ABSTRACT: BACKGROUND: Malate synthase catalyzes the second step of the glyoxylate bypass, the condensation of acetyl coenzyme A and glyoxylate to form malate and coenzyme A (CoA). In several microorganisms, the glyoxylate bypass is of general importance to microbial pathogenesis. The predicted malate synthase G of Pseudomonas aeruginosa has also been implicated in virulence of this opportunistic pathogen. RESULTS: Here, we report the verification of the malate synthase activity of this predicted protein and its recombinant production in E. coli, purification and biochemical characterization. The malate synthase G of P. aeruginosa PAO1 has a temperature and pH optimum of 37.5 degrees C and 8.5, respectively. Although displaying normal thermal stability, the enzyme was stable up to incubation at pH 11. The following kinetic parameters of P. aeruginosa PAO1 malate synthase G were obtained: Km glyoxylate (70 microM), Km acetyl CoA (12 microM) and Vmax (16.5 micromol/minutes/millig enzyme). In addition, deletion of the corresponding gene showed that it is a prerequisite for growth on acetate as sole carbon source. CONCLUSIONS: The implication of the glyoxylate bypass in the pathology of various microorganisms makes malate synthase G an attractive new target for antibacterial therapy. The purification procedure and biochemical characterization assist in the development of antibacterial components directed against this target in P. aeruginosa.