AUTOGRAPHA-CALIFORNICA NUCLEAR POLYHEDROSIS-VIRUS P143 GENE-PRODUCT IS A DNA-BINDING PROTEIN

We have identified the protein product of the Autographa californica n uclear polyhedrosis virus (AcMNPV) p143 gene by constructing a recombi nant baculovirus overexpressing the gene product P143. The overexpress ed protein exhibited a relative mobility of approximately 140 kDa and was stable for at least 12 hr after synthesis. Immunoblotting using a monoclonal antibody developed against the overexpressed protein identi fied a similar polypeptide in AcMNPV-infected cells which was detectab le by 4 hr postinfection. P143 was present within infected cell nuclei at relatively constant amounts until at least 72 hr after infection, suggesting that P143 may perform other functions at late times after i nfection. P143, purified from infected cell nuclei by chromatography o ver hydroxylapatite and DNA cellulose, bound in a sequence-independent fashion to double-stranded but not to single-stranded DNA to form a l adder of retarded protein-DNA complexes. Together, these data are cons istent with the essential role of P143 for viral DNA replication and s uggest that P143 may function by direct binding to DNA. (C) 1997 Acade mic Press.