Excision Repair in Man and the Molecular Basis of Xeroderma Pigmentosum Syndrome

Abstract

Nucleotide excision repair is the removal of damaged nucleotides by incision of the damaged strand of a DNA duplex on both sides of the modified base(s) and release of an oligonucleotide carrying the lesion, followed by filling in of the single-stranded gap and ligation (Sancar and Sancar 1988). Although three proteins, UvrA, UvrB, and UvrC, are necessary and sufficient for carrying out the repair reaction proper (excision) in Escherichia coli (Sancar and Rupp 1983), genetic analyses suggest that in Saccharomyces cerevisiae and humans, at least eight genes may be necessary for the excision step (Hoeijmakers 1991). Considering that excision is a relatively simple reaction that involves damage recognition and two nucleophilic attacks on the DNA backbone, it may be asked whether all eight gene products are required for the excision reaction itself or if some of these proteins carry out functions necessary for excision but do not directly participate in...