NMR structure of activated CheY

The CheY protein is the response regulator in bacterial chemotaxis. Phospho rylation of a conserved aspartyl residue induces structural changes that co nvert the protein from an inactive to an active state. The short half-life of the aspartyl-phosphate has precluded detailed structural analysis of the active protein. Persistent activation of Escherichia coli CheY was achieve d by complexation with beryllofluoride (BeF3-) and the structure determined by NMR spectroscopy to a backbone r.m.s.d. of 0.58(+/-0.08) Angstrom. Form ation of a hydrogen bond between the Thr87 OH group and an active site acce ptor, presumably Asp57.BeF3-, stabilizes a coupled rearrangement of highly conserved residues, Thr87 and Tyr106, along with displacement of beta 4 and H4, to yield the active state. The coupled rearrangement may be a more gen eral mechanism for activation of receiver domains. (C) 2000 Academic Press.