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Some properties of nicked Vibrio vulnificus hemolysin
S Miyoshi1, S Fujii, K Tomochika
1Faculty of Pharmaceutical Sciences, Okayama University, Tsushima-Naka, Okayama, 700, Japan.
Abstract:
Vibrio vulnificus, an opportunistic human pathogen, secretes the 50 kDa single-chain hemolysin. When incubated with an exocellular protease from this vibrio, the 50 kDa hemolysin was cleaved in some peptides joined with the disulfide bond(s); the 40 kDa fragment and the small fragment(s) undetectable in SDS-PAGE. The nicked hemolysin induced comparable hemolysis through the same process as that of the intact toxin. However, the nicked hemolysin was found to be more stable against inactivation due to autoaggregation, so that it formed a larger precipitation zone in the single radial immunodiffusion test using the antiserum against the intact hemolysin. These results suggest that V. vulnificus hemolysin is modified to be a more hydrophilic protein by nicking, while it is not accompanied by loss of the hemolytic activity.
Insights
Vibrio vulnificus hemolysin, when cleaved by a bacterial protease, remains hemolytic but becomes more stable. This modification enhances its resistance to autoaggregation, suggesting a potential role in pathogenesis.
Area of Science:
- Microbiology
- Pathogen Research
- Protein Biochemistry
Background:
- Vibrio vulnificus is an opportunistic pathogen.
- It secretes a 50 kDa single-chain hemolysin.
- Hemolysins are crucial virulence factors for many bacteria.
Purpose of the Study:
- To investigate the effect of proteolytic cleavage on V. vulnificus hemolysin activity and stability.
- To understand the structural modifications and functional consequences of hemolysin nicking.
Main Methods:
- Incubation of V. vulnificus hemolysin with an exocellular protease.
- Analysis of cleaved fragments using SDS-PAGE.
- Assay of hemolytic activity.
- Evaluation of stability using single radial immunodiffusion tests.
Main Results:
- Proteolytic cleavage yielded a 40 kDa fragment and smaller, undetectable fragments.
- The nicked hemolysin retained comparable hemolytic activity.
- Nicked hemolysin exhibited increased stability against autoaggregation.
- A larger precipitation zone was observed in immunodiffusion assays.
Conclusions:
- Proteolytic nicking modifies V. vulnificus hemolysin into a more hydrophilic form.
- This modification does not impair hemolytic activity.
- Enhanced stability suggests a potential role in V. vulnificus pathogenesis.