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Mapping of the mecillinam-resistant, round morphological mutants of Escherichia coli
Abstract:
Genes responsible for round morphology in mecillinam-resistant, round morphological mutants of Escherichia coli have been mapped. Three mutants, called rodX, mapped at around 14 min, and two, called rodY, mapped at around 70 min by P1 transduction. These are either the same or very close to the loci reported, respectively, for the rodA (H. Matsuzawa, K. Hayakawa, T. Sato, and K. Imahori, J. Bacteriol. 115:436-442, 1973) and envB genes (B. Westling-Häggström and S. Normark, J. Bacteriol. 123:75-82, 1975). This suggests that mecillinam can be used very efficiently to select for found morphological mutants of rodA and envB after nitrosoguanidine treatment.
Insights
Researchers mapped genes controlling round cell shape in mecillinam-resistant Escherichia coli mutants. Mecillinam efficiently selects for rodA and envB mutants, aiding in understanding bacterial morphology.
Area of Science:
- Microbiology
- Bacterial Genetics
- Cell Morphology
Background:
- Mecillinam is an antibiotic that targets bacterial cell wall synthesis.
- Mutations in Escherichia coli can lead to altered cell morphology, including a round shape.
- Identifying genes responsible for these morphological changes is crucial for understanding bacterial growth and development.
Purpose of the Study:
- To map the genetic loci of spontaneous round morphological mutants in mecillinam-resistant Escherichia coli.
- To investigate the relationship between mecillinam resistance and specific gene mutations affecting cell shape.
- To evaluate mecillinam as a selective agent for isolating morphological mutants.
Main Methods:
- P1 transduction was used to map the genetic locations of mutations in resistant mutants.
- Nitrosoguanidine was employed as a mutagen to induce mutations.
- Phenotypic analysis focused on cell morphology (round vs. rod shape).
Main Results:
- Three mutants, designated rodX, were mapped to approximately 14 minutes on the E. coli chromosome.
- Two mutants, designated rodY, were mapped to approximately 70 minutes.
- The mapped loci (rodX and rodY) correspond closely to previously identified rodA and envB genes, respectively.
Conclusions:
- The rodX mutations are likely allelic or closely linked to the rodA gene, involved in cell shape determination.
- The rodY mutations are likely allelic or closely linked to the envB gene, also influencing cell morphology.
- Mecillinam serves as an effective selective agent for isolating rodA and envB morphological mutants after mutagenesis.