The purification, crystallization and preliminary X-­ray diffraction analysis of dihydrodipicolinate synthase from Clostridium botulinum

In recent years, dihydrodipicolinate synthase (DHDPS; EC 4.2.1.52) has received considerable attention from both mechanistic and structural viewpoints. This enzyme, which is part of the diaminopimelate pathway leading to lysine, couples (S)-aspartate-β-semialdehyde with pyruvate via a Schiff base to a conserved active-site lysine. In this paper, the expression, purification, crystallization and preliminary X-ray diffraction analysis of DHDPS from Clostridium botulinum, an important bacterial pathogen, are presented. The enzyme was crystallized in a number of forms, predominantly using PEG precipitants, with the best crystal diffracting to beyond 1.9 Å resolution and displaying P4₂2₁2 symmetry. The unit-cell parameters were a = b = 92.9, c = 60.4 Å. The crystal volume per protein weight (V_M) was 2.07 ų Da⁻¹, with an estimated solvent content of 41%. The structure of the enzyme will help guide the design of novel therapeutics against the C. botulinum pathogen.