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Histidine and aromatic permeases of Salmonella typhimurim
Abstract:
Mutants defective either in the histidine permease (hisP) or in the aromatic permease (aroP) were isolated in Salmonella typhimurium and were characterized. The hisP locus had a 49% linkage to purF by phage transduction. The aroP locus was close to proA. Merozygotes diploid for the hisP gene were constructed by episomal transfer, and hisP(+) was dominant over hisP. The properties of merozygotes are described and discussed. A method for the selection of revertants of hisP mutants was devised. By this method, one of the hisP mutants was characterized as an amber mutant. The specificity of the aromatic permease was investigated by using as substrates analogues of the aromatic amino acids and of histidine.
Insights
Researchers isolated and characterized histidine permease (hisP) and aromatic permease (aroP) mutants in Salmonella typhimurium. They mapped gene loci, studied gene dominance, and identified an amber mutant, providing insights into amino acid transport.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Understanding nutrient transport systems is crucial for microbial physiology.
- Permeases, such as histidine permease (hisP) and aromatic permease (aroP), play vital roles in nutrient uptake.
- Characterization of these permeases aids in elucidating metabolic pathways and genetic regulation.
Purpose of the Study:
- To isolate and genetically characterize mutants defective in histidine permease (hisP) and aromatic permease (aroP) in Salmonella typhimurium.
- To determine the genetic loci of hisP and aroP and their linkage to known genes.
- To investigate the dominance of the hisP gene and the specificity of the aromatic permease.
Main Methods:
- Isolation and characterization of Salmonella typhimurium mutants.
- Phage transduction for genetic mapping of hisP and aroP loci.
- Construction of merozygotes via episomal transfer to study gene dominance.
- Development of a selection method for hisP mutant revertants.
- Substrate analysis using amino acid analogues to determine aromatic permease specificity.
Main Results:
- The hisP locus showed 49% linkage to purF, and the aroP locus was mapped near proA.
- The hisP(+) allele was found to be dominant over the hisP(-) allele in merozygotes.
- A novel selection method allowed for the identification of an amber mutant within the hisP gene.
- The aromatic permease demonstrated specificity towards analogues of aromatic amino acids and histidine.
Conclusions:
- The study successfully characterized hisP and aroP permease mutants in Salmonella typhimurium.
- Genetic mapping and dominance studies provided insights into the organization and regulation of these permease genes.
- The identification of an amber mutant and the investigation of permease specificity contribute to a deeper understanding of amino acid transport mechanisms.