Purification, crystallization and molecular symmetry of CDP-D-glucose 4,6-dehydratase from Yersinia pseudotuberculosis.

The enzyme CDP-d-glucose 4,6-dehydratase (EC 4.2.1.45) is an NAD+-dependent oxidoreductase which catalyzes the irreversible conversion of CDP-d-glucose to CDP-4-keto-6-deoxy-d-glucose. The product of this reaction is an intermediate in the synthesis of all CDP-­linked 3,6-dideoxyhexoses, an important class of antigenic determinants found in the lipopolysaccharide layer of Gram-negative bacteria. Crystals of a recombinant form of this enzyme from Yersinia pseudotuberculosis have been grown in two crystal forms, both possessing pseudo-translational non-crystallographic symmetry, with dramatically different diffraction characteristics. A complete 1.8 A data set has been collected from the primitive orthorhombic crystal form, for which the non-crystallographic symmetry is described in detail.