cd07770

Gluconate kinases; a subfamily of the FGGY family of carbohydrate kinases; This subfamily is composed of a group of gluconate kinases (GntK, also known as gluconokinase; EC 2.7.1.12) encoded by the gntK gene, which catalyzes the ATP-dependent phosphorylation of D-gluconate and produce 6-phospho-D-gluconate and ADP. The presence of Mg2+ might be required for catalytic activity. The prototypical member of this subfamily is GntK from Lactobacillus acidophilus. Unlike Escherichia coli GntK, which belongs to the superfamily of P-loop containing nucleoside triphosphate hydrolases, members in this subfamily are homologous to glycerol kinase, xylulose kinase, and rhamnulokinase from Escherichia coli. They have been classified as members of the FGGY family of carbohydrate kinases, which contain two large domains separated by a deep cleft that forms the active site. This model spans both the N-terminal domain, which adopts a ribonuclease H-like fold, and the structurally related C-terminal domain. Some uncharacterized homologous sequences are also included in this subfamily. The Lactobacillus gnt operon contains a single gntK gene. The gnt operons of some bacteria, such as Corynebacterium glutamicum, have two gntK genes. For example, the C. glutamicum gnt operon has both a gluconate kinase gntV gene (also known as gntK) and a second hypothetical gntK gene (also known as gntK2). Both gluconate kinases encoded by these genes belong to this family, however the protein encoded by C. glutamicum gntV is not included in this model as it is truncated in the C-terminal domain.