FIG. 6.

Model of AinS regulation of the acetate switch in V. fischeri. AinS signaling, which regulates an unknown activity(ies) required for persistent colonization in the symbiosis (23), sits atop a phosphorelay cascade that ultimately leads to translation of the master regulator LitR. LitR, which controls luminescence and protease activity through LuxIR induction (1), also blocks motility, and it activates transcription of acs. By an independent route, LitR regulates an unknown gene(s) required for normal initiation of symbiosis (14). Solid lines indicate direct steps that have been demonstrated. Dotted lines indicate an unknown number of steps.