Related Experiment Videos
The hemolytic effect of Salmonella typhi Ty 2 porins
Abstract:
Two outer membrane proteins of Salmonella typhi Ty 2 were extensively co-purified. According to their migration in dodecylsulfate/polyacrylamide gel electrophoresis and solubility characteristics, these proteins are homologous to the 35-kDa and 36-kDa porins found in Salmonella typhimurium. A porin homologous to the 34-kDa one has not been found in S. typhi Ty 2. A critical step in the purification of porins is heating at 100 degrees C in 2% sodium dodecyl sulfate before Sephadex gel filtration. The absence of detergent in aqueous suspensions enhances porin aggregation, these aggregations inducing human red cell lysis. Porins obtained by an alternative procedure consisting of heating at 60 degrees C instead of 100 degrees C were also hemolytic. Using nanomolar concentration of porins a strong influence of temperature on the hemolytic effect was observed. Porin-induced hemolysis was inhibited with anti-porin serum, as well as by a treatment with phenylglyoxal, which reacts with the arginine residues of proteins. The membrane-disrupting ability of porins aggregates might explain some pathogenic characteristics of gram-negative bacterial infections.
Insights
Salmonella typhi porins, similar to those in Salmonella typhimurium, were purified and found to cause red blood cell lysis. Temperature significantly influences this hemolytic effect, which can be inhibited by specific serum or chemical treatment.
Area of Science:
- Microbiology
- Protein biochemistry
- Immunology
Background:
- Salmonella typhi is a significant human pathogen.
- Outer membrane proteins, specifically porins, play crucial roles in bacterial pathogenesis.
- Understanding Salmonella porins is key to developing novel therapeutic strategies.
Purpose of the Study:
- To extensively co-purify outer membrane proteins from Salmonella typhi Ty 2.
- To characterize the identified porins and compare them to those found in Salmonella typhimurium.
- To investigate the hemolytic activity of purified Salmonella typhi porins and factors influencing it.
Main Methods:
- Co-purification of outer membrane proteins from Salmonella typhi Ty 2.
- Dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) for protein analysis.
- Sephadex gel filtration for purification.
- Hemolysis assays to assess red blood cell lysis.
- Inhibition assays using anti-porin serum and phenylglyoxal.
Main Results:
- Two porins homologous to 35-kDa and 36-kDa porins of Salmonella typhimurium were identified in Salmonella typhi Ty 2.
- A porin homologous to the 34-kDa porin of Salmonella typhimurium was not found in Salmonella typhi Ty 2.
- Purified porins, especially when aggregated in the absence of detergent, induced significant red blood cell lysis (hemolysis).
- Hemolytic activity was temperature-dependent and could be inhibited by anti-porin serum and phenylglyoxal treatment.
Conclusions:
- Salmonella typhi Ty 2 possesses porins homologous to those in Salmonella typhimurium, with potential implications for pathogenicity.
- Porin aggregation and temperature are critical factors in the membrane-disrupting and hemolytic activity of these proteins.
- The membrane-disrupting ability of porin aggregates may contribute to the pathogenesis of gram-negative bacterial infections.