Abstract
λ genes O and P are required for replication initiation from the bacteriophage λ origin site, oriλ, located within gene O. Questions have persisted for years about whether O-defects can indeed be complemented in trans. We show the effect of original null mutations in O and the influence of four origin mutations (three are in-frame deletions and one is a point mutation) on complementation. This is the first demonstration that O proteins with internal deletions can complement for O activity, and that expression of the N-terminal portion of gene P can completely prevent O complementation. We show that O-P co-expression can limit the lethal effect of P on cell growth. We explore the influence of the contiguous small RNA OOP on O complementation and P-lethality.
Highlights
Bacteriophage λ prophage is maintained within the chromosome of Escherichia coli cells by its CI repressor protein, which prevents the transcription of λ genes positioned leftward and rightward from promoters pL and pR that straddle cI (Figure 1A)
Upon inactivation of CI, the derepressed prophage genes N-int are expressed from pL, and genes cro-cII-O-P-Q are expressed from pR
The mechanism for bi-directional initiation of λ DNA replication involves a complex interaction of phage proteins gpO and gpP with E. coli host DNA replication proteins
Summary
Bacteriophage λ prophage is maintained within the chromosome of Escherichia coli cells by its CI repressor protein, which prevents the transcription of λ genes positioned leftward and rightward from promoters pL and pR that straddle cI (Figure 1A). Transcription initiated from pR requires gpN activity to proceed effectively past the rho-dependent tR1 termination site positioned between cro and cII (reviewed in [1,2,3,4]). The mechanism for bi-directional initiation of λ DNA replication involves a complex interaction of phage proteins gpO and gpP (designated as O and P) with E. coli host DNA replication proteins. Since the interaction of P with DnaB inactivates the helicase activity of DnaB, the dissociation of P bound to DnaB in the preprimosomal complex is required to restore DnaB activity, which involves E. coli heat shock proteins
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
