Nitric oxide inhibits ornithine decarboxylase by S-nitrosylation.
Ornithine decarboxylase (ODC) is the initial enzyme in the polyamine synthetic pathway, and polyamines are required for cell proliferation. We have shown previously that nitric oxide (NO) inhibits ODC activity in Caco-2 cells and in crude cell lysate preparations. In this study we examined the mechanism by which NO inhibits the activity of purified ODC. NO, in the form of S-nitrosocysteine (CysNO), S-nitrosoglutathione (GSNO), or 1, 1-diethyl-2-hydroxy-2-nitroso-hydrazine (DEA/NO), inhibited enzyme activity in a concentration-dependent manner. CysNO (1 microM) inhibited ODC activity by approximately 90% and 3 microM GSNO by more than 70%. DEA/NO was less potent, inhibiting enzyme activity by 70% at a concentration of 30 microM. Inhibition of enzyme activity by CysNO, GSNO, or DEA/NO was reversible by addition of dithiothreitol or glutathione. Cuprous ion (Cu (I)) also reversed the inhibitory effect of these NO donor agents. The data presented here support the hypothesis that NO inhibits ODC activity via S-nitrosylation of a critical cysteine residue(s) on ODC.
Bauer
P M
PM
Department of Molecular and Medical Pharmacology, University of California-Los Angeles School of Medicine, Los Angeles, California, 90095-1735, USA.
Fukuto
J M
JM
Buga
G M
GM
Pegg
A E
AE
Ignarro
L J
LJ
D020134:Catalytic Domain; D003300:Copper / Q000494:pharmacology; D003545:Cysteine / Q000031:analogs & derivatives*; D009569:Nitric Oxide / Q000494:pharmacology*; D009603:Nitroso Compounds / Q000378:metabolism*; D009955:Ornithine Decarboxylase / Q000187:drug effects; D065108:Ornithine Decarboxylase Inhibitors; D010084:Oxidation-Reduction; D013438:Sulfhydryl Compounds
D009603:Nitroso Compounds; D065108:Ornithine Decarboxylase Inhibitors; D013438:Sulfhydryl Compounds; D009569:Nitric Oxide; D003300:Copper; D009955:Ornithine Decarboxylase; D003545:Cysteine