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Publication Abstract from PubMed

Pathogens often rely on thermosensing to adjust virulence gene expression. In yersiniae, important virulence-associated traits are under the control of the master regulator RovA which uses an in-built thermosensor to control its activity. Thermal upshifts encountered upon host entry induce conformational changes of the RovA dimer that attenuate DNA-binding and render the protein more susceptible to proteolysis. Here, we report the crystal structure of RovA in the free and DNA-bound form and provide evidence that thermo-induced loss of RovA activity is mainly promoted by a thermosensing loop in the dimerization domain and residues in the adjacent C-terminal helix. These determinants allow partial unfolding of the regulator upon an upshift to 37 degrees C. This structural distortion is transmitted to the flexible DNA-binding domain of RovA. RovA mainly contacts the DNA backbone in a low affinity-binding mode which allows the immediate release of RovA from its operator sites. We also show that SlyA, a close homologue of RovA from Salmonella with a very similar structure, is not a thermosensor and remains active and stable at 37 degrees C. Strikingly, changes in only three amino acids, reflecting evolutionary replacements in SlyA, result in a complete loss of the thermosensing properties of RovA and prevent degradation. In conclusion, only minor alterations can transform a thermotolerant regulator into a thermosensor that allows adjustment of virulence and fitness determinants to their thermal environment.

Structural basis for intrinsic thermosensing by the master virulence regulator RovA of Yersinia.,Quade N, Mendonca C, Herbst K, Heroven AK, Ritter C, Heinz DW, Dersch P J Biol Chem. 2012 Aug 30. PMID:22936808^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.