Potential for Reduction of Streptogramin A Resistance Revealed by Structural Analysis of Acetyltransferase VatA.Stogios, P.J., Kuhn, M.L., Evdokimova, E., Courvalin, P., Anderson, W.F., Savchenko, A.
(2014) Antimicrob.Agents Chemother. 58: 7083-7092
- PubMed: 25223995
- DOI: 10.1128/AAC.03743-14
- Primary Citation of Related Structures:  4HUS, 4MYO
- PubMed Abstract:
Combinations of group A and B streptogramins (i.e., dalfopristin and quinupristin) are "last-resort" antibiotics for the treatment of infections caused by Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus and vancomycin-r ...
Combinations of group A and B streptogramins (i.e., dalfopristin and quinupristin) are "last-resort" antibiotics for the treatment of infections caused by Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium. Resistance to streptogramins has arisen via multiple mechanisms, including the deactivation of the group A component by the large family of virginiamycin O-acetyltransferase (Vat) enzymes. Despite the structural elucidation performed for the VatD acetyltransferase, which provided a general molecular framework for activity, a detailed characterization of the essential catalytic and antibiotic substrate-binding determinants in Vat enzymes is still lacking. We have determined the crystal structure of S. aureus VatA in apo, virginiamycin M1- and acetyl-coenzyme A (CoA)-bound forms and provide an extensive mutagenesis and functional analysis of the structural determinants required for catalysis and streptogramin A recognition. Based on an updated genomic survey across the Vat enzyme family, we identified key conserved residues critical for VatA activity that are not part of the O-acetylation catalytic apparatus. Exploiting such constraints of the Vat active site may lead to the development of streptogramin A compounds that evade inactivation by Vat enzymes while retaining binding to their ribosomal target.
Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada Center for Structural Genomics of Infectious Diseases (CSGID).