title: Identification of vancomycin resistance protein VanA as a D-alanine:D-alanine ligase of altered substrate specificity.
abstract: High-level glycopeptide resistance in Enterococcus faecium BM4147 is mediated by a 38-kDa protein VanA, whose amino acid sequence is related to Gram-negative D-alanine:D-alanine (D-Ala-D-Ala) ligases [Dutka-Malen, S., Molinas, C., Arthur, M., & Courvalin, P. (1990) Mol. Gen. Genet. 224, 364-372]. We report purification of VanA and demonstrate that it has D-Ala-D-Ala ligase activity but has substantially modified substrate specificity, compared with Gram-negative D-Ala-D-Ala ligases. VanA preferentially condenses D-Ala with D-Met or D-Phe, raising the possibility that its cellular role is to synthesize a modified cell-wall component, which is subsequently not recognized by vancomycin.
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: T D
authors.initials: TD
authors.lastname: Bugg
authors.forename: S
authors.initials: S
authors.lastname: Dutka-Malen
authors.forename: M
authors.initials: M
authors.lastname: Arthur
authors.forename: P
authors.initials: P
authors.lastname: Courvalin
authors.forename: C T
authors.initials: CT
authors.lastname: Walsh
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019729:Carbon-Oxygen Ligases; D002850:Chromatography, Gel; D004352:Drug Resistance, Microbial / Q000502:physiology; D006090:Gram-Negative Bacteria / Q000201:enzymology; D008969:Molecular Sequence Data; D010453:Peptide Synthases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D013291:Streptococcus / Q000187:drug effects / Q000201:enzymology*; D013379:Substrate Specificity; D014640:Vancomycin / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; C071437:VanA ligase, Bacteria; D014640:Vancomycin; D019729:Carbon-Oxygen Ligases; D010453:Peptide Synthases; C019638:D-alanylalanine synthetase