title: Bacteriophage lambda replication proteins: formation of a mixed oligomer and binding to the origin of lambda DNA.
abstract: The purified bacteriophage lambda replication proteins O and P sediment separately in metrizamide gradients of low ionic strength as dimers. Together they interact with each other forming an oligomer, composed of two molecules of lambda O and one molecule of lambda P. The lambda O-P oligomer is active in the in vitro replication of ori lambda-containing DNA. Equilibrium sedimentation in preformed metrizamide density gradients under conditions that separate DNA-protein complexes from free proteins was employed in order to study possible interactions among the lambda replication proteins and ori lambda DNA. It was found that the lambda P protein binds specifically to ori lambda-containing plasmid DNA only in the presence of lambda O protein. About 100 molecules of lambda O and 10 molecules of lambda P form a complex with the ori lambda DNA. The lambda DNA-lambda O-lambda P complex was shown to be active in an in vitro replication system. Since the physical interactions between ori lambda and lambda O and between lambda P and the Escherichia coli dnaB replication protein are well documented, the evidence for a lambda O-P interaction presented in this paper provides the missing link in the molecular mechanism that enables lambda to direct the host replication machinery to the replication of its own DNA.
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics*; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D008970:Molecular Weight; D010957:Plasmids; D014764:Viral Proteins / Q000235:genetics* / Q000302:isolation & purification; D014779:Virus Replication
chemical_list: C024013:DNA replication complex protein, Bacteriophage lambda; D004279:DNA, Viral; D014764:Viral Proteins