EC 1.14.14.22     
Accepted name: dibenzothiophene sulfone monooxygenase
Reaction: dibenzothiophene-5,5-dioxide + FMNH2 + NADH + O2 = 2′-hydroxybiphenyl-2-sulfinate + H2O + FMN + NAD+ + H+ (overall reaction)
(1a) dibenzothiophene-5,5-dioxide + FMNH2 + O2 = 2′-hydroxybiphenyl-2-sulfinate + FMN-N5-oxide
(1b) FMN-N5-oxide + NADH = FMN + H2O + NAD+ + H+ (spontaneous)
Glossary: dibenzothiophene-5,5-dioxide = dibenzothiophene sulfone
Other name(s): dszA (gene name)
Systematic name: dibenzothiophene-5,5-dioxide,FMNH2:oxygen oxidoreductase
Comments: This bacterial enzyme catalyses a step in the desulfurization pathway of dibenzothiophenes. The enzyme forms a two-component system with a dedicated NADH-dependent FMN reductase (EC 1.5.1.42) encoded by the dszD gene, which also interacts with EC 1.14.14.21, dibenzothiophene monooxygenase. The flavin-N5-oxide that is formed by the enzyme reacts spontaneously with NADH to give oxidized flavin, releasing a water molecule.
References:
1.  Gray, K.A., Pogrebinsky, O.S., Mrachko, G.T., Xi, L., Monticello, D.J. and Squires, C.H. Molecular mechanisms of biocatalytic desulfurization of fossil fuels. Nat. Biotechnol. 14 (1996) 1705–1709. [PMID: 9634856]
2.  Ohshiro, T., Kojima, T., Torii, K., Kawasoe, H. and Izumi, Y. Purification and characterization of dibenzothiophene (DBT) sulfone monooxygenase, an enzyme involved in DBT desulfurization, from Rhodococcus erythropolis D-1. J. Biosci. Bioeng. 88 (1999) 610–616. [PMID: 16232672]
3.  Konishi, J., Ishii, Y., Onaka, T., Ohta, Y., Suzuki, M. and Maruhashi, K. Purification and characterization of dibenzothiophene sulfone monooxygenase and FMN-dependent NADH oxidoreductase from the thermophilic bacterium Paenibacillus sp. strain A11-2. J. Biosci. Bioeng. 90 (2000) 607–613. [PMID: 16232919]
4.  Ohshiro, T., Ishii, Y., Matsubara, T., Ueda, K., Izumi, Y., Kino, K. and Kirimura, K. Dibenzothiophene desulfurizing enzymes from moderately thermophilic bacterium Bacillus subtilis WU-S2B: purification, characterization and overexpression. J. Biosci. Bioeng. 100 (2005) 266–273. [PMID: 16243275]
5.  Adak, S. and Begley, T.P. Dibenzothiophene catabolism proceeds via a flavin-N5-oxide intermediate. J. Am. Chem. Soc. 138 (2016) 6424–6426. [PMID: 27120486]
6.  Adak, S. and Begley, T.P. Flavin-N5-oxide: A new, catalytic motif in flavoenzymology. Arch. Biochem. Biophys. 632 (2017) 4–10. [PMID: 28784589]
[EC 1.14.14.22 created 2016, modified 2019]
 
 


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