Figure 3.

Proposed method of activation of the Rcs system via the outer membrane sensor RcsF. Left: Under non-inducing conditions, the lipoprotein RcsF is tethered to the outer membrane and threads through the lumen of β-barrel proteins (Cho et al. 2014; Konovalova et al. 2014) (the two studies reported opposite orientations of RcsF in the membrane). In this state, RcsF is unable to contact its inner membrane receptor IgaA, and can therefore not activate the Rcs system, i.e. the dephosphorylation activity of RcsC predominates. Right: By a yet unclear mechanism, envelope stress can interfere with the ability of periplasmic chaperones or BamA to localize RcsF to its regular location and thereby enables it to activate the Rcs system (Cho et al. 2014).