Figure 7
From: An iron detection system determines bacterial swarming initiation and biofilm formation
Proposed model for the control of swarming and biofilm formation by the RssAB-ICDH-Coumarin-iron pathway.
(a) Low extracellular Fe3+ deactivates RssAB signaling and relieves transcription of the pvc cluster and flhDC, which encodes the master regulator of flagellum biosynthesis This in turn increases flagellum and production of ICDH-Coumarin which subsequently chelates Fe3+ to maintain low availability of free Fe3+. These processes induce swarming and repress biofilm formation. (b) High extracellular Fe3+ activates RssAB signaling, leading to phosphorylation of RssB, repression of pvc cluster and flhDC transcription, and reduced ICDH-Coumarin and flagellum production. High Fe3+ availability sustains activation of RssAB signaling. These processes lead to biofilm formation and inhibit swarming migration by restraining bacteria in the swarming lag phase.
