Pathways & interactions
Signal transduction response regulator, predicted, VieB (IPR014460)
Short name: Sig_transdc_resp-reg_VieB
Overlapping homologous superfamilies
Two-component signal transduction systems enable bacteria to sense, respond, and adapt to a wide range of environments, stressors, and growth conditions [PMID: 16176121]. Some bacteria can contain up to as many as 200 two-component systems that need tight regulation to prevent unwanted cross-talk [PMID: 18076326]. These pathways have been adapted to response to a wide variety of stimuli, including nutrients, cellular redox state, changes in osmolarity, quorum signals, antibiotics, and more [PMID: 12372152]. Two-component systems are comprised of a sensor histidine kinase (HK) and its cognate response regulator (RR) [PMID: 10966457]. The HK catalyses its own auto-phosphorylation followed by the transfer of the phosphoryl group to the receiver domain on RR; phosphorylation of the RR usually activates an attached output domain, which can then effect changes in cellular physiology, often by regulating gene expression. Some HK are bifunctional, catalysing both the phosphorylation and dephosphorylation of their cognate RR. The input stimuli can regulate either the kinase or phosphatase activity of the bifunctional HK.
A variant of the two-component system is the phospho-relay system. Here a hybrid HK auto-phosphorylates and then transfers the phosphoryl group to an internal receiver domain, rather than to a separate RR protein. The phosphoryl group is then shuttled to histidine phosphotransferase (HPT) and subsequently to a terminal RR, which can evoke the desired response [PMID: 11934609, PMID: 11489844].
Response regulators of the microbial two-component signal transduction systems typically consist of an N-terminal CheY-like receiver (phosphoacceptor) domain and a C-terminal output (usually DNA-binding) domain. In response to an environmental stimulus, a phosphoryl group is transferred from the His residue of sensor histidine kinase to an Asp residue in the CheY-like receiver domain of the cognate response regulator [PMID: 10966457, PMID: 10500846, PMID: 11406410]. Phosphorylation of the receiver domain induces conformational changes that activate an associated output domain, which in turn triggers the response. Phosphorylation-induced conformational changes in response regulator molecules have been demonstrated in direct structural studies [PMID: 10622255].
The output domain found in this group is so far unique. In part, it contains a divergent version of TPR repeats.
- PIRSF011521 (VieB)