Structure of CheY

The binding interfaces on CheY for FliM and CheZ, which are localized to the C-terminal regions of CheY, overlap [489, 622, 655, 825]. Therefore, CheY cannot be bound simultaneously to both FliM and CheZ, for which reason CheZ can exert its phosphatase activity on CheY P only when the latter is not bound to the switch [134]. Furthermore, the C-terminal regions of CheY that interact with CheZ and FHM also overlap with the binding interface for CheA [654, 717, 825]. This suggests that, when bound to CheA, CheY cannot bind to CheZ or FliM. 

CheY apparently belongs to a superfamily of structurally similar proteins in prokaryotes [38, 755]. In addition, it has a significant sequence homology and three-dimensional structural similarity to the eukaryotic CTP-binding protein Ras p21 [152], as well as a three-dimensional structural resemblance to the superfamily of hydrolases, which consists of P-type ATPases, phosphatases, and more [601]. 

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Figure 12. CheY (PDB file 1CHN). (a) Immediate surroundings of the magnesium ion in the crystal structure of CheY. Note the magnesium-water-carboxylate motif of Figure 7 occurs twice in this magnesium coordination octahedron, (b) Further details of the active site of CheY.

Figure 20. Ribbon diagram of the 3-D structure of CheY. The diagram shows conserved residues that form the active site for phosphoryi transfer, inciuding the site for phosphorylation, Asp-57, and a catalytically essential Mg + (magenta sphere]. Gray and red spheres represent carbon and oxygen atoms, respectively. (Taken with permission from Djordjevic and Stock [192].)...

Zhu, X.Y., Rebello, J., Matsumura, P. and Volz, K. (1997). Crystal structures of CheY mutants Y106W and T87I/Y106W CheY activation correlates with movement of residue 106. J. Biol. Chem. 272, 5000-5006. 

Welch, M. Chinardet, N. Mourey, L. Birck, C. Samama, J.R Structure of the CheY-binding domain of histidine kinase CheA in complex with CheY. Nat. Struct. Biol., 5, 25-29 (1998)... 

In the absence of 02 the E. coli FNR protein induces proteins of the anaerobic respiration pathways. Nitrate also has its own two-component system that senses nitrate availability and activates transcription of enzymes catalyzing nitrate respiration.162 An expanded two-component system induces sporulation in Bacillus subtilis in response to poor growth conditions.163164 The crystal structure of one of two response regulators (SpoOF) has a structure closely related to that of CheY and the nitrate response regulator NarL. 

Figure 16. Schematic presentation of the structure of dimeric CheA. PI and P2 are the phosphotransfer and CheY-binding (or CheB-binding] domains, respectively. The phosphorylation site is in the PI domain. The ATP-binding site is in the kinase domain. CheW binds to the regulatory domain. Cylinders represent a-helices. (Taken with slight modifications and with permission from Stock [702].)...

The three-dimensional structure of the E. coli CheZ dimer in complex with the active analog of CheY, CheY-BeFs", has recently been revealed [812]. CheZ is a long four-helix bundle composed of two... 

Figure 21. Ribbon diagram of the 3-D structure of the complex between dimeric CheZ and CheY-BeFa" [(CheY-BeFa -Mg +JaCheZa]. The CheZa chains are cyan and orange and the CheY molecules are gray. BeFa (green) and Mg + (red) are in spacefilling representation. (Taken with permission from Zhao et at. [812].)...

A long-standing question in bacterial chemotaxis was whether CheZ is a specific phosphatase of CheY P or whether it is an allosteric regulator of the intrinsic dephosphorylation activity of CheY P. The structure of the CheZ CheY-BeF3 complex suggests that none of these mechanisms functions exclusively. Rather, the mechanism appears to... 

Chen, J.M., Lee, G., Murphy, R.B., Rrandt-Rauf, P. and Pincus, M.R. (1990). Comparisons between the three-dimensional structures of the chemotactic protein CheY and the normal Gly 12-p21 protein. Int. J. Peptide Protein Res. 36, 1-6. 

Hallddes, C.J., McEvoy, M.M., Casper, E., Matsumura, R, Volz, K. and Dahlquist, F.W. (2000). The 1.9 A resolution crystal structure of phosphono-CheY, an analogue of the active form of the response regulator, CheY. Biochemistry 39, 5280-5286. 

McEvoy, M.M. Muhandiram, D.R. Kay, L.E. Dahlquist, F.W. Structure and dynamics of a CheY-binding domain of the chemotaxis kinase CheA determined by nuclear magnetic resonance spectroscopy. Biochemistry, 35, 5633-5640 (1996)... 

Rice, M.S. and Dahlquist, F.W. (1991). Sites of deamidation and methylation in Tsr, a bacterial chemotaxis sensory transducer. J. Biol. Chem. 266, 9746-9753. Bidder, l.S. and Dijkstra, B.W. (1999). Identification of the Mg -binding site in the P-type ATPase and phosphatase members of the HAD (haloacid dehaloge-nase) superfamily by structural similarity to the response regulator protein CheY. Biochem. J. 339, 223-226. 

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