Summary
The purified bacteriophage λ 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 λO and one molecule of λP. The λO-P oligomer is active in the in vitro replication of oriλ-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 λ replication proteins and oriλ DNA. It was found that the λP protein binds specifically to oriλ-containing plasmid DNA only in the presence of λO protein. About 100 molecules of λO and 10 molecules of λP form a complex with the oriλ DNA. The λ DNA-λO-λP complex was shown to be active in an in vitro replication system.
Since the physical interactions between oriλ and λO and between λP and the Escherichia coli dnaB replication protein are well documented, the evidence for a λO-P interaction presented in this paper provides the missing link in the molecular mechanism that enables λ to direct the host replication machinery to the replication of its own DNA.
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Communicated by W. Gajewski
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Zylicz, M., Gorska, I., Taylor, K. et al. Bacteriophage λ replication proteins: Formation of a mixed oligomer and binding to the origin of λ DNA. Molec. Gen. Genet. 196, 401–406 (1984). https://doi.org/10.1007/BF00436186
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DOI: https://doi.org/10.1007/BF00436186