Functional studies on the interaction between human replication protein A and Xeroderma pigmentosum group A complementing protein (XPA)

The human replication protein A (RPA; also known as human single-stranded D NA binding protein, HSSB) is a multisubunit complex (70, 34 and 11 kDa subu nits) involved in the three processes of DNA metabolism; replication, repai r, recombination, We found that both 34 and 70 kDa subunits (p34 and p70, r espectively), of RPA interacts with the Xeroderma pigmentosum group A compl ementing protein (XPA), a protein that specifically recognizes UV-damaged D NA, Our mutational analysis indicated that no particular domains of RPA p70 were essential for its interaction with XPA, We also examined the effect o f this XPA-RPA interaction on in vitro simian virus 40 (SV40) DNA replicati on catalyzed by the crude extract and monopolymerase system. XPA inhibited SV40 DNA replication in vitro through its interaction with RPA, Taken toget her, these results suggest that there is a role for RPA in the regulation o f DNA metabolism through its ability to modulate the interactions of protei ns involved in the processes of DNA metabolism.