The ABC transporter Tba of <Emphasis Type="Italic">Amycolatopsis balhimycina</Emphasis> is required for efficient export of the glycopeptide antibiotic balhimycin |
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Authors: | R Menges G Muth W Wohlleben E Stegmann |
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Institution: | 1.Lehrstuhl für Mikrobiologie/Biotechnologie, Mikrobiologisches Institut,Universit?t Tübingen,Tübingen,Germany |
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Abstract: | All known gene clusters for glycopeptide antibiotic biosynthesis contain a conserved gene supposed to encode an ABC-transporter.
In the balhimycin-producer Amycolatopsis balhimycina this gene (tba) is localised between the prephenate dehydrogenase gene pdh and the peptide synthetase gene bpsA. Inactivation of tba in A. balhimycina by gene replacement did not interfere with growth and did not affect balhimycin resistance. However, in the supernatant of
the tba mutant RM43 less balhimycin was accumulated compared to the wild type; and the intra-cellular balhimycin concentration was
ten times higher in the tba mutant RM43 than in the wild type. These data suggest that the ABC transporter encoded in the balhimycin biosynthesis gene
cluster is not involved in resistance but is required for the efficient export of the antibiotic. To elucidate the activity
of Tba it was heterologously expressed in Escherichia coli with an N-terminal His-tag and purified by nickel chromatography. A photometric assay revealed that His6-Tba solubilised in dodecylmaltoside possesses ATPase activity, characteristic for ABC-transporters. |
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Keywords: | Vancomycin Antibiotic resistance Combinatorial biosynthesis Actinomycetales |
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