Nitric oxide generated from isoniazid activation by KatG: source of nitric oxide and activity against Mycobacterium tuberculosis.
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.
College of Pharmacy, Toxicology Program, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA. gtimmins@salud.unm.edu
Graham S
GS
Timmins
Sharon
S
Master
Frank
F
Rusnak
Vojo
V
Deretic
D000995:Antitubercular Agents / Q000378:metabolism / Q000494:pharmacology*; D001426:Bacterial Proteins; D001711:Biotransformation; D002374:Catalase / Q000378:metabolism; D016166:Free Radical Scavengers / Q000494:pharmacology; D007538:Isoniazid / Q000378:metabolism / Q000494:pharmacology*; D009163:Mycobacterium bovis / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009195:Peroxidase / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000378:metabolism; D011355:Prodrugs / Q000378:metabolism / Q000494:pharmacology; D019097:Spin Trapping; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D000995:Antitubercular Agents; D001426:Bacterial Proteins; D016166:Free Radical Scavengers; D011355:Prodrugs; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D010088:Oxidoreductases; D002374:Catalase; C480353:katG protein, Mycobacterium tuberculosis; D009195:Peroxidase; D007538:Isoniazid