Phage Lambda P protein: trans-activation, inhibition phenotypes and their suppression

• Published in: Viruses 2013-02, Vol.5 (2), p.619-653
• Main Authors: Hayes, Sidney, Erker, Craig, Horbay, Monique A, Marciniuk, Kristen, Wang, Wen, Hayes, Connie
• Format: Article
• Language: English
• Subjects: Alleles; allelic alterations of dnaB and P; bacteriophage lambda (λ) replication initiation protein P; Bacteriophage lambda - genetics; Bacteriophage lambda - growth & development; Bacteriophage lambda - metabolism; cellular filamentation; ColE1 plasmid curing and replication inhibition; DNA Replication; E coli; E. coli DnaB replicative helicase; Escherichia coli - genetics; Escherichia coli - metabolism; Gene Expression; Gene Order; Genes; Genes, Lethal; Genetic Complementation Test; Hypotheses; Mutation; Phenotype; Plasmids; Plasmids - genetics; Proteins; SOS Response (Genetics); Temperature; Trans-Activators - genetics; Trans-Activators - immunology; Trans-Activators - metabolism; Transformation, Bacterial; Viral Proteins - genetics; Viral Proteins - immunology; Viral Proteins - metabolism; Virus Replication
• ISSN: 1999-4915; 1999-4915
• DOI: 10.3390/v5020619

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.