Nitronate monooxygenase that uses molecular oxygen to catalyze the oxidative denitrification of alkyl nitronates. The toxin propionate 3-nitronate (P3N) is the best substrate (and the presumed physiological substrate), but this enzyme is also active on other primary and secondary nitronates such as propyl-1-nitronate, ethylnitronate, pentyl-1-nitronate, butyl-1-nitronate and propyl-2-nitronate (PubMed:25002579). Is likely involved in the degradation of P3N, that allows P.aeruginosa PAO1 to grow on 3-nitropropionate/P3N as the sole nitrogen source (PubMed:20382807). Also functions in the detoxification of P3N, a metabolic poison produced by plants and fungi as a defense mechanism (PubMed:25384477). Cannot oxidize nitroalkanes such as 3-nitropropionate, nitroethane, 1-nitropropane, 1-nitrobutane, 1-nitropentane, or 2-nitropropane (PubMed:25002579). H2O + 3 O2 + 3 propionate 3-nitronate = 3 3-oxopropanoate + 3 H(+) + H2O2 + 2 nitrate + nitrite Binds 1 FMN per subunit. kcat is 1300 sec(-1) with propionate 3-nitronate as substrate. kcat is 350 sec(-1) with ethylnitronate as substrate. kcat is 1120 sec(-1) with propyl-1-nitronate as substrate (at pH 7.5 and 30 degrees Celsius). Expression is repressed by NmoR. Is cotranscribed with ddlA. Deletion of this gene results in an increased sensitivity of the cells to P3N. At physiological pH, 3-nitropropionate (3-NPA) exists in equilibrium with its conjugate base, propionate-3-nitronate (P3N). P3N is a potent irreversible inhibitor of the key enzyme succinate dehydrogenase in the Krebs cycle and electron transport chain. P3N has been shown to be a toxic metabolite to bacteria, plants, fungi, mammals or any organism that uses succinate dehydrogenase. Belongs to the nitronate monooxygenase family. NMO class I subfamily.