nucleotide-binding domain (NBD) of gluconate kinase (GntK) and similar proteins
GntK (EC 2.7.1.12), also known as gluconokinase, 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 of 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.
Comment:catalytic residues (Asp, Thr, Asp) conserved in the FGGY family
Comment:Two Asp residues probably form a metal cofactor binding site and the second Asp residue acts as a catalytic base.
Comment:It has been proposed that the first Asp coordinates and positions the MgATP, and (in concert with the Mg2+) stabilizes the ADP leaving group during the phospho transfer. The second Asp would act as a general base during catalysis, assisting the removal of a proton from the attacking hydroxyl group. The Thr could stabilize the transition state.
Jiyao W et al.(2023). "The conserved domain database in 2023.",