title: Enzymatic repair of pyrimidine dimer-containing DNA. A 5' dimer DNA glycosylase: 3'-apyrimidinic endonuclease mechanism from Micrococcus luteus.
abstract: A pyrimidine dimer-DNA glycosylase has been purified 20,000-fold from Micrococcus luteus. The enzyme is a single polypeptide chain with Mr = 18,000 that acts specifically on pyrimidine dimers, preferring those in double-stranded DNA to those in single-stranded DNA. The glycosylase cleaves the 5' residue of a pyrimidine dimer generating an apyrimidinic site and a mixed pyrimidine/pyrimidine nucleotide dimer. Under conditions of substrate excess, dimers containing a 5'-thymine are preferred to those with a 5'-cytosine residue. The glycosylase has an associated apyrimidinic/apurinic (AP) endonuclease that prefers apyrimidinic sites at the site of glycosylase action to either apurinic or apyrimidinic residues. This endonuclease is a Class I AP endonuclease in that it cleaves 3' to the AP site generating a 3'-deoxyribose moiety and a 5'-phosphate.
mesh_terms: D045647:DNA Glycosylases; D004260:DNA Repair; D004279:DNA, Viral / Q000528:radiation effects; D007700:Kinetics; D008837:Micrococcus / Q000201:enzymology*; D008970:Molecular Weight; D009699:N-Glycosyl Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D011740:Pyrimidine Dimers / Q000378:metabolism*; D013379:Substrate Specificity; D014466:Ultraviolet Rays
chemical_list: D004279:DNA, Viral; D011740:Pyrimidine Dimers; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C036401:deoxyribopyrimidine endonucleosidase