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Phage Lambda P Protein: Trans-Activation, Inhibition Phenotypes and their Suppression
Department of Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, S7N 5E5, Canada
* Author to whom correspondence should be addressed.
Received: 4 December 2012; in revised form: 21 January 2013 / Accepted: 29 January 2013 / Published: 6 February 2013
Abstract: The initiation of bacteriophage λ replication depends upon interactions between the oriλ DNA site, phage proteins O and P, and E. coli host replication proteins. P exhibits a high affinity for DnaB, the major replicative helicase for unwinding double stranded DNA. The concept of P-lethality relates to the hypothesis that P can sequester DnaB and in turn prevent cellular replication initiation from oriC. Alternatively, it was suggested that P-lethality does not involve an interaction between P and DnaB, but is targeted to DnaA. P-lethality is assessed by examining host cells for transformation by ColE1-type plasmids that can express P, and the absence of transformants is attributed to a lethal effect of P expression. The plasmid we employed enabled conditional expression of P, where under permissive conditions, cells were efficiently transformed. We observed that ColE1 replication and plasmid establishment upon transformation is extremely sensitive to P, and distinguish this effect from P-lethality directed to cells. We show that alleles of dnaB protect the variant cells from P expression. P-dependent cellular filamentation arose in ΔrecA or lexA[Ind-] cells, defective for SOS induction. Replication propagation and restart could represent additional targets for P interference of E. coli replication, beyond the oriC-dependent initiation step.
Keywords: E. coli DnaB replicative helicase; bacteriophage lambda (λ) replication initiation protein P; allelic alterations of dnaB and P; ColE1 plasmid curing and replication inhibition; cellular filamentation
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Hayes, S.; Erker, C.; Horbay, M.A.; Marciniuk, K.; Wang, W.; Hayes, C. Phage Lambda P Protein: Trans-Activation, Inhibition Phenotypes and their Suppression. Viruses 2013, 5, 619-653.
Hayes S, Erker C, Horbay MA, Marciniuk K, Wang W, Hayes C. Phage Lambda P Protein: Trans-Activation, Inhibition Phenotypes and their Suppression. Viruses. 2013; 5(2):619-653.
Hayes, Sidney; Erker, Craig; Horbay, Monique A.; Marciniuk, Kristen; Wang, Wen; Hayes, Connie. 2013. "Phage Lambda P Protein: Trans-Activation, Inhibition Phenotypes and their Suppression." Viruses 5, no. 2: 619-653.