Refactoring the λ phage lytic/lysogenic decision with a synthetic regulator

In this work, we explore the refactoring of the circuitry of λ phage by engineering a new‐to‐nature regulator that responds to an ad hoc input signal that behaves orthogonal with respect to the host cell. We tailored a chimeric regulator, termed Qλ, between the CI protein of the λ phage and the BzdR repressor from Azoarcus sp. strain CIB that responds to benzoyl‐CoA. When the Qλ was expressed in the appropriate Escherichia coli cells, it was able to reprogram the lytic/lysogenic λ phage decision according to the intracellular production of benzoyl‐CoA. Our results are also an example of how generating new artificial regulators that respond to effectors of choice may be useful to control different cellular processes.