Fig. 5.

Model of cell-cycle acceleration upon surface contact. Surface sensing through alterations in pilus retraction upon surface binding stimulates the switch in PleC activity from phosphatase to kinase, concomitant with its delocalization from the piliated pole. This in turn stimulates the localization of SpmX, which recruits the kinase DivJ. DivJ phosphorylates PleD and DivK, resulting in the production of c-di-GMP and the stimulation of DNA replication, respectively. Increased c-di-GMP production from phosphorylated PleD results in more holdfast synthesis and stalk growth.