Crystal structure of an ADP-dependent glucokinase from Pyrococcus furiosus: implications for a sugar-induced conformational change in ADP-dependent kinase.

ADP-dependent kinases are used in the modified Embden-Meyerhoff pathway of certain archaea. Our previous study has revealed a mechanism for ADP-dependent phosphoryl transfer by Thermococcus litoralis glucokinase (tlGK), and its evolutionary relationship with ATP-dependent ribokinases and adenosine kinases (PFKB carbohydrate kinase family members). Here, we report the crystal structure of glucokinase from Pyrococcus furiosus (pfGK) in a closed conformation complexed with glucose and AMP at 1.9A resolution. In comparison with the tlGK structure, the pfGK structure shows significant conformational changes in the small domain and a region around the hinge, suggesting glucose-induced domain closing. A part of the large domain next to the hinge is also shifted accompanied with domain closing. In the pfGK structure, glucose binds in a groove between the large and small domains, and the electron density of O1 atoms for both the alpha and beta-anomer configurations was observed. The structural details of the sugar-binding site of ADP-dependent glucokinase were firstly clarified and then site-directed mutagenesis analysis clarified the catalytic residues for ADP-dependent kinase, such as Arg205 and Asp451 of tlGK. Homology search and multiple alignment of amino acid sequences using the information obtained from the structures reveals that eucaryotic hypothetical proteins homologous to ADP-dependent kinases retain the residues for the recognition of a glucose substrate.