SPECIES-SPECIFIC FUNCTIONAL INTERACTIONS OF DNA-POLYMERASE ALPHA-PRIMASE WITH SIMIAN-VIRUS-40 (SV40) T-ANTIGEN REQUIRE SV40 ORIGIN DNA

Physical and functional interactions of simian virus 40 (SV40) and pol yomavirus large-T antigens with DNA polymerase alpha-primase were anal yzed to elucidate the molecular basis for the species specificity of p olymerase alpha-primase in viral DNA replication. SV40 T antigen assoc iated more efficiently with polymerase alpha-primase in crude human ex tracts than in mouse extracts, while polyomavirus T antigen interacted preferentially with polymerase alpha-primase in mouse extracts. The a pparent species specificity of complex formation was not observed when purified polymerase alpha-primases were substituted for the crude ext racts. Several functional interactions between T antigen and purified polymerase alpha-primase, including stimulation of primer synthesis an d primer elongation on M13 DNA in the presence or absence of the singl e-stranded DNA binding protein RP-A, also proved to be independent of the species from which polymerase alpha-primase had been purified. How ever, the human DNA polymerase alpha-primase was specifically required for primosome assembly and primer synthesis on SV40 origin DNA in the presence of T antigen and RP-A.