nucleotide-binding domain (NBD) of L-fuculokinase (FK) and similar proteins
FK (EC 2.7.1.51), also called L-fuculose kinase, catalyzes the ATP-dependent phosphorylation of L-fuculose to produce L-fuculose-1-phosphate and ADP. It can also phosphorylate, with lower efficiency, D-ribulose, D-xylulose and D-fructose. The presence of Mg2+ or Mn2+ is required for enzymatic activity. FKs belong to the FGGY family of carbohydrate kinases, the monomers of which contain two large domains, which are separated by a deep cleft that forms the active site. This model includes 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.",