Segmental motions, not a two-state concerted switch, underlie allostery in CheY.
The switch between an inactive and active conformation is an important transition for signaling proteins, yet the mechanisms underlying such switches are not clearly understood. Escherichia coli CheY, a response regulator protein from the two-component signal transduction system that regulates bacterial chemotaxis, is an ideal protein for the study of allosteric mechanisms. By using 15N CPMG relaxation dispersion experiments, we monitored the inherent dynamic switching of unphosphorylated CheY. We show that CheY does not undergo a two-state concerted switch between the inactive and active conformations. Interestingly, partial saturation of Mg2+ enhances the intrinsic allosteric motions. Taken together with chemical shift perturbations, these data indicate that the μs-ms timescale motions underlying CheY allostery are segmental in nature. We propose an expanded allosteric network of residues, including W58, that undergo asynchronous, local switching between inactive and active-like conformations as the primary basis for the allosteric mechanism.
Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Leanna R
LR
McDonald
Joshua A
JA
Boyer
Andrew L
AL
Lee
D000465:Algorithms; D000494:Allosteric Regulation; D000495:Allosteric Site; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D020134:Catalytic Domain; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D006860:Hydrogen Bonding; D008274:Magnesium / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics; D000072236:Methyl-Accepting Chemotaxis Proteins; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D017433:Protein Structure, Secondary
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C000607606:cheY protein, E coli; D008274:Magnesium