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Methylation of the flagellin of Salmonella typhimurium
Abstract:
The methylation of endogenous proteins by Salmonella typhimurium SL 870 was investigated in cell-free extracts by using S-adenosylmethionine as methyl donor. Several lines of evidence are presented which suggest that one of the methylated products is the protein flagellin. Mutant strains of SL 870 (nml(-)fla(+) and nml(+)fla(-)) were also found to synthesize epsilon-N-methyl-lysine. It is proposed that S. typhimurium possesses at least two genes specifying different methylating enzymes. One gene product is a flagellin-specific methylating enzyme, whereas the other gene(s) codes for enzymes that methylate one or more other cell proteins.
Insights
Salmonella typhimurium methylates its own proteins, including flagellin, using specific enzymes. Mutants reveal distinct methylation pathways, suggesting multiple genes control these processes in the bacteria.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Pathogenesis
Background:
- Salmonella typhimurium is a significant bacterial pathogen.
- Protein methylation is a crucial post-translational modification in bacteria.
- Understanding bacterial methylation mechanisms is vital for developing targeted interventions.
Purpose of the Study:
- To investigate the methylation of endogenous proteins by Salmonella typhimurium.
- To identify specific methylated proteins and the enzymes involved.
- To elucidate the genetic basis of protein methylation in S. typhimurium.
Main Methods:
- Utilized cell-free extracts of S. typhimurium SL 870.
- Employed S-adenosylmethionine as the methyl donor.
- Analyzed mutant strains (nml(-)fla(+) and nml(+)fla(-)) to differentiate methylation pathways.
Main Results:
- Identified flagellin as a methylated protein product.
- Detected epsilon-N-methyl-lysine in mutant strains.
- Provided evidence for at least two distinct methylating enzymes encoded by S. typhimurium genes.
Conclusions:
- S. typhimurium possesses specific enzymes for flagellin methylation.
- Additional enzymes methylate other cellular proteins, indicating complex regulation.
- The study proposes a genetic model for bacterial protein methylation.