Degradation of 2-hydro-1,2-dihydroxy benzoate (DHB) to catechol. (1R,6S)-1,6-dihydroxycyclohexa-2,4-diene-1-carboxylate + NAD(+) = catechol + CO2 + NADH Aromatic compound metabolism; benzoate degradation via hydroxylation; catechol from benzoate: step 2/2. Homodimer. Belongs to the short-chain dehydrogenases/reductases (SDR) family.