HisB from Mycobacterium tuberculosis: cloning, overexpression in Mycobacterium smegmatis, purification, crystallization and preliminary X-ray crystallographic analysis.

HisB, encoded by open reading frame Rv1601, possesses enzymatic activity as an imidazoleglycerol-phosphate dehydratase in the histidine-biosynthetic pathway of Mycobacterium tuberculosis. A recombinant form of HisB was crystallized in three crystal forms: crystals grown using 20% PEG 1500 as a precipitant belonged to either the cubic space group P432 or the tetragonal space group P4, while an orthorhombic crystal form belonging to space group P2(1)2(1)2 was obtained using 15% PEG 5000 and 10 mM MnCl(2) as precipitant. The structure of HisB in the orthorhombic crystal form was solved by the molecular-replacement method using the crystal structure of its Arabidopsis thaliana counterpart, which shares 47% sequence identity with Rv1601, as the search model.