title: Potential for reduction of streptogramin A resistance revealed by structural analysis of acetyltransferase VatA.
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-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.
authors.affiliation: Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada Center for Structural Genomics of Infectious Diseases (CSGID).
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Stogios
authors.affiliation: Center for Structural Genomics of Infectious Diseases (CSGID) Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
authors.forename: Misty L
authors.initials: ML
authors.lastname: Kuhn
authors.affiliation: Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada Center for Structural Genomics of Infectious Diseases (CSGID).
authors.forename: Elena
authors.initials: E
authors.lastname: Evdokimova
authors.affiliation: Unité des Agents Antibactériens, Institut Pasteur, Paris, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Courvalin
authors.affiliation: Center for Structural Genomics of Infectious Diseases (CSGID) Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
authors.forename: Wayne F
authors.initials: WF
authors.lastname: Anderson
authors.affiliation: Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada Center for Structural Genomics of Infectious Diseases (CSGID) alexei.savchenko@utoronto.ca.
authors.forename: Alexei
authors.initials: A
authors.lastname: Savchenko
mesh_terms: D000105:Acetyl Coenzyme A / Q000737:chemistry; D000123:Acetyltransferases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics; D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D024881:Drug Resistance, Bacterial / Q000235:genetics; D015870:Gene Expression; D006090:Gram-Negative Bacteria / Q000737:chemistry / Q000201:enzymology; D006094:Gram-Positive Bacteria / Q000737:chemistry / Q000201:enzymology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment; D025364:Streptogramin A / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D011994:Recombinant Proteins; D000105:Acetyl Coenzyme A; D025364:Streptogramin A; D000123:Acetyltransferases