| Type: | Domain | Name: | DhaL domain |
| Description: | Dihydroxyacetone (Dha) kinases are a family of sequence-conserved enzymes that phosphorylate dihydroxyacetone, glyceraldehyde and other short-chain ketoses and aldoses. They can be divided into two groups according to the source of high-energy phosphate that they utilise, either ATP or phosphoenolpyruvate (PEP). The ATP-dependent forms are the two-domain Dha kinases (DAK), which occur in animals, plants and eubacteria. They consist of a Dha binding (K) and an ATP binding (L) domain. The PEP-dependent forms occur only in eubacteria and a few archaebacteria and consist of three subunits. Twosubunits, DhaK and DhaL, are homologous to the K and L domains. Intriguingly, the ADP moiety is not exchanged for ATP but remains permanently bound to theDhaL subunit where it is rephosphorylated in situ by the third subunit, DhaM, which is homologous to the IIA domain of the mannose transporter of thebacterial PEP:sugar phosphotransferase system (PTS) [, ].The DhaL domain consists of eight antiparallel alpha-helices arranged in an up-and-down geometry and aligned on a circle. This results inthe formation of a helix barrel enclosing a deep pocket. The helices are amphipathic with the hydrophobic side chains directed into the pocket of thebarrel and with the polar residues exposed. The nucleotide is bound on the top of the barrel [, ].The DhaL alpha helix barrel fold appears not only as C-terminal domain in Dha kinases but also as N-terminal domain in a family of two-domain proteins withunknown function. One representative example is YfhG of Lactococcus lactis []. | Short Name: | DhaL_dom |
