BvgS of Pathogenic Bordetellae: a Paradigm for Sensor-kinases with Venus Flytrap Perception Domains
Françoise Jacob-Dubuisson, René Wintjens, Julien Herrou, Elian Dupré and Rudy Antoine
from: Two-Component Systems in Bacteria (Edited by: Roy Gross and Dagmar Beier). Caister Academic Press, U.K. (2012)
The whooping cough agent Bordetella pertussis regulates the expression of its virulence regulon through the two-component system BvgAS. BvgA is a canonical response regulator serving as a transcriptional activator when phosphorylated. BvgS is a multidomain, hybrid sensor-kinase harbouring several cytoplasmic domains that mediate a complex phospho-transfer cascade. BvgS also contains two periplasmic Venus flytrap (VFT) domains in tandem. It is thus the prototype for a large family of bacterial VFT-containing sensor-kinases, whose molecular mechanisms for signal perception and transduction remain to be deciphered. Ubiquitous in nature, VFT domains usually function along a clamshell model, with two lobes that enclose specific ligands. Structure/function analyses of the second VFT domain of BvgS have indicated a non-canonical behaviour, whereby this domain adopts a closed conformation that gives a positive signal to the system in the absence of a bona fide ligand and can also bind negative signals that turn off the system. Sequence analyses of BvgS have shown a strong conservation of the region linking the periplasmic and cytoplasmic domains, indicating that it is essential for signal transduction. On the contrary, the linkers between VFT domains are not conserved, and thus the VFT most likely communicate with each other via their interfaces read more ...