The crystal structure of dihydrodipicolinate reductase from the human-pathogenic bacteriumBartonella henselaestrain Houston-1 at 2.3 Å resolution

In bacteria, the second committed step in the diaminopimelate/lysine anabolic pathways is catalyzed by the enzyme dihydrodipicolinate reductase (DapB). DapB catalyzes the reduction of dihydrodipicolinate to yield tetrahydrodipicolinate. Here, the cloning, expression, purification, crystallization and X-ray diffraction analysis of DapB from the human-pathogenic bacterium Bartonella henselae , the causative bacterium of cat-scratch disease, are reported. Protein crystals were grown in conditions consisting of 5%( w / v ) PEG 4000, 200 m M sodium acetate, 100 m M sodium citrate tribasic pH 5.5 and were shown to diffract to ∼2.3 Å resolution. They belonged to space group P 4 3 22, with unit-cell parameters a = 109.38, b = 109.38, c = 176.95 Å. R r.i.m. was 0.11, R work was 0.177 and R free was 0.208. The three-dimensional structural features of the enzymes show that DapB from B. henselae is a tetramer consisting of four identical polypeptides. In addition, the substrate NADP + was found to be bound to one monomer, which resulted in a closed conformational change in the N-terminal domain.