Abstract
Isonicotinic acid hydrazide (INH) is a frontline antituberculosis agent. Once taken up by Mycobacterium tuberculosis, INH requires activation by the catalase-peroxidase KatG, converting INH from its prodrug form into a range of bactericidal reactive species. Here we used 15N-labeled INH together with electron paramagnetic resonance spin trapping techniques to demonstrate that nitric oxide (NO*) is generated from oxidation at the hydrazide nitrogens during the activation of INH by M. tuberculosis KatG. We also observed that a specific scavenger of NO* provided protection against the antimycobacterial activity of INH in bacterial culture. No significant increases in mycobacterial protein nitration were detected, suggesting that NOdot; and not peroxynitrite, a nitrating metabolite of NO*, is involved in antimycobacterial action. In conclusion, INH-derived NO* has biological activity, which directly contributes to the antimycobacterial action of INH.
Publication types
-
Research Support, U.S. Gov't, P.H.S.
MeSH terms
-
Antitubercular Agents / metabolism
-
Antitubercular Agents / pharmacology*
-
Bacterial Proteins*
-
Biotransformation
-
Catalase / metabolism
-
Free Radical Scavengers / pharmacology
-
Isoniazid / metabolism
-
Isoniazid / pharmacology*
-
Mycobacterium bovis / metabolism
-
Mycobacterium tuberculosis / drug effects*
-
Mycobacterium tuberculosis / genetics
-
Mycobacterium tuberculosis / metabolism
-
Nitric Oxide / metabolism*
-
Oxidoreductases / genetics
-
Oxidoreductases / metabolism
-
Oxidoreductases / physiology*
-
Peroxidase / metabolism
-
Peroxynitrous Acid / metabolism
-
Prodrugs / metabolism
-
Prodrugs / pharmacology
-
Spin Trapping
-
Tyrosine / analogs & derivatives*
-
Tyrosine / metabolism
Substances
-
Antitubercular Agents
-
Bacterial Proteins
-
Free Radical Scavengers
-
Prodrugs
-
Peroxynitrous Acid
-
Nitric Oxide
-
3-nitrotyrosine
-
Tyrosine
-
Oxidoreductases
-
Catalase
-
katG protein, Mycobacterium tuberculosis
-
Peroxidase
-
Isoniazid