Accepted name: resorcinol 4-hydroxylase (FADH2)
Reaction: resorcinol + FADH2 + O2 = hydroxyquinol + FAD + H2O
Glossary: resorcinol = benzene-1,3-diol
hydroxyquinol = benzene-1,2,4-triol
Other name(s): graA (gene name)
Systematic name: resorcinol,FADH2:oxygen oxidoreductase (4-hydroxylating)
Comments: The enzyme, characterized from the bacterium Rhizobium sp. strain MTP-10005, uses FADH2 as a substrate rather than a cofactor. FADH2 is provided by a dedicated EC, flavin reductase (NADH). The enzyme participates in the degradation of γ-resorcylate and resorcinol. cf. EC, resorcinol 4-hydroxylase (NADH), and EC, resorcinol 4-hydroxylase (NADPH).
1.  Ohta, Y. and Ribbons, D.W. Bacterial metabolism of resorcinylic compounds: purification and properties of orcinol hydroxylase and resorcinol hydroxylase from Pseudomonas putida ORC. Eur. J. Biochem. 61 (1976) 259–269. [PMID: 1280]
2.  Yoshida, M., Oikawa, T., Obata, H., Abe, K., Mihara, H. and Esaki, N. Biochemical and genetic analysis of the γ-resorcylate (2,6-dihydroxybenzoate) catabolic pathway in Rhizobium sp. strain MTP-10005: identification and functional analysis of its gene cluster. J. Bacteriol. 189 (2007) 1573–1581. [PMID: 17158677]
[EC created 2016]
Accepted name: salicylate decarboxylase
Reaction: salicylate = phenol + CO2
Other name(s): salicylic acid decarboxylase; Scd
Systematic name: salicylate carboxy-lyase
Comments: In the reverse direction the enzyme catalyses the regioselective carboxylation of phenol into stoichiometric amounts of salicylate. The enzyme also catalyses the reversible decarboxylation of 2,4-dihydroxybenzoate, 2,6-dihydroxybenzoate, 2,3-dihydroxybenzoate and 4-aminosalicylate [1].
1.  Kirimura, K., Gunji, H., Wakayama, R., Hattori, T. and Ishii, Y. Enzymatic Kolbe-Schmitt reaction to form salicylic acid from phenol: enzymatic characterization and gene identification of a novel enzyme, Trichosporon moniliiforme salicylic acid decarboxylase. Biochem. Biophys. Res. Commun. 394 (2010) 279–284. [PMID: 20188702]
[EC created 2011]
Accepted name: γ-resorcylate decarboxylase
Reaction: 2,6-dihydroxybenzoate = 1,3-dihydroxybenzene + CO2
Glossary: 2,6-dihydroxybenzoate = γ-resorcylate
1,3-dihydroxybenzene = resorcinol
Other name(s): graF (gene name); tsdA (gene name)
Systematic name: 2,6-dihydroxybenzoate carboxy-lyase
Comments: The enzyme, characterized from several bacterial strains, is involved in the degradation of γ-resorcylate. It contains a zinc ion and a water molecule at the active site. The reaction is reversible, but equilibrium greatly favors the decarboxylation reaction.
1.  Yoshida, M., Fukuhara, N. and Oikawa, T. Thermophilic, reversible γ-resorcylate decarboxylase from Rhizobium sp. strain MTP-10005: purification, molecular characterization, and expression. J. Bacteriol. 186 (2004) 6855–6863. [PMID: 15466039]
2.  Ishii, Y., Narimatsu, Y., Iwasaki, Y., Arai, N., Kino, K. and Kirimura, K. Reversible and nonoxidative γ-resorcylic acid decarboxylase: characterization and gene cloning of a novel enzyme catalyzing carboxylation of resorcinol, 1,3-dihydroxybenzene, from Rhizobium radiobacter. Biochem. Biophys. Res. Commun. 324 (2004) 611–620. [PMID: 15474471]
3.  Matsui, T., Yoshida, T., Yoshimura, T. and Nagasawa, T. Regioselective carboxylation of 1,3-dihydroxybenzene by 2,6-dihydroxybenzoate decarboxylase of Pandoraea sp. 12B-2. Appl. Microbiol. Biotechnol. 73 (2006) 95–102. [PMID: 16683134]
4.  Goto, M., Hayashi, H., Miyahara, I., Hirotsu, K., Yoshida, M. and Oikawa, T. Crystal structures of nonoxidative zinc-dependent 2,6-dihydroxybenzoate (γ-resorcylate) decarboxylase from Rhizobium sp. strain MTP-10005. J. Biol. Chem. 281 (2006) 34365–34373. [PMID: 16963440]
5.  Kasai, D., Araki, N., Motoi, K., Yoshikawa, S., Iino, T., Imai, S., Masai, E. and Fukuda, M. γ-Resorcylate catabolic-pathway genes in the soil actinomycete Rhodococcus jostii RHA1. Appl. Environ. Microbiol. 81 (2015) 7656–7665. [PMID: 26319878]
[EC created 2016]