Three-dimensional solution structure of bottromycin A ₂: A potent antibiotic active against methicillin-resistant Staphylococcus aureus and vancomycin- resistant Enterococci

The three-dimensional (3D) structure of bottromycin A ₂, a natural anti-methicillin-resistant Staphylococcus aureus (MRSA) and anti-vancomycin-resistant Enterococci (VRE) agent consisting of seven amino acids, has been investigated through NMR spectroscopy. On the basis of 57 experimental constraints, a total of 34 converged structures were obtained. The average pairwise atomic root mean square difference is 0.74±0.59 Å for all heavy atoms. The resulting structure indicates an interesting feature in that the three C-terminal residues of bottromycin A ₂ fold back on the 12-membered cyclic skeleton made by the four N-terminal residues. Thus, MePro(2) and Thia-β-Ala-OMe(7), modification of which significantly affects the antibacterial activities of bottromycin A ₂, are located on one side of its 3D structure. These distinct structural features might be important for the binding of bottromycin A ₂ with the bacterial ribosome.