Strains of Escherichia coli K12 heterozygous for the R100-1 tetracycline resistance region were constructed. They carried the wild-type Tetr genes in the chromosome and single site Tets mutations on plasmids. Some heterozygotes could not express tetracycline resistance fully after induction. The mut
Tetracycline-sensitive mutants of the F-like R factors R 100 and R 100-1
β Scribed by T. J. Foster
- Publisher
- Springer
- Year
- 1975
- Tongue
- English
- Weight
- 248 KB
- Volume
- 137
- Category
- Article
- ISSN
- 1617-4615
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β¦ Synopsis
The majority of tetracycline-sensitive (Tets) mutants of R100 and R100-1 are multisite (deletion) mutants. About 50% of these are also transfer-deficient, indicating that the Tetr locus is closely linked to the transfer genes. Tet(s) mutants with single-site lesions are also described.
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The formation of the r-determinant pLC1 and of the RTF pAR132 from the composite plasmid R100.1 was investigated. The general location of IS1 sequences on the three plasmids was established by hybridization of lambdar14 CII::IS1 DNA to EcoRI generated fragments of the various plasmids separated by a
Spontaneous tetracycline-sensitive, transfer-deficient mutants of R100-1 were selected and analysed by genetic complementation tests and with the restriction endonuclease EcoR1. While some of the Tets Tra- mutants were caused by a single deletion event which removed the Tetr genes and extended into
We have cloned the entire r-determinant of the antibiotic resistance plasmid R100.1 on the plasmic vectors pCR1 and pSC201. We find that the hybrid plasmids segregate from cultures in which replication of the vector is blocked. This suggests that the r-det is not capable of autonomous replication.