Bacteriophage λ development: temporal switches and the choice of lysis or lysogeny

Bacteriophage λ executes a regulated temporal program along two pathways, lytic or lysogenic. Each pathway depends on controlled, sequential synthesis and subsequent activity of λ-encoded proteins. The choice of pathway requires an initial partition specified by the relative activity of the λ cII regulatory protein, followed by a stabilization of this choice by other λ proteins. The stabilization events involve competition by the repressors cI and Cro for control of developmental transcription and by the recombination proteins Int and Xis for the direction of site-specific recombination. Several host and phage proteins exert post-transcriptional control on the amount of cII, presumably transducing physiological signals for choice of pathway.