Protein histidine kinase (CheA)

 

Chemotaxis Receptor A (CheA) is involved in the cytoplasmic phosphorylation cascade that couples changes in bacterial swimming behaviour to the external concentrations of attractants and repellents. CheA catalyses the trans-phosphorylation of CheY to generate intracellular signals between the membrane-spanning chemoreceptors and the flagellar motor. The CheA homodimer responds to asymmetric activation. Although there are two ATP-binding sites, one per CheA dimer, only a single binding domain at any given time can participate in catalysis. An aspartate reside of the chemoreceptor CheY is specifically phosphorylated as part of the chemotaxis cascade.

 

Reference Protein and Structure

Sequence
Q56310 UniProt (2.7.13.3) IPR008207 (Sequence Homologues) (PDB Homologues)
Biological species
Thermotoga maritima MSB8 (Bacteria) Uniprot
PDB
1i58 - STRUCTURE OF THE HISTIDINE KINASE CHEA ATP-BINDING DOMAIN IN COMPLEX WITH ATP ANALOG ADPCP AND MAGNESIUM (1.6 Å) PDBe PDBsum 1i58
Catalytic CATH Domains
3.30.565.10 CATHdb (see all for 1i58)
Cofactors
Magnesium(2+) (1) Metal MACiE
Click To Show Structure

Enzyme Reaction (EC:2.7.-.-)

aspartate residue
CHEBI:32471ChEBI
+
ATP(3-)
CHEBI:57299ChEBI
→
ADP(3-)
CHEBI:456216ChEBI
+
4-phospho-L-aspartic acid residue
CHEBI:137319ChEBI

Enzyme Mechanism

Introduction

This kinase first phosphorylates His45, the phosphate group is then passed on to the nucleophilic Asp of the CheY substrate.

Catalytic Residues Roles

UniProt PDB* (1i58)
Asn409 Asn409(58)A Helps orient the ATP substrate, activating and stabilising it during the initial phosphorylation of the nucleophilic histidine residue and binds Mg2+ ion. hydrogen bond donor, metal ligand, electrostatic stabiliser, steric role
His45 Not found Acts as a nucleophile, abstracting the terminal phosphate group from the ATP substrate and passing it onto the aspartate residue of the CheY substrate. covalently attached, hydrogen bond donor, nucleophile, nucleofuge, activator
Glu67 Not found Activates the nucleophilic histidine residue. increase nucleophilicity, hydrogen bond acceptor, electrostatic stabiliser
*PDB label guide - RESx(y)B(C) - RES: Residue Name; x: Residue ID in PDB file; y: Residue ID in PDB sequence if different from PDB file; B: PDB Chain; C: Biological Assembly Chain if different from PDB. If label is "Not Found" it means this residue is not found in the reference PDB.

Chemical Components

bimolecular nucleophilic substitution, intermediate formation, overall product formed, overall reactant used, enzyme-substrate complex formation, intermediate collapse, dephosphorylation, enzyme-substrate complex cleavage, native state of enzyme regenerated, inferred reaction step

References

  1. Levit MN et al. (1999), Biochemistry, 38, 6651-6658. Mechanism of CheA Protein Kinase Activation in Receptor Signaling Complexes†. DOI:10.1021/bi982839l. PMID:10350484.
  2. Shi T et al. (2011), J Phys Chem B, 115, 11895-11901. Mechanism for the autophosphorylation of CheA histidine kinase: QM/MM calculations. DOI:10.1021/jp203968d. PMID:21910494.
  3. Zhang J et al. (2005), J Am Chem Soc, 127, 11709-11719. Dynamic Mechanism for the Autophosphorylation of CheA Histidine Kinase:  Molecular Dynamics Simulations. DOI:10.1021/ja051199o. PMID:16104748.
  4. Bilwes AM et al. (2001), Nat Struct Biol, 8, 353-360. Nucleotide binding by the histidine kinase CheA. DOI:10.1038/86243. PMID:11276258.
  5. Bilwes AM et al. (1999), Cell, 96, 131-141. Structure of CheA, a Signal-Transducing Histidine Kinase. DOI:10.1016/s0092-8674(00)80966-6. PMID:9989504.

Step 1. His45, activated by Glu67, acts as a nucleophile towards the terminal phosphate group of ATP.

Download: Image, Marvin File

Catalytic Residues Roles

Residue Roles
Asn409(58)A hydrogen bond donor, electrostatic stabiliser, steric role
His45 activator, hydrogen bond donor, covalently attached
Glu67 electrostatic stabiliser, increase nucleophilicity
Asn409(58)A metal ligand
His45 nucleophile

Chemical Components

ingold: bimolecular nucleophilic substitution, intermediate formation, overall product formed, overall reactant used, enzyme-substrate complex formation

Step 2. The nucleophilic Asp of chemoreceptor Y (CheY) attacks the phosphorylated His45, removing the functional group and regenerating the active site.

Download: Image, Marvin File

Catalytic Residues Roles

Residue Roles
His45 activator, hydrogen bond donor
Glu67 hydrogen bond acceptor
His45 nucleofuge

Chemical Components

ingold: bimolecular nucleophilic substitution, intermediate collapse, overall product formed, dephosphorylation, enzyme-substrate complex cleavage, native state of enzyme regenerated, inferred reaction step
Download: Image, Marvin File

Step 1. His45, activated by Glu67, acts as a nucleophile towards the terminal phosphate group of ATP.

Step 2. The nucleophilic Asp of chemoreceptor Y (CheY) attacks the phosphorylated His45, removing the functional group and regenerating the active site.

Products.

Contributors

Sophie T. Williams, Gemma L. Holliday, Charity Hornby