Repair of DNA-polypeptide crosslinks by human excision nuclease.
DNA-protein crosslinks are relatively common DNA lesions that form during the physiological processing of DNA by replication and recombination proteins, by side reactions of base excision repair enzymes, and by cellular exposure to bifunctional DNA-damaging agents such as platinum compounds. The mechanism by which pathological DNA-protein crosslinks are repaired in humans is not known. In this study, we investigated the mechanism of recognition and repair of protein-DNA and oligopeptide-DNA crosslinks by the human excision nuclease. Under our assay conditions, the human nucleotide excision repair system did not remove a 16-kDa protein crosslinked to DNA at a detectable level. However, 4- and 12-aa-long oligopeptides crosslinked to the DNA backbone were recognized by some of the damage recognition factors of the human excision nuclease with moderate selectivity and were excised from DNA at relatively efficient rates. Our data suggest that, if coupled with proteolytic degradation of the crosslinked protein, the human excision nuclease may be the major enzyme system for eliminating protein-DNA crosslinks from the genome.
Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA.
Joyce T
JT
Reardon
Aziz
A
Sancar
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D006224:Cricetinae; D003432:Cross-Linking Reagents; D004247:DNA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair / Q000502:physiology*; D045643:DNA Repair Enzymes / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008954:Models, Biological; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D021122:Protein Subunits; D013379:Substrate Specificity; D051760:Xeroderma Pigmentosum Group A Protein / Q000737:chemistry / Q000378:metabolism
D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D010455:Peptides; D021122:Protein Subunits; C497314:XPA protein, human; D051760:Xeroderma Pigmentosum Group A Protein; C086984:XPC protein, human; D004247:DNA; D045643:DNA Repair Enzymes