Role of the PFXFATG[G/Y] Motif in the Activation of SdrG, a Response Regulator Involved in the Alphaproteobacterial General Stress Response.
Campagne, S., Dintner, S., Gottschlich, L., Thibault, M., Bortfeld-Miller, M., Kaczmarczyk, A., Francez-Charlot, A., Allain, F.H., Vorholt, J.A.(2016) Structure 24: 1237-1247
- PubMed: 27396826 
- DOI: https://doi.org/10.1016/j.str.2016.05.015
- Primary Citation of Related Structures:  
5IEB, 5IEJ - PubMed Abstract: 
Two-component systems are major signal transduction pathways, which consist of histidine kinases and response regulators that communicate through phosphorylation. Here, we highlight a distinct class of single-domain response regulators containing the PFXFATG[G/Y] motif that are activated by a mechanism distinct from the Y-T coupling described for prototypical receiver domains. We first solved the structures of inactive and active SdrG, a representative of the FAT GUY family, and then biochemically and genetically characterized variants in which residues in this motif were mutated. Our results support a model of activation mainly driven by a conserved lysine and reveal that the rotation of the threonine induces the reorganization of several aromatic residues in and around the PFXFATG[G/Y] motif to generate intermediates resembling those occurring during classical Y-T coupling. Overall, this helps define a new subfamily of response regulators that emerge as important players in physiological adaptation.
Organizational Affiliation: 
Institute of Microbiology, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland; Institute of Molecular Biology and Biophysics, ETH Zurich, Hönggerbergring 64, 8093 Zürich, Switzerland. Electronic address: sebastien.campagne@mol.biol.ethz.ch.