In vitro strand exchange promoted by the herpes simplex virus type-1 single strand DNA-binding protein (ICP8) and DNA helicase-primase.
The genome of herpes simplex virus type-1 undergoes a high frequency of homologous recombination in the absence of a virus-encoded RecA-type protein. We hypothesized that viral homologous recombination is mediated by the combined action of the viral single strand DNA-binding protein (ICP8) and helicase-primase. Our results show that ICP8 catalyzes the formation of recombination intermediates (joint molecules) between circular single-stranded acceptor and linear duplex donor DNA. Joint molecules formed by invasion of a 3'-terminal strand displaces the non-complementary 5'-terminal strand, thereby creating a loading site for the helicase-primase. Helicase-primase acts on these joint molecules to promote ATP-dependent branch migration. Finally, we have reconstituted strand exchange by the synchronous action of ICP8 and helicase-primase. Based on these data, we present a recombination mechanism for a eukaryotic DNA virus in which a single strand DNA-binding protein and helicase cooperate to promote homologous pairing and branch migration.
Nimonkar
Amitabh V
AV
Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, Florida 33101-6129, USA.
Boehmer
Paul E
PE
D002384:Catalysis; D004265:DNA Helicases / Q000378:metabolism*; D019915:DNA Primase / Q000378:metabolism*; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis / Q000378:metabolism; D004268:DNA-Binding Proteins; D018259:Herpesvirus 1, Human / Q000378:metabolism*; D011995:Recombination, Genetic; D014764:Viral Proteins / Q000378:metabolism*
D004279:DNA, Viral; D004268:DNA-Binding Proteins; C045462:ICP8 protein, Simplexvirus; D014764:Viral Proteins; D019915:DNA Primase; D004265:DNA Helicases