Structure of the Constitutively Active Double Mutant CheY[superscript D13K Y106W] Alone and in Complex with a FliM Peptide
- MBC
CheY is a member of the response regulator protein superfamily that controls the chemotactic swimming response of motile bacteria. The CheY double mutant D13K Y106W (CheY**) is resistant to phosphorylation, yet is a highly effective mimic of phosphorylated CheY in vivo and in vitro. The conformational attributes of this protein that enable it to signal in a phosphorylation-independent manner are unknown. We have solved the crystal structure of selenomethionine-substituted CheY** in the presence of its target, a peptide (FliM{sub 16}) derived from the flagellar motor switch, FliM, to 1.5 {angstrom} resolution with an R-factor of 19.6%. The asymmetric unit contains four CheY** molecules, two with FliM{sub 16} bound, and two without. The two CheY** molecules in the asymmetric unit that are bound to FliM{sub 16} adopt a conformation similar to BeF{sub 3}{sup -}-activated wild-type CheY, and also bind FliM{sub 16} in a nearly identical manner. The CheY** molecules that do not bind FliM{sub 16} are found in a conformation similar to unphosphorylated wild-type CheY, suggesting that the active phenotype of this mutant is enabled by a facile interconversion between the active and inactive conformations. Finally, we propose a ligand-binding model for CheY and CheY**, in which Ile95 changes conformation in a Tyr/Trp106-dependent manner to accommodate FliM.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1008713
- Journal Information:
- J. Mol. Biol., Vol. 342, Issue (4) ; 09, 2004; ISSN 0022-2836
- Country of Publication:
- United States
- Language:
- ENGLISH
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