Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Histone modifications play an important role in transcription. We previously studied histone H2B ubiquitylation on lysine 123 and subsequent deubiquitylation by SAGA-associated Ubp8. Unlike other histone modifications, both the addition and removal of ubiquitin are required for optimal transcription. Here we report that deubiquitylation of H2B is important for recruitment of a complex containing the kinase Ctk1, resulting in phosphorylation of the RNA polymerase II (Pol II) C-terminal domain (CTD), and for subsequent recruitment of the Set2 methyltransferase. We find that Ctk1 interacts with histones H2A and H2B, and that persistent H2B ubiquitylation disrupts these interactions. We further show that Ubp8 enters the GAL1 coding region through an interaction with Pol II. These findings reveal a mechanism by which H2B ubiquitylation acts as a barrier to Ctk1 association with active genes, while subsequent deubiquitylation by Ubp8 triggers Ctk1 recruitment at the appropriate point in activation.
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PMID:H2B ubiquitylation acts as a barrier to Ctk1 nucleosomal recruitment prior to removal by Ubp8 within a SAGA-related complex. 1764 76

The yeast Paf1 complex consists of Paf1, Rtf1, Cdc73, Ctr9, and Leo1 and regulates histone H2B ubiquitination, histone H3 methylation, RNA polymerase II carboxy-terminal domain (CTD) Ser2 phosphorylation, and RNA 3' end processing. We provide structural insight into the Paf1 complex with the NMR structure of the conserved and functionally important Plus3 domain of human Rtf1. A predominantly beta-stranded subdomain displays structural similarity to Dicer/Argonaute PAZ domains and to Tudor domains. We further demonstrate that the highly basic Rtf1 Plus3 domain can interact in vitro with single-stranded DNA via residues on the rim of the beta sheet, reminiscent of siRNA binding by PAZ domains, but did not detect binding to double-stranded DNA or RNA. We discuss the potential role of Rtf1 Plus3 ssDNA binding during transcription elongation.
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PMID:Structure and DNA binding of the human Rtf1 Plus3 domain. 1818 92

The monoubiquitylation of histone H2B has been associated with transcription initiation and elongation, but its role in these processes is poorly understood. We report that H2B ubiquitylation is required for efficient reassembly of nucleosomes during RNA polymerase II (Pol II)-mediated transcription elongation in yeast. This role is carried out in cooperation with the histone chaperone Spt16, and in the absence of H2B ubiquitylation and functional Spt16, chromatin structure is not properly restored in the wake of elongating Pol II. Moreover, H2B ubiquitylation and Spt16 play a role in each other's regulation. H2B ubiquitylation is required for the stable accumulation of Spt16 at the GAL1 coding region, and Spt16 regulates the formation of ubiquitylated H2B both globally and at the GAL1 gene. These data provide a mechanism linking H2B ubiquitylation to Spt16 in the regulation of nucleosome dynamics during transcription elongation.
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PMID:H2B ubiquitylation plays a role in nucleosome dynamics during transcription elongation. 1861 40

This work examines the role of the Arabidopsis thaliana RING E3 ligase, HISTONE MONOUBIQUITINATION1 (HUB1) in disease resistance. Loss-of-function alleles of HUB1 show increased susceptibility to the necrotrophic fungal pathogens Botrytis cinerea and Alternaria brassicicola, whereas HUB1 overexpression conferred resistance to B. cinerea. By contrast, responses to the bacterial pathogen Pseudomonas syringae are unaltered in hub1 plants. hub1 mutants have thinner cell walls but increased callose around an infection site. HUB1 acts independently of jasmonate, but ethylene (ET) responses and salicylate modulate the resistance of hub1 mutants to necrotrophic fungi. The ET response factor ETHYLENE INSENSITIVE2 is epistatic to HUB1 for A. brassicicola resistance but additive to HUB1 for B. cinerea resistance. HUB1 interacts with MED21, a subunit of the Arabidopsis Mediator, a conserved complex that regulates RNA polymerase II. RNA interference lines with reduced MED21 expression are highly susceptible to A. brassicicola and B. cinerea, whereas T-DNA insertion alleles are embryonic lethal, suggesting an essential role for MED21. However, HUB1-mediated histone H2B modification is independent of histone H3 and DNA methylation. In sum, histone H2B monoubiquitination is an important chromatin modification with regulatory roles in plant defense against necrotrophic fungi most likely through modulation of gene expression.
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PMID:HISTONE MONOUBIQUITINATION1 interacts with a subunit of the mediator complex and regulates defense against necrotrophic fungal pathogens in Arabidopsis. 1928 69

