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Periplasmic superoxide dismutase in meningococcal pathogenicity
K E Wilks1, K L Dunn, J L Farrant
1Department of Paediatrics, Imperial College, School of Medicine at St. Mary's Hospital, London, United Kingdom.
Infection and Immunity
|January 10, 1998
Summary
Neisseria meningitidis superoxide dismutase C (sodC) protects against host-derived toxic oxygen radicals. A sodC mutant demonstrated reduced virulence in a mouse model, indicating Cu,Zn SOD contributes to meningococcal pathogenicity.
Area of Science:
- Microbiology
- Biochemistry
- Pathogenesis
Background:
- Meningococcal sodC encodes a periplasmic copper- and zinc-cofactored superoxide dismutase (Cu,Zn SOD).
- Cu,Zn SOD detoxifies superoxide radicals, preventing harmful downstream reactions.
- Its periplasmic location suggests a role in defending against extracellular microbicidal oxygen free radicals from host defenses.
Purpose of the Study:
- To investigate the role of meningococcal Cu,Zn SOD in pathogenicity.
- To determine if Cu,Zn SOD protects against exogenous superoxide radicals.
Main Methods:
- Construction of a sodC mutant using allelic exchange.
- Comparative growth and survival assays of wild-type and mutant meningococci in aerobic liquid culture.
- Sensitivity testing against intracellular (paraquat) and extracellular (xanthine/xanthine oxidase) superoxide generators.
- Virulence assessment in a mouse intraperitoneal infection model.
Main Results:
- Wild-type and mutant meningococci exhibited similar growth rates and aerobic survival.
- The sodC mutant showed no increased sensitivity to paraquat but was 1,000-fold more sensitive to extracellularly generated superoxide.
- The sodC mutant was significantly less virulent in the mouse infection model.
Conclusions:
- Meningococcal Cu,Zn SOD plays a crucial role in protecting against exogenous superoxide.
- Periplasmic Cu,Zn SOD contributes to the virulence of Neisseria meningitidis.
- This likely occurs by neutralizing toxic oxygen species produced by host defenses.