PMID:15994328
| Citation |
Quezada, CM, Hamel, DJ, Gradinaru, C, Bilwes, AM, Dahlquist, FW, Crane, BR and Simon, MI (2005) Structural and chemical requirements for histidine phosphorylation by the chemotaxis kinase CheA. J. Biol. Chem. 280:30581-5 |
|---|---|
| Abstract |
The CheA histidine kinase initiates the signal transduction pathway of bacterial chemotaxis by autophosphorylating a conserved histidine on its phosphotransferase domain (P1). Site-directed mutations of neighboring conserved P1 residues (Glu-67, Lys-48, and His-64) show that a hydrogen-bonding network controls the reactivity of the phospho-accepting His (His-45) in Thermotoga maritima CheA. In particular, the conservative mutation E67Q dramatically reduces phosphotransfer to P1 without significantly affecting the affinity of P1 for the CheA ATP-binding domain. High resolution crystallographic studies revealed that although all mutants disrupt the hydrogen-bonding network to varying degrees, none affect the conformation of His-45. 15N-NMR chemical shift studies instead showed that Glu-67 functions to stabilize the unfavored N(delta1)H tautomer of His-45, thereby rendering the N(epsilon2) imidazole unprotonated and well positioned for accepting the ATP phosphoryl group. |
| Links |
PubMed Online version:10.1074/jbc.M505316200 |
| Keywords |
Adenosine Triphosphate/chemistry; Chemotaxis; Cloning, Molecular; Crystallography, X-Ray; Histidine/chemistry; Hydrogen; Hydrogen Bonding; Hydrogen-Ion Concentration; Kinetics; Magnetic Resonance Spectroscopy; Models, Chemical; Models, Molecular; Mutagenesis, Site-Directed; Mutation; Phosphorylation; Protein Conformation; Protein Kinases/chemistry; Protein Kinases/physiology; Protein Structure, Tertiary; Thermotoga maritima/enzymology; Thermotoga maritima/physiology |
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