Prophage Induction of Phage λ
John W. Little
from: Bacteriophage: Genetics and Molecular Biology (Edited by: Stephen Mc Grath and Douwe van Sinderen). Caister Academic Press, U.K. (2007)
The gene regulatory circuitry of phage λ is among the best-understood circuits at the mechanistic level. This circuitry involves several interesting regulatory behaviors. An infected cell undergoes a decision between two alternative pathways, the lytic and lysogenic pathways. If the latter is followed, the lysogenic state is established and maintained. While this state is highly stable, it can switch to the lytic pathway in the process of prophage induction, which occurs when the host SOS response is triggered by DNA damage. We first review events that stabilize the lysogenic pathway and that affect the lysis-lysogeny decision. This is followed by a more extensive description of prophage induction. This process displays threshold behavior, and a model for this behavior is presented. Other aspects of systems behavior in the l circuitry are briefly described. Finally, we discuss insights into the evolution of complex regulatory circuits afforded by studies with the λ circuitry read more ...