A Structural Variation for MurB: X-ray Crystal Structure of Staphylococcus aureus UDP-N-Acetylenolpyruvylglucosamine Reductase (MurB)‡

The X-ray crystal structure of the substrate free form of Staphylococcus aureus UDP-N-acetylenolpyruvylglucosamine reductase (MurB) has been solved to 2.3 A resolution with an R-factor of 20.3% and a free R-factor of 22.3%. While the overall fold of the S. aureus enzyme is similar to that of the homologous Escherichia coli MurB X-ray crystal structure, notable distinctions between the S. aureus and E. coli MurB protein structures occur in residues involved in substrate binding. Analysis of available MurB sequences from other bacteria suggest that the S. aureus MurB structure is representative of a distinct structural class of UDP-N-acetylenolpyruvylglucosamine reductases including Bacillus subtilis and Helicobacter pylori that are characterized by a modified mechanism for substrate binding.