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)

The glycosylase/abasic lyase T4 endonuclease V initiates the repair of ultraviolet light-induced pyrimidine dimers. This enzyme forms an imino intermediate between its N-terminal alpha-NH2 group and C-1' of the 5'-residue within the dimer. Sodium borohydride was used to covalently trap endonuclease V to a 49-base pair oligodeoxynucleotide containing a site-specific cyclobutane thymine dimer. The bound and free oligonucleotides were then subjected to nuclease protection assays using DNase I and a complex of 1,10-phenanthroline-copper. There was a large region of protection from both nucleases produced by endonuclease V evident on the strand opposite and asymmetrically opposed to the dimer. Little protection was seen on the dimer-containing strand. The existence of a footprint with the 1,10-phenanthroline-copper cleavage agent indicated that endonuclease V was interacting with the DNA predominantly via the minor groove. Methylation by dimethyl sulfate yielded no areas of protection when endonuclease V was covalently attached to the DNA, indicating that the protein may closely approach the DNA without direct contact with the bases near the thymine dimer. The Escherichia coli proteins Fpg and photolyase display a very different pattern of nuclease protection on their respective substrates, implying that endonuclease V recognizes pyrimidine dimers by a novel mechanism.
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PMID:T4 endonuclease V protects the DNA strand opposite a thymine dimer from cleavage by the footprinting reagents DNase I and 1,10-phenanthroline-copper. 787 17

The relationship between purified transcription factor p50 binding and ultraviolet light-induced DNA damage formation in the NF-kappa B promoter element was investigated. The effect of bound transcription factor on cyclobutane dimer formation was quantified using Maxam-Gilbert analysis of irradiated substrate digested with T4 phage endonuclease V. Two methods were employed for cleaving (6-4) photoproducts. Sites of (6-4) photoproducts cleaved by piperidine showed a general suppression in the presence of bound p50 protein similar to that observed for cyclobutane dimers. In contrast to piperidine, digestion with ultraviolet damage endonuclease (UVDE) from Saccharomyces pombe subsequent to cyclobutane dimer reversal by photolyase displayed a broader spectrum of damaged sites. Whereas some of these sites were suppressed by bound p50 protein, some remained unaffected and one site showed increased (6-4) photoproduct induction. These data illustrate the advantage of UVDE over piperidine for studying (6-4) photoproducts at the sequence level and suggest that this approach may be useful for footprinting transcription factor binding in other promoters.
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PMID:Bound transcription factor suppresses photoproduct formation in the NF-kappa B promoter. 1120 59