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. Author manuscript; available in PMC: 2012 May 1.
Published in final edited form as: Mol Microbiol. 2011 Feb 24;80(3):596–611. doi: 10.1111/j.1365-2958.2011.07577.x

Fig. 5. Biphasic output diagram for Tsr-HAMP signaling.

Fig. 5

(A) The diagram summarizes the proposed relationship between HAMP or MH bundle stability and kinase activity or flagellar rotation pattern. This extended dynamic bundle model proposes two kinase-off signaling states, CCW(A) and CCW(B), at opposite extremes of the HAMP bundle stability range. Receptors with intermediate stabilities activate the CheA kinase to produce CW output signals. Wild-type Tsr molecules normally operate in the high HAMP/low MH stability regime, where kinase activity increases monotonically with HAMP instability (or MH bundle stability). The precise shape of the output curve is arbitrary. Wild-type Tsr molecules in the QEQE modification state (i.e., in adaptation-deficient strains) exhibit ~75% CW output (dark gray circle), which is reduced to ~25% CW output in adaptation-proficient strains (the adaptation set-point). Filled arrowheads denote structure stabilizing influences; open arrowheads denote structure destabilizing influences. Attractant and repellent stimuli directly influence HAMP bundle stability; CheR and CheB modifications directly modulate MH bundle stability.

(B) Rotation patterns produced by Tsr wild-type molecules in various strains. The rotation data are averages and standard deviations for at least three experiments (see Table S1).