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Genetic analysis of carbohydrate transport-deficient mutants of Salmonella typhimurium
Abstract:
Mutants (car) isolated from Salmonella typhimurium were unable to utilize or ferment the following carbohydrates (all d-configuration): glucose, fructose, mannose, N-acetylglucosamine, sorbitol, mannitol, maltose, melibiose, and glycerol. The mutants did utilize galactose, glucose 6-phosphate, gluconic acid, glucuronic acid, pyruvate, and l-lactate. Biochemical analysis showed that there were two classes of mutants, each lacking one component of a phosphotransferase system. CarA mutants were deficient in enzyme I; carB lacked the phosphate carrier protein, HPr. Mapping experiments showed that the carA gene was located near pro; the carB gene mapped near purC.
Insights
Salmonella typhimurium mutants unable to utilize specific carbohydrates were identified. These mutants were deficient in either enzyme I or the HPr protein of the phosphotransferase system.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Carbohydrate metabolism is crucial for bacterial survival and virulence.
- Phosphotransferase systems (PTS) are key for nutrient uptake and regulation in bacteria like Salmonella typhimurium.
Purpose of the Study:
- To characterize Salmonella typhimurium mutants with defects in carbohydrate utilization.
- To identify the specific components of the phosphotransferase system affected in these mutants.
Main Methods:
- Isolation and characterization of carbohydrate utilization mutants (car) in Salmonella typhimurium.
- Biochemical assays to determine enzyme deficiencies.
- Genetic mapping to locate the mutated genes.
Main Results:
- Mutants were unable to utilize a range of d-configured carbohydrates including glucose, maltose, and glycerol, but could utilize galactose and pyruvate.
- Two distinct mutant classes were identified: carA mutants deficient in enzyme I, and carB mutants lacking the HPr protein.
- The carA gene was mapped near pro, and the carB gene near purC.
Conclusions:
- The phosphotransferase system, specifically enzyme I and HPr, plays a vital role in Salmonella typhimurium's ability to utilize various carbohydrates.
- Genetic loci for carA and carB provide valuable markers for further genetic studies in Salmonella typhimurium.