title: Micrococcus luteus correndonucleases. II. Mechanism of action of two endonucleases specific for DNA containing pyrimidine dimers.
abstract: Py pyrimidine dimers Py correndonucleases I and II from Micrococcus luteus act exclusively on thymine-thymine, cytosine-cytosine, and thymine-cytosine cyclobutyl dimers in DNA, catalyzing incision 5' to the damage and generating 3'-hydroxyl and 5'-phosphoryl termini. Both enzymes initiate excision of pyrimidine dimers in vitro by correxonucleases and DNA polymerase I. The respective incised DNAs, however, differ in their ability to act as substrate for phage T4 polynucleotide ligase or bacterial alkaline phosphatase, suggesting that each endonuclease is specific for a conformationally unique  site. The possibility that their respective action generates termini which represent different degrees of single strandedness is suggested by the unequal protection by Escherichia coli binding protein from the hydrolytic action of exonuclease VII.
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D004247:DNA / Q000528:radiation effects; D003851:Deoxyribonucleases / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism*; D004926:Escherichia coli; D005092:Exonucleases / Q000378:metabolism; D008837:Micrococcus / Q000201:enzymology*; D011118:Polynucleotide Ligases; D011740:Pyrimidine Dimers; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D011740:Pyrimidine Dimers; D004247:DNA; D003851:Deoxyribonucleases; D004720:Endonucleases; D005092:Exonucleases; D000469:Alkaline Phosphatase; D011118:Polynucleotide Ligases