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Characterization of Saccharomyces cerevisiae mutants supersensitive to aminoglycoside antibiotics
Abstract:
We describe mutants of Saccharomyces cerevisiae that are more sensitive than the wild type to the aminoglycoside antibiotics G418, hygromycin B, destomycin A, and gentamicin X2. In addition, the mutants are sensitive to apramycin, kanamycin B, lividomycin A, neamine, neomycin, paromomycin, and tobramycin--antibiotics which do not inhibit wild-type strains. Mapping studies suggest that supersensitivity is caused by mutations in at least three genes, denoted AGS1, AGS2, and AGS3 (for aminoglycoside antibiotic sensitivity). Mutations in all three genes are required for highest antibiotic sensitivity; ags1 ags2 double mutants have intermediate antibiotic sensitivity. AGS1 was mapped 8 centimorgans distal from LEU2 on chromosome III. Analyses of yeast strains transformed with vectors carrying antibiotic resistance genes revealed that G418, gentamicin X2, kanamycin B, lividomycin A, neamine, and paromomycin are inactivated by the Tn903 phosphotransferase and that destomycin A is inactivated by the hygromycin B phosphotransferase. ags strains are improved host strains for vectors carrying the phosphotransferase genes because a wide spectrum of aminoglycoside antibiotics can be used to select for plasmid maintenance.
Insights
Researchers identified novel Saccharomyces cerevisiae mutants exhibiting heightened sensitivity to multiple aminoglycoside antibiotics. These "AGS" mutants are valuable for selecting plasmid maintenance using a broad range of antibiotics.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Aminoglycoside antibiotics are crucial for treating bacterial infections.
- Understanding resistance and sensitivity mechanisms in model organisms like Saccharomyces cerevisiae is vital for antibiotic development.
- Previous studies have identified some yeast mutants with altered antibiotic sensitivity.
Purpose of the Study:
- To characterize novel Saccharomyces cerevisiae mutants with enhanced sensitivity to a wide array of aminoglycoside antibiotics.
- To identify the genetic basis of this supersensitivity.
- To evaluate the utility of these mutants as improved host strains for genetic engineering.
Main Methods:
- Chemical mutagenesis of Saccharomyces cerevisiae.
- Phenotypic screening for increased sensitivity to various aminoglycoside antibiotics.
- Genetic mapping of mutations conferring antibiotic sensitivity.
- Analysis of antibiotic resistance gene expression in transformed yeast strains.
Main Results:
- Identified Saccharomyces cerevisiae mutants (ags1, ags2, ags3) exhibiting supersensitivity to multiple aminoglycoside antibiotics, including those ineffective against wild-type strains.
- Demonstrated that mutations in at least three genes (AGS1, AGS2, AGS3) are necessary for maximal antibiotic sensitivity.
- Mapped the AGS1 gene to chromosome III.
- Confirmed that specific aminoglycoside antibiotics are inactivated by phosphotransferase enzymes, suggesting potential for selection strategies.
Conclusions:
- Novel Saccharomyces cerevisiae mutants with broad aminoglycoside antibiotic supersensitivity have been discovered.
- These 'AGS' mutants represent valuable tools for genetic studies and for developing improved host strains in yeast biotechnology.
- The findings contribute to a deeper understanding of aminoglycoside antibiotic action and resistance mechanisms.