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Chromosomal mutations causing resistance to tetracycline in Bacillus subtilis.
Molecular & General Genetics : MGG
|January 1, 1979
Summary
Researchers identified two new tetracycline resistance genes, tetA and tetB, in Bacillus subtilis. The tetA mutation alters ribosomal protein S10, conferring in vitro resistance, while tetB
Area of Science:
- Microbiology and Molecular Genetics
- Bacterial Genetics and Antibiotic Resistance
Background:
- Antibiotic resistance is a significant global health concern.
- Understanding the genetic basis of resistance in bacteria like Bacillus subtilis is crucial for developing new strategies.
- Previous studies have identified various mechanisms of tetracycline resistance.
Purpose of the Study:
- To isolate and characterize novel chromosomal mutations conferring tetracycline resistance in Bacillus subtilis.
- To elucidate the genetic loci and molecular mechanisms underlying these resistance phenotypes.
Main Methods:
- Ethylmethanesulfonate mutagenesis was employed to generate mutations in Bacillus subtilis.
- Mutants resistant to tetracycline were selected and analyzed.
- Two-dimensional polyacrylamide gel electrophoresis was used to assess ribosomal protein alterations.
- In vitro assays measuring polyphenylalanine synthesis were performed to quantify ribosomal resistance.
- Genetic mapping techniques were utilized to determine the chromosomal location of the resistance genes.
Main Results:
- Two distinct classes of tetracycline resistance mutations, designated tetA and tetB, were identified.
- The tetA mutation resulted in an altered 30S ribosomal protein S10, leading to elevated in vitro tetracycline resistance.
- The tetA locus was mapped adjacent to the tuf gene within the Bacillus subtilis ribosomal protein gene cluster.
- The tetB mutation did not affect ribosomal proteins, and cells exhibited wild-type sensitivity to tetracycline in vitro.
- The tetB mutation was mapped proximal to the cysA14 locus.
Conclusions:
- Two novel genetic determinants, tetA and tetB, contribute to tetracycline resistance in Bacillus subtilis.
- The tetA-mediated resistance involves alterations in ribosomal protein S10, directly impacting ribosomal function.
- The tetB resistance mechanism remains uncharacterized at the molecular level but is genetically distinct from tetA.