Cloning and expression of Staphylococcus aureus and Treptococcus pyogenes murD genes encoding uridine diphosphate N-acetylmuramoyl-L-alanine:D-glutamate ligases.

Bacterial UDP-N-acetylmuramyl-L-alanine:D-glutamate ligase (MurD), a cytoplasmic peptidoglycan biosynthetic enzyme, catalyzes the ATP-dependent addition of D-glutamate to an alanyl residue of the UDP-N-acetylmuramyl-L-alanine precursor, generating the dipeptide. The murD gene was cloned from both Staphylococcus aureus and Streptococcus pyogenes. Sequence analysis of the S. aureus murD gene revealed an open reading frame of 449 amino acids. The deduced aa sequence of S. aureus MurD is highly homologous to MurD from Escherichia coli, Haemophilus influenzae, Bacillus subtilis and St. pyogenes. Recombinant MurD protein from both S. aureus and St. pyogenes was separately overproduced in E. coli and purified as His-tagged fusion. Both recombinant enzymes catalyzed the ATP-dependent addition of D-glutamate to the precursor sugar peptide.