Crystal structure of Staphylococcus aureus transglycosylase in complex with a lipid II analog and elucidation of peptidoglycan synthesis mechanism

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 109; no. 17; pp. 6496 - 6501
• Main Authors: Huang, Chia-Ying, Shih, Hao-Wei, Lin, Li-Ying, Tien, Yi-Wen, Cheng, Ting-Jen Rachel, Cheng, Wei-Chieh, Wong, Chi-Huey, Ma, Che
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 24.04.2012; National Acad Sciences
• Subjects: Amino Acid Sequence; Antibiotic resistance; Antibiotics; bacteria; Biological Sciences; Cell walls; Crystal structure; Crystallography, X-Ray; Diphosphates; Drug development; Drug resistance; Electron density; Enzymatic activity; enzyme activity; Enzymes; Glycosyltransferase; Glycosyltransferases - chemistry; Infection; Lipids; Lipids - chemistry; Models, Molecular; moenomycin; Molecular Sequence Data; Molecular structure; Mutagenesis; Peptidoglycan - biosynthesis; peptidoglycans; Phosphates; Physical Sciences; Polysaccharides; Protein Conformation; Sequence alignment; Sequence Homology, Amino Acid; Staphylococcus aureus; Staphylococcus aureus - enzymology; Staphylococcus infections
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1203900109

Bacterial transpeptidase and transglycosylase on the surface are essential for cell wall synthesis, and many antibiotics have been developed to target the transpeptidase; however, the problem of antibiotic resistance has arisen and caused a major threat in bacterial infection. The transglycosylase has been considered to be another excellent target, but no antibiotics have been developed to target this enzyme. Here, we determined the crystal structure of the Staphylococcus aureus membrane-bound transglycosylase, monofunctional glycosyltransferase, in complex with a lipid II analog to 2.3 Å resolution. Our results showed that the lipid II-contacting residues are not only conserved in WT and drug-resistant bacteria but also significant in enzymatic activity. Mechanistically, we proposed that K140 and R148 in the donor site, instead of the previously proposed E156, are used to stabilize the pyrophosphate-leaving group of lipid II, and E100 in the acceptor site acts as general base for the 4-OH of GlcNAc to facilitate the transglycosylation reaction. This mechanism, further supported by mutagenesis study and the structure of monofunctional glycosyltransferase in complex with moenomycin in the donor site, provides a direction for antibacterial drugs design.