InterPro domain: IPR036097

This entry represents the dimerisation and phosphoacceptor domain superfamily found in some histidine kinases. Signal transducing histidine kinases are the key elements in two-component signal transduction systems, which control complex processes such as the initiation of development in microorganisms [ 1 ]. Examples of histidine kinases are EnvZ, which plays a central role in osmoregulation [ 2 ]. Histidine kinases usually have an N-terminal ligand-binding domain and a C-terminal kinase domain, but other domains may also be present. The kinase domain is responsible for the autophosphorylation of the histidine with ATP, the phosphotransfer from the kinase to an aspartate of the response regulator, and the phosphotransfer from aspartyl phosphate back to ADP or to water [ 3 ]. The homodimeric domain includes the site of histidine autophosphorylation and phosphate transfer reactions. The structure of the homodimeric domain comprises a closed, four-helical bundle with a left-handed twist, formed by two identical alpha-hairpin subunits.

1. Protein aspartate phosphatases control the output of two-component signal transduction systems. Trends Genet. 12, 97-101
2. Solution structure of the homodimeric core domain of Escherichia coli histidine kinase EnvZ. Nat. Struct. Biol. 6, 729-34
3. Bacteriophytochromes: new tools for understanding phytochrome signal transduction. Semin. Cell Dev. Biol. 11, 511-21