Structure of D-ribulose 5-phosphate 3-epimerase from Synechocystis to 1.6 Å resolution

The crystal structure of D-ribulose 5-phosphate 3-epimerase (RPE) from the cyanobacterium Synechocystis was determined by X-­ray crystallography to 1.6 Å resolution. The enzyme, which catalyzes the epimerization of D-ribulose 5-phosphate and D-­xylulose 5-phosphate, assembles as a hexamer of (β/α)₈-barrels in the crystallographic asymmetric unit. The active site is highly similar to those of two previously reported RPEs and provides further evidence for essential catalytic roles for several active-site residues.