Analysis of the tet gene of plasmid pCIS7 isolated from Bacillus subtilis.
We have previously shown that plasmid pCIS7, which contains 11.5 kb of Bacillus subtilis DNA isolated from a tetracycline-sensitive (TcS) strain, confers Tc resistance when integrated and amplified in the chromosome of TcS B. subtilis 168trpC2 [Ives and Bott, J. Bacteriol. 171 (1989) 1801-1810]. Here, we report that the number of integrated plasmid sequences required to confer Tc resistance is greater than the 20 copies seen with increasing chloramphenicol selection and, by dot-blot analysis, exceeds 100 copies per cell. The amplification is accompanied by a corresponding increase in mRNA encoding the tet gene. The tet gene sequence of pCIS7 has been compared to B. subtilis tetGSY908 [Sakaguchi et al., Biochim. Biophys. Acta. 94 (1988) 49-57] and other Gram-positive tet genes. The tet gene of pCIS7 is a member of the class L TcR determinants, and probably confers Tc resistance by increasing the efflux of Tc from the bacterial cell.
Ives
C L
CL
Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill 27599-7290.
Bott
K F
KF
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D011815:R Factors; D012097:Repressor Proteins / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D013753:Tetracycline Resistance / Q000235:genetics*
D004269:DNA, Bacterial; D012097:Repressor Proteins; C034811:tetracycline resistance-encoding transposon repressor protein