Crystallization and preliminary X-ray crystallographic analysis of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase from Mycobacterium tuberculosis

The enzymes of the shikimate pathway are attractive targets for new-generation antimicrobial agents. The first step of this pathway is catalysed by 3-deoxy-D-­arabino-heptulosonate-7-phosphate (DAH7P) synthase and involves the condensation of phosphoenolpyruvate (PEP) and erythrose 4-phosphate (E4P) to form DAH7P. DAH7P synthases have been classified into two apparently evolutionarily unrelated types and whereas structural data have been obtained for the type I DAH7P synthases, no structural information is available for their type II counterparts. The type II DAH7P synthase from Mycobacterium tuberculosis was co-expressed as native and selenomethionine-substituted protein with the Escherichia coli chaperonins GroEL and GroES in E. coli, purified and crystallized. Native crystals of M. tuberculosis DAH7P synthase belong to space group P3₁21 or P3₂21 and diffract to 2.5 Å, with unit-cell parameters a = b = 203.61, c = 66.39 Å. There are either two or three molecules in the asymmetric unit. Multiwavelength anomalous diffraction (MAD) phasing using selenomethionine-substituted protein is currently under way.