Probing the antibiotic target MurA from Staphylococcus aureus and Bacillus subtilis

Abstract

MurA (UDP-N-acetylglucosamine enolpyruvyl transferase) catalyzes the first committed step in the biosynthesis of cell wall peptidoglycan. Because this pathway is absent in mammals, MurA is an attractive target for the development of antimicrobial agents. While Escherichia coli and all other Gram-negative bacteria possess only one copy of the MurA gene, analyses of the genomes of several Gram-positive bacteria reveal the existence of two MurA genes, termed MurA1 and MurA2.

The research presented here focuses on the cloning, expression, purification and kinetic characterization of the MurA enzymes from two Gram-positive organisms: Staphylococcus aureus and Bacillus subtilis. Sequence analysis indicates that all genes are complete and that the enzymes contain the important catalytic residues previously identified in E. cloacae MurA. Kinetic characterization revealed that the enzymes from both organisms are active and are inhibited by fosfomycin.