Expression, crystallization and preliminary X-ray crystallographic analysis of cystathionine β-lyase from Acinetobacter baumannii OXA-23

Multidrug-resistant Acinetobacter baumannii (Ab) has emerged as a leading nosocomial pathogen because of its resistance to most currently available antibiotics. Cystathionine β-lyase (CBL), a pyridoxal 5′-phosphate (PLP)-dependent enzyme, catalyzes the second step in the transsulfuration pathway, which is essential for the metabolic interconversion of the sulfur-containing amino acids homocysteine and methionine. The enzymes of the transsulfuration pathway are considered to be attractive drug targets owing to their specificity to microbes and plants. As a potential target for the development of novel antibacterial drugs, the AbCBL protein was expressed, purified and crystallized. An AbCBL crystal diffracted to 1.57 Å resolution and belonged to the trigonal space group P3₁12, with unit-cell parameters a = b = 102.9, c = 136.5 Å. The asymmetric unit contained two monomers, with a corresponding V_M of 2.3 ų Da⁻¹ and a solvent content of 46.9%.