Figure 10.

Model of regulatory cascade of the expression of CsrA during the biphasic life cycle of L. pneumophila. (A) During the replicative phase, the transcription of csrA increases due to the degradation of the transcription inhibitor IHFB via ClpP, while the CsrA protein is avoided to be degraded by ClpP via an unknown mechanism, resulting in the accumulation of CsrA. (B) During the transmissive phase, IHFB binds to inhibit the transcription of csrA, while the accumulated CsrA is degraded by ClpP, leading to the decrease of intracellular CsrA. See text for details.