Overexpression, crystallization, and preliminary X-ray crystallographic analysis of shikimate dehydrogenase from Thermotoga maritima.

Shikimate dehydrogenase (SDH), which catalyses the NADPH-dependent reduction of 3-dehydroshikimate to shikimate in the shikimate pathway, is an attractive target for the development of herbicides and antimicrobial agents. Previous structural studies showed that SDH exists in two conformations, an open form and a closed form, and it is believed that the conformational state is crucial to understanding a catalytic mechanism. To facilitate further structural comparisons among SDHs, structural analysis of an SDH from Thermotoga maritima encoded by the Tm0346 gene has been initiated. SDH from T. maritima has been overexpressed in Escherichia coli and crystallized at 296 K using ammonium sulfate as a precipitant. Crystals of T. maritima SDH diffracted to 1.45 Å resolution and belonged to orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a=54.21, b=62.45 and c=68.68 Å. The asymmetric unit contains a monomer, with a corresponding VM of 2.01 Å3 Da(-1) and a solvent content of 38.9% by volume.