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KatG from Salmonella typhimurium is a peroxynitritase
Samantha McLean1, Lesley A H Bowman, Robert K Poole
1Department of Molecular Biology and Biotechnology, The University of Sheffield, Western Bank, Sheffield, UK. S.McLean@sheffield.ac.uk
FEBS Letters
|March 24, 2010
Summary
Salmonella Typhimurium catalase-peroxidase (KatG) demonstrates peroxynitrite decomposition activity, suggesting a broader role in bacterial defense against oxidative stress beyond peroxide detoxification.
Area of Science:
- Microbiology
- Enzymology
- Bacterial Pathogenesis
Background:
- Pathogenic bacteria possess distinct defense mechanisms against oxidative and nitrosative stresses.
- Catalase-peroxidase (KatG) from Mycobacterium tuberculosis was recently found to have peroxynitritase activity.
- This suggests a potential overlap in bacterial stress response pathways.
Purpose of the Study:
- To investigate the peroxynitritase activity of catalase-peroxidase (KatG) from Salmonella Typhimurium.
- To characterize the enzyme's role in detoxifying reactive nitrogen species.
Main Methods:
- Cloning and purification of the katG gene from Salmonella Typhimurium.
- Biochemical characterization of the purified KatG enzyme.
- Assay of peroxynitrite decomposition rate and dihydrorhodamine oxidation reduction.
Main Results:
- Salmonella Typhimurium KatG exhibited significant peroxynitrite decomposition activity.
- A second-order rate constant of 4.2x10(4) M(-1)s(-1) was determined at pH 7.4 and 25°C.
- The enzyme reduced dihydrorhodamine oxidation by peroxynitrite by approximately 83%.
Conclusions:
- Salmonella Typhimurium KatG possesses peroxynitritase activity.
- This finding indicates a potentially broader role for KatG in bacterial oxidative stress defense.
- The enzyme contributes to the detoxification of peroxynitrite, a key damaging molecule.
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