P2 Growth Restriction on an rpoC Mutant Is Suppressed by Alleles of the Rz1 Homolog lysC

Abstract

ABSTRACT Escherichia coli strain 397c carries a temperature-sensitive mutation, rpoC397 , that removes the last 50 amino acids of the RNA polymerase β′ subunit and is nonpermissive for plating of bacteriophage P2. P2 gor mutants productively infect 397c and define a new gene, lysC , encoded by a reading frame that extensively overlaps the P2 lysis accessory gene, lysB . The unusual location of lysC with respect to lysB is reminiscent of the Rz/Rz1 lysis gene pair of phage λ. Indeed, coexpression of lysB and lysC complemented the growth defect of λ Rz / Rz1 null mutants, indicating that the LysB/C pair is similar to Rz/Rz1 in both gene arrangement and function. Cells carrying the rpoC397 mutation exhibited an early onset of P2-induced lysis, which was suppressed by the gor mutation in lysC . We propose that changes in host gene expression resulting from the rpoC397 mutation result in changes in the composition of the bacterial cell wall, making the cell more susceptible to P2-mediated lysis and preventing accumulation of progeny phage sufficient for plaque formation.