Evolved neomycin phosphotransferase from an isolate of Klebsiella pneumoniae

K. Y. Lee, J. D. Hopkins, Michael Syvanen

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12 Scopus citations


A new aminoglycoside resistance gene (aphA1-IAB) confers high-level resistance to neomycin. The sequence of aphA1-IAB is closely related to aphA1 found in the transposons TN4352, TN903 and Tn602. For example, aphA1-IAB differs from aphA1-903 at five nucleotides that result in four amino acid replacements. The enzyme encoded by aphA1-IAB has a significantly higher turnover number with neomycin, kanamycin and G418 as substrates than does the aphA1-903 enzyme. A parsimonious phylogenetic tree suggests that aphA1-IAB evolved from an ancestral form that is closely related or identical to the aphA1 found in Tn903. The excess of replacement substitutions over silent substitutions in aphA1-IAB, as well as its convergence toward aphA3 from Staphylococcus aureus, is indicative of selective evolution. Our hypothesis to explain these results is that aphA1-IAB evolved under the selective pressure of neomycin use in relatively recent times.

Original languageEnglish (US)
Pages (from-to)2039-2046
Number of pages8
JournalMolecular Microbiology
Issue number8
StatePublished - Aug 1991

ASJC Scopus subject areas

  • Molecular Biology
  • Microbiology


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