The Rcs (regulator of capsule synthesis) signalling complex comprises the membrane-associated hybrid sensor kinases RcsC and RcsD, the transcriptional regulator RcsB and the two co-inducers RcsA and RcsF. Acting as a global regulatory network, the Rcs phosphorelay controls multiple cellular pathways including capsule synthesis, cell division, motility, biofilm formation and virulence mechanisms. Signal-dependent communication of the individual Rcs domains showing histidine kinase, phosphoreceiver, phosphoryl transfer and DNA-binding activities is characteristic and essential for the modulation of signal transfer. We have analysed the structures of core elements of the Rcs network including the RcsC-PR (phosphoreceiver domain of RcsC) and the RcsD-HPt (histidine phosphotransfer domain of RcsD), and we have started to characterize the dynamics and recognition mechanisms of the proteins. RcsC-PR represents a typical CheY-like α/β/α sandwich fold and it shows a large conformational flexibility near the active-site residue Asp875. NMR analysis revealed that RcsC-PR is able to adopt preferred conformations upon Mg2+ co-ordination, BeF3− activation, phosphate binding and RcsD-HPt recognition. In contrast, the α-helical structure of RcsD-HPt is conformationally stable and contains a recognition area in close vicinity to the active-site His842 residue. Our studies indicate the importance of protein dynamics and conformational exchange for the differential response to the variety of signals perceived by complex regulatory networks.
Modulation of the Rcs-mediated signal transfer by conformational flexibility
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Vladimir V. Rogov, Kerstin Schmöe, Fank Löhr, Natalia Yu. Rogova, Frank Bernhard, Volker Dötsch; Modulation of the Rcs-mediated signal transfer by conformational flexibility. Biochem Soc Trans 1 December 2008; 36 (6): 1427–1432. doi: https://doi.org/10.1042/BST0361427
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