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Figure 6 | BMC Systems Biology

Figure 6

From: A predictive computational model of the kinetic mechanism of stimulus-induced transducer methylation and feedback regulation through CheY in archaeal phototaxis and chemotaxis

Figure 6

Overview of mechanisms and interactions between components in the final Model 6. The same colors as in Figure 1 are used for identical proteins in (A) and (B). For short notation the prefix "Che" is omitted. Activating and inactivating signaling states are shaded in red and green, respectively. Model components and interactions in (A) and (B): (1) R-TWA complex; (2) diffusive response regulator CheY/CheYp; (3) reversible transducer methylation by CheB and CheR; (4) R-TWA units of different transducer/receptor types; the active conformation (corresponding to phosphorylated CheA) of the R-TWA complex (1) enhances the phosphate transfer (a) to CheY; signals of all R-TWA complexes are integrated (d) by CheY phosphorylation; CheY binds (c) to the R-TWA complexes and globally coordinates reversible transducer methylation (e); each R-TWA signaling unit (4) consists of several (here three) R-TWA complexes of different receptors/transducers. CheYp binds to the motor and increases switching probability. (C) SRI is the sensor for orange and near-uv light, SRII senses blue light. Photon absorption produces a sequence of intermediate photoproducts where the long-lived photointermediates are signaling states. Other, short-lived photointermediates are not shown. (D) Regulation of antagonistic reversible transducer demethylation/methylation by bound CheY and by complex activity during the adaptation process. Notation: , unmethylated/methylated activating site; , unmethylated/methylated inactivating site. Upon a saturating repellent (increase of activity A and no unbound CheY) transducer modification is shifted towards demethylation of the activating site () which brings the system back into an adapted state.

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