Regulation of the Anti-termination RNA Transcription Complex by Lon-Mediated Lambda N Degradation.

The lambda N protein (λN) is an intrinsically unstructured protein functioning to mediate anti-termination transcription of lambda phage RNA during the infection of Escherichia coli (E. coli) host by interacting with the host's macromolecular transcription machinery. In E. coli host, λN is primarily turned over by the ATP-dependent protease Lon. While it has been demonstrated that Escherichia coli Lon (ELon) readily degrades purified λN in vitro, it is unclear how ELon degrades λN in the RNA anti-termination transcription complex. The N-dependent anti-termination transcription mechanism of Escherichia coli RNA polymerase (ERNAP) and the quality control functions of Lon have been extensively studied and reviewed in literature. By contrast, very little is known about Lon's function as a regulatory protease. Herein, we provide a survey of literature and newfound evidence showing how ELon regulates anti-termination RNA transcription assemblies by using λN as a substrate. Elucidating how a substrate interacts with the various components in the assembly (ERNAP versus ELon) can dictate whether anti-termination transcription or degradation occurs.