Involved in the gamma-resorcylate (2,6-dihydroxybenzoate) catabolism (PubMed:15466039). Catalyzes the reversible decarboxylation of gamma-resorcylate to resorcinol (PubMed:15466039). The reaction is reversible, but equilibrium greatly favors the decarboxylation reaction (PubMed:15466039). Also catalyzes the decarboxylation of 2,3-dihydroxybenzoate to catechol, but does not act on 2,4-dihydroxybenzoate, 2,5-dihydroxybenzoate, 3,4-dihydroxybenzoate, 3,5-dihydroxybenzoate, 2-hydroxybenzoate, or 3-hydroxybenzoate. Only resorcinol is carboxylated by the reverse reaction (PubMed:15466039). 2,6-dihydroxybenzoate + H(+) = CO2 + resorcinol 2,3-dihydroxybenzoate + H(+) = catechol + CO2 Binds 1 Zn(2+) ion per subunit. Inhibited by CuCl(2), monoiodoacetate and diethylpyrocarbonate (PubMed:15466039). Inhibited by 2,3-dihydroxybenzaldehyde, which is an analog of the substrate 2,3-dihydroxybenzoate (PubMed:16963440). Optimum pH is 8.0 for decarboxylation. Optimum pH is 7.0 for carboxylation. Optimum temperature is 70 degrees Celsius. Aromatic compound metabolism. Homotetramer (PubMed:15466039, PubMed:16963440). Dimer of dimers (PubMed:16963440). Induced in the presence of gamma-resorcylate. Belongs to the metallo-dependent hydrolases superfamily. ACMSD family.