MSSP, a protein binding to an origin of replication in the c- myc gene, interacts with a catalytic subunit of DNA polymerase α and stimulates its polymerase activity

Abstract

MSSP has been identified as a protein that binds to both single- and double-stranded sequences of a putative DNA replication origin sequence in the human c- myc gene. MSSP possesses versatile functions, including stimulation of DNA replication, transcriptional regulation, apoptosis induction, and cell transformation coordinated by c-Myc. MSSP contains two RNP domains, RNP1-A and RNP1-B, both of which are necessary for all of the functions of MSSP. In this study, we found that MSSP binds to the N-terminal region of a catalytic subunit of a human DNA polymerase α via its RNP domains both in vitro and in human cells. Furthermore, MSSP was released from the putative DNA replication origin of the c- myc gene after it complexed with DNA polymerase α, and MSSP stimulated DNA polymerase activity in vitro.