ENHANCEMENT OF DAMAGE-SPECIFIC DNA-BINDING OF XPA BY INTERACTION WITHTHE ERCC1 DNA-REPAIR PROTEIN

The human XPA and ERCC1 proteins, which are involved in early steps of nucleotide excision repair of DNA, specifically interacted in an in v itro binding assay and a yeast two-hybrid assay. A stretch of consecut ive glutamic acid residues in XPA was needed for binding to ERCC1. Bin ding of XPA to damaged DNA was markedly increased by the interaction o f the XPA and ERCC1 proteins. ERCC1 did not enhance binding to DNA whe n a truncated XPA protein, MF122, was used in place of the XPA protein . MF122 retains damaged DNA binding activity but lacks the region for protein-protein interaction including the E-cluster region. These resu lts suggest that the XPA/ERCC1 interaction may participate in damage-r ecognition as well as in incision at the 5' site of damage during nucl eotide excision repair. (C) 1995 Academic Press. Inc.