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Cloning and nucleotide sequence of the Salmonella typhimurium pepM gene
Abstract:
The pepM gene coding for a methionine-specific aminopeptidase was cloned from Salmonella typhimurium and its nucleotide sequence determined. The gene encoded a 264 amino acid protein that was homologous to a similar protein from Escherichia coli. The sequence of an overproducer mutant allele, pepM100, contained a single base change in the likely--35 region of the pepM promoter that increased its homology to the consensus promoter sequence. A region downstream from the pepM coding sequence contained extensive inverted repeats and was homologous to sequences found elsewhere in both Salmonella and other bacterial species.
Insights
Salmonella typhimurium pepM gene cloned, encoding methionine-specific aminopeptidase. A promoter mutation (pepM100) enhanced gene expression by increasing promoter homology.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- The pepM gene encodes methionine-specific aminopeptidase, an enzyme involved in protein processing.
- Understanding gene regulation is crucial for bacterial physiology and pathogenesis.
Purpose of the Study:
- To clone and sequence the pepM gene from Salmonella typhimurium.
- To investigate the molecular basis of increased pepM expression in a mutant allele.
Main Methods:
- Gene cloning and nucleotide sequencing.
- Sequence analysis and comparison with homologous genes (e.g., from Escherichia coli).
- Identification of promoter regions and regulatory elements.
Main Results:
- The pepM gene from S. typhimurium was cloned and sequenced, encoding a 264-amino acid protein homologous to its E. coli counterpart.
- An overproducer mutant allele (pepM100) exhibited a single base change in the promoter region, enhancing homology to the consensus promoter sequence.
- A downstream region contained inverted repeats, suggesting potential regulatory functions or involvement in gene expression modulation.
Conclusions:
- The study elucidated the genetic structure of the S. typhimurium pepM gene and its product.
- A specific promoter mutation was identified as responsible for increased pepM gene expression.
- The findings contribute to understanding bacterial gene regulation and potential mechanisms of sequence evolution.