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)

The hereditary disease Cockayne syndrome (CS) is characterized by a complex clinical phenotype. CS cells are abnormally sensitive to ultraviolet radiation and are defective in the repair of transcriptionally active genes. The cloned CSB gene encodes a member of a protein family that includes the yeast Snf2 protein, a component of the transcriptional regulator Swi/Snf. We report the cloning of the CSA cDNA, which can encode a WD repeat protein. Mutations in the cDNA have been identified in CS-A cell lines. CSA protein interacts with CSB protein and with p44 protein, a subunit of the human RNA polymerase II transcription factor IIH. These observations suggest that the products of the CSA and CSB genes are involved in transcription.
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PMID:The Cockayne syndrome group A gene encodes a WD repeat protein that interacts with CSB protein and a subunit of RNA polymerase II TFIIH. 766 35

Cells from Cockayne's syndrome (CS) patients are sensitive to ultraviolet light and defective in preferential repair of the transcribed DNA strand. CS patients suffer from complex clinical symptoms, including severe growth retardation, neurological degeneration, mental retardation, and cachexia. Two CS complementation groups, CSA and CSB, have been identified so far. RAD26 encodes the yeast counterpart of the CSB gene. Here, we purify Rad26 protein to near homogeneity from yeast cells and show that it is a DNA-dependent ATPase. In contrast to the Mfd protein that functions in transcription-coupled repair in Escherichia coli, and which is a weak and DNA independent ATPase, Rad26 is a much more active ATPase, with a strict dependence on DNA. The possible role of Rad26 ATPase in the displacement of stalled RNA polymerase II from the site of the DNA lesion and in the subsequent recruitment of a DNA repair component is discussed.
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PMID:RAD26, the yeast homolog of human Cockayne's syndrome group B gene, encodes a DNA-dependent ATPase. 870 68

Multiple relationships have been noted between DNA repair and transcription in both prokaryotic and eukaryotic cells. First, in both prokaryotes and eukaryotes nucleotide excision repair of the template strand of transcriptionally active regions of the genome is faster than in the coding strand. In prokaryotes the biochemical basis for this kinetic difference appears to be related to the specific coupling of repair to arrested transcription by RNA polymerase. The biochemical basis for strand-specific repair in eukaryotes is unknown. Second, in eukaryotes some or all of the subunits of transcription factor IIH (TFIIH) are required for nucleotide excision repair. The biological significance of this dual function of TFIIH proteins is not obvious. Finally, there are indications that the genes CSA and CSB, which are implicated in the human hereditary disease Cockayne syndrome, may have a role in transcription.
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PMID:Relationships between DNA repair and transcription. 881 Nov 73

Damage to actively transcribed DNA is preferentially repaired by the transcription-coupled repair (TCR) system. TCR requires RNA polymerase II (Pol II), but the mechanism by which repair enzymes preferentially recognize and repair DNA lesions on Pol II-transcribed genes is incompletely understood. Herein we demonstrate that a fraction of the large subunit of Pol II (Pol II LS) is ubiquitinated after exposing cells to UV-radiation or cisplatin but not several other DNA damaging agents. This novel covalent modification of Pol II LS occurs within 15 min of exposing cells to UV-radiation and persists for about 8-12 hr. Ubiquitinated Pol II LS is also phosphorylated on the C-terminal domain. UV-induced ubiquitination of Pol II LS is deficient in fibroblasts from individuals with two forms of Cockayne syndrome (CS-A and CS-B), a rare disorder in which TCR is disrupted. UV-induced ubiquitination of Pol II LS can be restored by introducing cDNA constructs encoding the CSA or CSB genes, respectively, into CS-A or CS-B fibroblasts. These results suggest that ubiquitination of Pol II LS plays a role in the recognition and/or repair of damage to actively transcribed genes. Alternatively, these findings may reflect a role played by the CSA and CSB gene products in transcription.
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PMID:UV-induced ubiquitination of RNA polymerase II: a novel modification deficient in Cockayne syndrome cells. 887 79

In humans, DNA lesions such as pyrimidine dimers in the template strand of genes transcribed by RNA polymerase II are repaired faster than those in the coding strand and nontranscribed regions of the genome. This phenomenon, referred to as transcription-coupled repair (i) requires active transcription, (ii) does not require the XPC gene product which is essential for general/basal repair reactions, and (iii) requires the CSA and CSB proteins. We have developed an in vitro model system that consists of purified human excision repair factors and a DNA substrate analogous to a transcription bubble terminating at a cyclobutane thymine dimer. In this system the thymine dimer was excised independent of XPC. Furthermore, the thymine dimer in the bubble-containing substrate was removed approximately 3-fold faster by the excision repair nuclease reconstituted with or without XPC, compared with the removal of thymine dimer from a base paired duplex by the entire set of excision nuclease factors. These results provide important insight into the mechanism of transcription-coupled repair in humans.
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PMID:Model for XPC-independent transcription-coupled repair of pyrimidine dimers in humans. 906 8

