The purification, crystallization and structural elucidation of dTDP-D-glucose 4,6-dehydratase (RmIB), the second enzyme of the dTDP-L-rhamnose synthesis pathway from Salmonella enterica serovar Typhimurium

dTDP-D-glucose 4,6-dehydratase (RmlB) is the second of four enzymes involve d in the dTDP-L-rhamnose pathway and catalyzes the dehydration of dTDP-D-gl ucose to dTDP-4-keto-6-deoxy-D-glucose. The ultimate product of the pathway , dTDP-L-rhamnose, is the precursor of L-rhamnose, which is a key component of the cell wall of many pathogenic bacteria. RmlB from Salmonella enteric a serovar Typhimurium has been overexpressed and purified, and crystals of the enzyme have been grown using the sitting-drop vapour-diffusion techniqu e with lithium sulfate as precipitant. Diffraction data have been obtained to a resolution of 2.8 Angstrom on a single frozen RmlB crystal which belon gs to space group P2(1), with unit-cell parameters a = 111.85, b = 87.77, c = 145.66 Angstrom, beta = 131.53 degrees. The asymmetric unit contains fou r monomers in the form of two RmlB dimers with a solvent content of 62%. A molecular-replacement solution has been obtained and the model is currently being refined.