The crystal structure of dihydrodipicolinate reductase from the human-pathogenic bacterium Bartonella henselae strain Houston-1 at 2.3Aa 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, 200mM sodium acetate, 100mM sodium citrate tribasic pH 5.5 and were shown to diffract to 2.3Aa resolution. They belonged to space group P4 sub(3)22, with unit-cell parameters a = 109.38, b = 109.38, c = 176.95Aa. R sub(r.i.m.) was 0.11, R sub(work) was 0.177 and R sub(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 super(+) was found to be bound to one monomer, which resulted in a closed conformational change in the N-terminal domain. The cloning, expression, purification, crystallization and X-ray diffraction analysis of dihydrodipicolinate reductase from the human-pathogenic bacterium B. henselae, the causative bacterium of cat-scratch disease, are reported.