Sequence homology between the tetracycline-resistance determinants of Tn10 and pBR322 |
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Authors: | T T Nguyen K Postle K P Bertrand |
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Institution: | Department of Biochemistry, The University of Sydney, Sydney N.S.W., 2006 Australia Tel. (02) 6922504 |
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Abstract: | The Tn10 tetracycline resistance gene, tetA, encodes a tetracycline-inducible protein with an apparent Mr of 36 X 10(3). We have determined the nucleotide sequence of the Tn10 tetA gene. The extent of the tetA gene was determined by analysis of amino-terminal and carboxy-terminal deletion mutants. We conclude that a single Tn10 gene, the tetA gene, is sufficient to confer tetracycline resistance. The predicted Mr of the tetA protein is 43.2 X 10(3). The sequence homology between the Tn10 tetA gene and the pBR322 tetracycline resistance determinant (49% nucleotide homology, 44% amino acid homology) indicates that these phenotypically distinct tetracycline-resistance determinants must have evolved from a common ancestral sequence. The markedly hydrophobic character of the predicted amino acid sequences of the Tn10 tetA and pBR322 tet-coded proteins suggests that a substantial portion of these proteins may be embedded within the cytoplasmic membrane. |
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Keywords: | Cosmid vector chromosome terminus recombinant DNA library restriction map amp ampicillin Δ deletion EtBr ethidium bromide kb kilobase pairs MDal megadaltons SDS sodium dodecyl sulfate SSC |
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