Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.99.3 (PRE)
 1,923 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A current model for transcription-coupled DNA repair is that RNA polymerase, arrested at a DNA lesion, directs the repair machinery to the transcribed strand of an active gene. To help elucidate this role of RNA polymerase, we constructed DNA templates containing the major late promoter of adenovirus and a cyclobutane pyrimidine dimer (CPD) at a specific site. CPDs, the predominant DNA lesions formed by ultraviolet radiation, are good substrates for transcription-coupled repair. A CPD located on the transcribed strand of the template was a strong block to polymerase movement, whereas a CPD located on the nontranscribed strand had no effect on transcription. Furthermore, the arrested polymerase shielded the CPD from recognition by photolyase, a bacterial DNA repair protein. Transcription elongation factor SII (also called TFIIS) facilitates read-through of a variety of transcriptional pause sites by a process in which RNA polymerase II cleaves the nascent transcript before elongation resumes. We show that SII induces nascent transcript cleavage by RNA polymerase II stalled at a CPD. However, this cleavage does not remove the arrested polymerase from the site of the DNA lesion, nor does it facilitate translesional bypass by the polymerase. The arrested ternary complex is stable and competent to resume elongation, demonstrating that neither the polymerase nor the RNA product dissociates from the DNA template.
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PMID:Transcript cleavage by RNA polymerase II arrested by a cyclobutane pyrimidine dimer in the DNA template. 807 11

We have characterized the properties of immunopurified transcription complexes arrested at a specifically located cyclobutane pyrimidine dimer (CPD) using enzymatic probes and an in vitro transcription system with purified RNA polymerase II (RNAP II) and initiation factors. To help understand how RNAP II distinguishes between a natural impediment and a lesion in the DNA to initiate a repair event, we have compared the conformation of RNAP II complexes arrested at a CPD with complexes arrested at a naturally occurring elongation impediment. The footprint of RNAP II arrested at a CPD, using exonuclease III and T4 DNA polymerase's 3'-->5' exonuclease, covers approximately 35 base pairs and is asymmetrically located around the dimer. A similar footprint is observed when RNAP II is arrested at the human histone H3.3 arrest site. Addition of elongation factor SII to RNAP II arrested at a CPD produced shortened transcripts of discrete lengths up to 25 nucleotides shorter than those seen without SII. After addition of photolyase and exposure to visible light, some of the transcripts could be reelongated beyond the dimer, suggesting that SII-mediated transcript cleavage accompanied significant RNAP II backup, thereby providing access of the repair enzyme to the arresting CPD.
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PMID:Structural characterization of RNA polymerase II complexes arrested by a cyclobutane pyrimidine dimer in the transcribed strand of template DNA. 1044 84