Jiang, Meiying and Bourret, Robert B. and Sinsheimer, Melvin I. and Volz, Karl (1997) Uncoupled Phosphorylation and Activation in Bacterial Chemotaxis - The 2.3 Å structure of an aspartate to lysine mutant at position 13 of CheY. Journal of Biological Chemistry, 272 (18). pp. 11850-11855. ISSN 0021-9258 http://resolver.caltech.edu/CaltechAUTHORS:JIAjbc97
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An aspartate to lysine mutation at position 13 of the chemotaxis regulatory protein CheY causes a constitutive tumbly phenotype when expressed at high copy number in vivo even though the mutant protein is not phosphorylatable. These properties suggest that the D13K mutant adopts the active, signaling conformation of CheY independent of phosphorylation, so knowledge of its structure could explain the activation mechanism of CheY. The x-ray crystallographic structure of the CheY D13K mutant has been solved and refined at 2.3 Å resolution to an R-factor of 14.3%. The mutant molecule shows no significant differences in backbone conformation when compared with the wild-type, Mg2+-free structure, but there are localized changes within the active site. The side chain of lysine 13 blocks access to the active site, whereas its epsilon -amino group has no bonding interactions with other groups in the region. Also in the active site, the bond between lysine 109 and aspartate 57 is weakened, and the solvent structure is perturbed. Although the D13K mutant has the inactive conformation in the crystalline form, rearrangements in the active site appear to weaken the overall structure of that region, potentially creating a metastable state of the molecule. If a conformational change is required for signaling by CheY D13K, then it most likely proceeds dynamically, in solution.
|Additional Information:||©1997 by The American Society for Biochemistry and Molecular Biology, Inc. (Received for publication, December 18, 1996) We thank E. Westbrook and M. Westbrook for help and generosity in data collection at Argonne National Laboratory. This work was supported by National Institutes of Health Grants GM39919 and GM47522 (to K.V.) and AI19296 (to M.I.S.) and by a National Research Service Award Fellowship AI07798 (to R.B.B.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. The atomic coordinates and structure factors (code pdb1ehc.ent and r1ehc.ss) have been deposited in the Protein Data Bank, Brookhaven National Laboratory, Upton, NY.|
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|Deposited On:||15 Mar 2007|
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