HPTransfase is a family of essential histidine phosphotransferases. It controls the activity of the master bacterial cell-cycle regulator CtrA through phosphorylation. It behaves as a homodimer by adopting the domain architecture of the intracellular part of class I histidine kinases. Each subunit consists of two distinct domains: an N-terminal helical hairpin domain and a C-terminal [alpha]/[beta] domain. The two N-terminal domains are adjacent within the dimer, forming a four-helix bundle. The C-terminal domain adopts an atypical Bergerat ATP-binding fold [1].

1: Structural insights into ChpT, an essential dimeric histidine phosphotransferase regulating the cell cycle in Caulobacter crescentus. Fioravanti A, Clantin B, Dewitte F, Lens Z, Verger A, Biondi EG, Villeret V; Acta Crystallogr Sect F Struct Biol Cryst Commun. 2012;68:1025-1029. PMID:22949187