Elongation by RNA polymerase II (RNAPII) is a finely regulated process in which many elongation factors contribute to gene regulation. Among these factors are the polymerase-associated factor (PAF) complex, which associates with RNAPII, and several cyclin-dependent kinases, including positive transcription elongation factor b (P-TEFb) in humans and BUR kinase (Bur1-Bur2) and C-terminal domain (CTD) kinase 1 (CTDK1) in Saccharomyces cerevisiae. An important target of P-TEFb and CTDK1, but not BUR kinase, is the CTD of the Rpb1 subunit of RNAPII. Although the essential BUR kinase phosphorylates Rad6, which is required for histone H2B ubiquitination on K123, Rad6 is not essential, leaving a critical substrate(s) of BUR kinase unidentified. Here we show that BUR kinase is important for the phosphorylation in vivo of Spt5, a subunit of the essential yeast RNAPII elongation factor Spt4/Spt5, whose human orthologue is DRB sensitivity-inducing factor. BUR kinase can also phosphorylate the C-terminal region (CTR) of Spt5 in vitro. Like BUR kinase, the Spt5 CTR is important for promoting elongation by RNAPII and recruiting the PAF complex to transcribed regions. Also like BUR kinase and the PAF complex, the Spt5 CTR is important for histone H2B K123 monoubiquitination and histone H3 K4 and K36 trimethylation during transcription elongation. Our results suggest that the Spt5 CTR, which contains 15 repeats of a hexapeptide whose consensus sequence is S[T/A]WGG[A/Q], is a substrate of BUR kinase and a platform for the association of proteins that promote both transcription elongation and histone modification in transcribed regions.
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PMID:Control of transcriptional elongation and cotranscriptional histone modification by the yeast BUR kinase substrate Spt5. 1936 74

The histone chaperone Vps75 forms a complex with, and stimulates the activity of, the histone acetyltransferase Rtt109. However, Vps75 can also be isolated on its own and might therefore possess Rtt109-independent functions. Analysis of epistatic miniarray profiles showed that VPS75 genetically interacts with factors involved in transcription regulation whereas RTT109 clusters with genes linked to DNA replication/repair. Additional genetic and biochemical experiments revealed a close relationship between Vps75 and RNA polymerase II. Furthermore, Vps75 is recruited to activated genes in an Rtt109-independent manner, and its genome-wide association with genes correlates with transcription rate. Expression microarray analysis identified a number of genes whose normal expression depends on VPS75. Interestingly, histone H2B dynamics at some of these genes are consistent with a role for Vps75 in histone H2A/H2B eviction/deposition during transcription. Indeed, reconstitution of nucleosome disassembly using the ATP-dependent chromatin remodeler Rsc and Vps75 revealed that these proteins can cooperate to remove H2A/H2B dimers from nucleosomes. These results indicate a role for Vps75 in nucleosome dynamics during transcription, and importantly, this function appears to be largely independent of Rtt109.
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PMID:An rtt109-independent role for vps75 in transcription-associated nucleosome dynamics. 1947 Jul 61

Post-translational histone modifications have essential roles in controlling nuclear processes; however, the specific mechanisms regulating these modifications and their combinatorial activities remain elusive. Cyclin-dependent kinase 9 (CDK9) regulates gene expression by phosphorylating transcriptional regulatory proteins, including the RNA polymerase II carboxy-terminal domain. Here, we show that CDK9 activity is essential for maintaining global and gene-associated levels of histone H2B monoubiquitination (H2Bub1). Furthermore, CDK9 activity and H2Bub1 help to maintain correct replication-dependent histone messenger RNA (mRNA) 3'-end processing. CDK9 knockdown consistently resulted in inefficient recognition of the correct mRNA 3'-end cleavage site and led to increased read-through of RNA polymerase II to an alternative downstream polyadenylation signal. Thus, CDK9 acts to integrate phosphorylation during transcription with chromatin modifications to control co-transcriptional histone mRNA processing.
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PMID:CDK9 directs H2B monoubiquitination and controls replication-dependent histone mRNA 3'-end processing. 1957 11