The hereditary disease Cockayne syndrome (CS) is a complex clinical syndrome characterized by arrested post-natal growth as well as neurological and other defects. The CSA and CSB genes are implicated in this disease. The clinical features of CS can also accompany the excision repair-defective hereditary disorder xeroderma pigmentosum (XP) from genetic complementation groups B, D or G. The XPB and XPD proteins are subunits of RNA polymerase II (RNAP II) transcription factor IIH (TFIIH). We show here that extracts of CS-A and CS-B cells, as well as those from XP-B/CS cells, support reduced levels of RNAP II transcription in vitro and that this feature is dependent on the state or quality of the template.
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PMID:Reduced RNA polymerase II transcription in extracts of cockayne syndrome and xeroderma pigmentosum/Cockayne syndrome cells. 927 84

Transcription-coupled repair (TCR), a subpathway of nucleotide excision repair (NER) defective in Cockayne syndrome A and B (CSA and CSB), is responsible for the preferential removal of DNA lesions from the transcribed strand of active genes, permitting rapid resumption of blocked transcription. Here we demonstrate by microinjection of antibodies against CSB and CSA gene products into living primary fibroblasts, that both proteins are required for TCR and for recovery of RNA synthesis after UV damage in vivo but not for basal transcription itself. Furthermore, immunodepletion showed that CSB is not required for in vitro NER or transcription. Its central role in TCR suggests that CSB interacts with other repair and transcription proteins. Gel filtration of repair- and transcription-competent whole cell extracts provided evidence that CSB and CSA are part of large complexes of different sizes. Unexpectedly, there was no detectable association of CSB with several candidate NER and transcription proteins. However, a minor but significant portion (10-15%) of RNA polymerase II was found to be tightly associated with CSB. We conclude that within cell-free extracts, CSB is not stably associated with the majority of core NER or transcription components, but is part of a distinct complex involving RNA polymerase II. These findings suggest that CSB is implicated in, but not essential for, transcription, and support the idea that Cockayne syndrome is due to a combined repair and transcription deficiency.
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PMID:The Cockayne syndrome B protein, involved in transcription-coupled DNA repair, resides in an RNA polymerase II-containing complex. 931 53

Cockayne syndrome (CS) is characterized by impaired physical and mental development. Two complementation groups, CSA and CSB, have been identified. Here we report that the CSB gene product enhances elongation by RNA polymerase II. CSB stimulated the rate of elongation on an undamaged template by a factor of about 3. A thymine-thymine cyclobutane dimer located in the template strand is known to be a strong block to transcription. Addition of CSB to the blocked polymerase resulted in addition of one nucleotide to the nascent transcript. Finally, addition of transcription factor IIS is known to cause polymerase blocked at a thymine-thymine cyclobutane dimer to digest its nascent transcript, and CSB counteracted this transcript shortening action of transcription factor IIS. Thus a deficiency in transcription elongation may contribute to the CS phenotype.
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PMID:Cockayne syndrome group B protein enhances elongation by RNA polymerase II. 932 87

Cockayne's syndrome (CS) is a disease characterized by developmental and growth defects, sunlight sensitivity, and a defect in transcription-coupled nucleotide excision repair. The two principle proteins involved in CS, CSA and CSB/ERCC6, have been hypothesized to bind RNA polymerase II (Pol II) and link transcription to DNA repair. We have tested CSA and CSB in assays designed to determine their role in transcription-coupled repair. Using a unique oligo(dC)-tailed DNA template, we provide biochemical evidence that CSB/ERCC6 interacts with Pol II molecules engaged in ternary complexes containing DNA and nascent RNA. CSB is a DNA-activated ATPase, and hydrolysis of the ATP beta-gamma phosphoanhydride bond is required for the formation of a stable Pol II-CSB-DNA-RNA complex. Unlike CSB, CSA does not directly bind Pol II.
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PMID:Recruitment of the putative transcription-repair coupling factor CSB/ERCC6 to RNA polymerase II elongation complexes. 937 11

The known nucleotide excision repair (NER) defects of xeroderma pigmentosum (XP) and Cockayne syndrome (CS) cells can be exploited to analyze mechanisms of repair of UV-induced cyclobutane pyrimidine dimers (CPDs) at nucleotide (nt.) resolution. The two gene products of the CS complementation groups (CSA and CSB) have been implicated in the preferential repair of the transcribed strand of human genes. We had previously described very efficient repair of CPDs at sequences near the transcription initiation site of the human JUN gene in normal fibroblasts. Here, we have analyzed repair in a CSA fibroblast strain. CSA cells exhibited rapid repair near the transcription initiation site (positions -45 to +15) but were deficient in repair of sequences on the transcribed strand beginning around nt. +20. There was also no strand-selective repair of sequences further downstream of the start site (+260 to +450). The results suggest that the transcription-repair coupling factor (TRCF) CSA is required for efficient repair only during the elongation stages of RNA polymerase II transcription. We also discuss possible mechanisms of differential repair observed near the transcription initiation site in XP and CS cells and conclude that these in vivo repair data support some recent models obtained from nucleotide excision repair experiments in vitro.
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PMID:The transcription-repair coupling factor CSA is required for efficient repair only during the elongation stages of RNA polymerase II transcription. 968 18


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