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.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Amino Acid Sequence
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Bacterial Proteins / genetics
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Bacterial Proteins / isolation & purification
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Bacterial Proteins / metabolism*
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Carbon-Oxygen Ligases*
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Chromatography, Gel
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Drug Resistance, Microbial / physiology
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Gram-Negative Bacteria / enzymology
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Molecular Sequence Data
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Peptide Synthases / genetics
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Peptide Synthases / isolation & purification
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Peptide Synthases / metabolism*
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Streptococcus / drug effects
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Streptococcus / enzymology*
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Substrate Specificity
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Vancomycin / pharmacology*
Substances
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Bacterial Proteins
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VanA ligase, Bacteria
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Vancomycin
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Carbon-Oxygen Ligases
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Peptide Synthases
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D-alanylalanine synthetase