Mycobacterium tuberculosis alkylhydroperoxidase C (AhpC) belongs to the peroxiredoxin family, but unusually contains three cysteine residues in its active site. It is overexpressed in isoniazid-resistant strains of M. tuberculosis. We demonstrate that AhpC is capable of acting as a general antioxidant by protecting a range of substrates including supercoiled DNA. Active-site Cys to Ala mutants show that all three cysteine residues are important for activity. Cys-61 plays a central role in activity and Cys-174 also appears to be crucial. Interestingly, the C174A mutant is inactive, but double mutant C174/176A shows significant revertant activity. Kinetic parameters indicate that the C176A mutant is active, although much less efficient. We suggest that M. tuberculosis AhpC therefore belongs to a novel peroxiredoxin family and might follow a unique disulphide-relay reaction mechanism.
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October 2002
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Research Article|
October 01 2002
Site-directed mutagenesis reveals a novel catalytic mechanism of Mycobacterium tuberculosis alkylhydroperoxidase C Available to Purchase
Radha CHAUHAN;
Radha CHAUHAN
∗Institute of Microbial Technology, Sector 39-A, Chandigarh 160036, India,
†Centre for DNA Fingerprinting and Diagnostics, ECIL Road, Nacharam, Hyderabad 500076, India
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Shekhar C. MANDE
Shekhar C. MANDE
1
†Centre for DNA Fingerprinting and Diagnostics, ECIL Road, Nacharam, Hyderabad 500076, India
1To whom correspondence should be addressed (e-mail [email protected]).
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Publisher: Portland Press Ltd
Received:
April 05 2002
Revision Received:
June 10 2002
Accepted:
June 25 2002
Accepted Manuscript online:
June 25 2002
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London ©2002
2002
Biochem J (2002) 367 (1): 255–261.
Article history
Received:
April 05 2002
Revision Received:
June 10 2002
Accepted:
June 25 2002
Accepted Manuscript online:
June 25 2002
Citation
Radha CHAUHAN, Shekhar C. MANDE; Site-directed mutagenesis reveals a novel catalytic mechanism of Mycobacterium tuberculosis alkylhydroperoxidase C. Biochem J 1 October 2002; 367 (1): 255–261. doi: https://doi.org/10.1042/bj20020545
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