nucleotide-binding domain (NBD) of Synechococcus elongatus putative sugar kinase (SePSK), Arabidopsis thaliana xylulose kinase-1 (AtXK-1) and similar proteins
This subfamily corresponds to a group of uncharacterized bacterial proteins with similarity to Synechococcus elongatus putative sugar kinase (also known as SePSK; D-ribulose kinase; D-ribulokinase) and Arabidopsis thaliana xylulose kinase-1 (also known as AtXK-1; D-ribulose kinase; D-ribulokinase; inactive xylulose kinase 1). Both kinases exhibit ATP hydrolysis without substrate and can phosphorylate D-ribulose. They belong to the ribulokinase-like carbohydrate kinases, a subfamily of FGGY family carbohydrate kinases. Ribulokinase-like carbohydrate kinases are responsible for the phosphorylation of sugars such as L-ribulose and D-ribulose. Their monomers 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.",