS as a partner of PC4 in gene regulation. PC4 and IKAROS cooperated to promote heterochromatin formation of their target gene loci and thereby established B cell identity. Importantly, PC4 stabilized IKAROS protein in mature B cells and inhibited IKAROS degradation by the anti-cancer drug lenalidomide in human B-cell lymphoma cells. These findings establish PC4 as not only a chromatin regulator of B cells but also a new therapeutic target in B-cell malignancies.

2020-12-22 | GSE145952 | GEO

Chromatin Protein PC4 Orchestrates B Cell Differentiation by Collaborating with IKAROS and IRF4 (ChIP-seq)

2020-12-22 | GSE145951 | GEO

Sub1 occupancy in yeast cells in exponential growth condition

Project description:A genome-wide location analysis by ChIP on chip of the gene occupancy by Sub1 was undertaken to define the gene targets of Sub1 in vivo. Chromatin immunoprecipitation (ChIP) assays were performed on epitope-tagged Sub1-3HA cross-linked chromatin from exponentially growing cells. Immunopurified DNA and DNA from whole-cell extracts were fluorescently labelled and competitively hybridized to DNA microarrays harbouring ORFs and intergenic regions. The ratio of fluorescence intensities at each site in the microarray provided a measure of the extent of Sub1 binding to a specific genomic locus. Data from three independent experiments were compiled. Many loci were found to be significantly enriched in active growth conditions where Sub1 is not essential for cell viability. Approximately one-fourth of the enriched loci were located within ORF and the others corresponded to intergenic regions and to genes encoding non-translated RNAs. The ACT1, PMA1, PYK1, ADH1 and snoRNA genes previously identified as DNA targets of Sub1 were indeed enriched in our data. Sub1 was also preferentially bound to a subset of Pol II-transcribed genes encoding constituents of the cell wall, the nucleosome and the ribosome. Remarkably, these Pol II genes represented only two-third of the enriched loci. The other ones corresponded to Pol III-transcribed genes present on the arrays or to the intergenic regions and ORFs adjacent to these genes, suggesting the association of Sub1 to all Pol III-transcribed genes in conditions of active growth. The arrays used had a poor coverage of the rDNA gene locus. Nevertheless, we found a significant enrichment of the different loci corresponding to that region suggesting that Sub1 associates at many locations throughout the rDNA gene. Altogether, the results suggested that Sub1 could be a regulator of all three transcription systems. Keywords: ChIP-Chip

2009-08-27 | GSE11054 | GEO

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