6-hydroxy-3-succinoylpyridine 3-monooxygenase (, 6-hydroxy-3-succinoylpyridine hydroxylase, hspA (gene), hspB (gene)) is an enzyme with systematic name 4-(6-hydroxypyridin-3-yl)-4-oxobutanoate,NADH:oxygen oxidoreductase (3-hydroxylating, succinate semialdehyde releasing). This enzyme catalyses the following chemical reaction
The four substrates of this enzyme are 6-hydroxy-3-succinoylpyridine, reduced nicotinamide adenine dinucleotide (NADH), oxygen, and two protons. Its products are 2,5-dihydroxypyridine, oxidised NAD<sup>+</sup>, water, and succinic semialdehyde. It catalyses a reaction in the nicotine degradation pathway of Pseudomonas species.