Transcription activation has been proposed to require both ubiquitylation and deubiquitylation of histone H2B. Here, we show that Lge1 (Large 1) is found in a complex containing Rad6.Bre1 and that it controls the recruitment of Bre1, a ubiquitin ligase, and Ubp8, a deubiquitylase, to promote ubiquitylation during the early steps in elongation. Chromatin immunoprecipitation experiments showed that Lge1 associates with promoter and coding regions of actively transcribed genes in a transcription-dependent manner. Disruption of Lge1 abolished ubiquitylation of histone H2B on lysine 123 and H3 methylation on lysines 4 and 79 and resulted in significant sensitivity to 6-azauracil and mycophenolic acid. In particular, in Lge1-deficient cells, Bre1 recruitment was attenuated, whereas recruitment of Ubp8 was facilitated. These alterations were coincident with changes in the interaction between Bre1.Ubp8 and RNA polymerase II phosphorylated at serine 5 of the C-terminal domain. We propose that Lge1 has a novel function in disrupting the balance between the recruitment of Bre1 and Ubp8, thus promoting transcription elongation.
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PMID:A Bre1-associated protein, large 1 (Lge1), promotes H2B ubiquitylation during the early stages of transcription elongation. 1992 26

The facilitates chromatin transcription (FACT) complex, consisting of the SSRP1 and SPT16 proteins, is a histone chaperone that assists the progression of transcribing RNA polymerase on chromatin templates by destabilizing nucleosomes. Here, we examined plants that harbour mutations in the genes encoding the subunits of Arabidopsis FACT. These experiments revealed that (i) SSRP1 is critical for plant viability, and (ii) plants with reduced amounts of SSRP1 and SPT16 display various defects in vegetative and reproductive development. Thus, mutant plants display an increased number of leaves and inflorescences, show early bolting, have abnormal flower and leaf architecture, and their seed production is severely affected. The early flowering of the mutant plants is associated with reduced expression of the floral repressor FLC in ssrp1 and spt16 plants. Compared to control plants, reduced amounts of FACT in mutant plants are detected at the FLC locus as well as at the locations of housekeeping genes (whose expression is not affected in the mutants), suggesting that expression of FLC is particularly sensitive to reduced FACT activity. Analysis of double mutants that are affected in the expression of both FACT subunits and factors catalysing the mono-ubiquitination of histone H2B (HUB1/2) demonstrates that they genetically interact to regulate various developmental processes (i.e. branching, leaf venation pattern, silique development) but independently regulate the growth of leaves and the induction of flowering.
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PMID:The transcript elongation factor FACT affects Arabidopsis vegetative and reproductive development and genetically interacts with HUB1/2. 2040 55

The mammalian adenosine monophosphate-activated protein kinase (AMPK) is a serine-threonine kinase protein complex that is a central regulator of cellular energy homeostasis. However, the mechanisms by which AMPK mediates cellular responses to metabolic stress remain unclear. We found that AMPK activates transcription through direct association with chromatin and phosphorylation of histone H2B at serine 36. AMPK recruitment and H2B Ser36 phosphorylation colocalized within genes activated by AMPK-dependent pathways, both in promoters and in transcribed regions. Ectopic expression of H2B in which Ser36 was substituted by alanine reduced transcription and RNA polymerase II association to AMPK-dependent genes, and lowered cell survival in response to stress. Our results place AMPK-dependent H2B Ser36 phosphorylation in a direct transcriptional and chromatin regulatory pathway leading to cellular adaptation to stress.
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PMID:Signaling kinase AMPK activates stress-promoted transcription via histone H2B phosphorylation. 2081 44


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