title: Sequence homology between the tetracycline-resistance determinants of Tn10 and pBR322.
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.
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D004251:DNA Transposable Elements; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D005798:Genes, Bacterial; D010957:Plasmids; D013752:Tetracycline / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D013752:Tetracycline