EC 1.14.13.111     
Accepted name: methanesulfonate monooxygenase (NADH)
Reaction: methanesulfonate + NADH + H+ + O2 = formaldehyde + NAD+ + sulfite + H2O
Glossary: methanesulfonate = CH3-SO3-
formaldehyde = H-CHO
Other name(s): mesylate monooxygenase; mesylate,reduced-FMN:oxygen oxidoreductase; MsmABC; methanesulfonic acid monooxygenase; MSA monooxygenase; MSAMO
Systematic name: methanesulfonate,NADH:oxygen oxidoreductase
Comments: A flavoprotein. Methanesulfonate is the simplest of the sulfonates and is a substrate for the growth of certain methylotrophic microorganisms. Compared with EC 1.14.14.5, alkanesulfonate monooxygenase, this enzyme has a restricted substrate range that includes only the short-chain aliphatic sulfonates (methanesulfonate to butanesulfonate) and excludes all larger molecules, such as arylsulfonates [1]. The enzyme from the bacterium Methylosulfonomonas methylovora is a multicomponent system comprising a hydroxylase, a reductase (MsmD) and a ferredoxin (MsmC). The hydroxylase has both large (MsmA) and small (MsmB) subunits, with each large subunit containing a Rieske-type [2Fe-2S] cluster. cf. EC 1.14.14.34, methanesulfonate monooxygenase (FMNH2).
References:
1.  de Marco, P., Moradas-Ferreira, P., Higgins, T.P., McDonald, I., Kenna, E.M. and Murrell, J.C. Molecular analysis of a novel methanesulfonic acid monooxygenase from the methylotroph Methylosulfonomonas methylovora. J. Bacteriol. 181 (1999) 2244–2251. [PMID: 10094704]
2.  Higgins, T.P., Davey, M., Trickett, J., Kelly, D.P. and Murrell, J.C. Metabolism of methanesulfonic acid involves a multicomponent monooxygenase enzyme. Microbiology 142 (1996) 251–260. [PMID: 8932698]
[EC 1.14.13.111 created 2009 as EC 1.14.14.6, transferred 2010 to EC 1.14.13.111, modified 2016]
 
 
EC 1.14.14.6      
Transferred entry: methanesulfonate monooxygenase. Now EC 1.14.13.111, methanesulfonate monooxygenase. Formerly thought to involve FMNH2 but now shown to use NADH.
[EC 1.14.14.6 created 2009, deleted 2010]
 
 
EC 1.14.14.34     
Accepted name: methanesulfonate monooxygenase (FMNH2)
Reaction: methanesulfonate + FMNH2 + O2 = formaldehyde + FMN + sulfite + H2O
Glossary: methanesulfonate = CH3-SO3-
formaldehyde = H-CHO
Other name(s): msuD (gene name); ssuD (gene name)
Systematic name: methanesulfonate,FMNH2:oxygen oxidoreductase
Comments: The enzyme, characterized from Pseudomonas strains, allows the organisms to utilize methanesulfonate as their sulfur source. It acts in combination with a dedicated NADH-dependent FMN reductase (EC 1.5.1.42), which provides it with reduced FMN. cf. EC 1.14.13.111, methanesulfonate monooxygenase (NADH).
References:
1.  Kertesz, M.A., Schmidt-Larbig, K. and Wuest, T. A novel reduced flavin mononucleotide-dependent methanesulfonate sulfonatase encoded by the sulfur-regulated msu operon of Pseudomonas aeruginosa. J. Bacteriol. 181 (1999) 1464–1473. [PMID: 10049377]
2.  Endoh, T., Kasuga, K., Horinouchi, M., Yoshida, T., Habe, H., Nojiri, H. and Omori, T. Characterization and identification of genes essential for dimethyl sulfide utilization in Pseudomonas putida strain DS1. Appl. Microbiol. Biotechnol. 62 (2003) 83–91. [PMID: 12835925]
[EC 1.14.14.34 created 2016]
 
 
EC 1.14.14.35     
Accepted name: dimethylsulfone monooxygenase
Reaction: dimethyl sulfone + FMNH2 + O2 = methanesulfinate + formaldehyde + FMN + H2O
Other name(s): sfnG (gene name)
Systematic name: dimethyl sulfone,FMNH2:oxygen oxidoreductase
Comments: The enzyme, characterized from Pseudomonas spp., is involved in a dimethyl sulfide degradation pathway. It is dependent on NAD(P)H-dependent FMN reductase (EC 1.5.1.38, EC 1.5.1.39, or EC 1.5.1.42), which provides it with reduced FMN. The product, methanesulfinate, is oxidized spontaneously to methanesulfonate in the presence of dioxygen and FMNH2.
References:
1.  Endoh, T., Habe, H., Nojiri, H., Yamane, H. and Omori, T. The σ54-dependent transcriptional activator SfnR regulates the expression of the Pseudomonas putida sfnFG operon responsible for dimethyl sulphone utilization. Mol. Microbiol. 55 (2005) 897–911. [PMID: 15661012]
2.  Wicht, D.K. The reduced flavin-dependent monooxygenase SfnG converts dimethylsulfone to methanesulfinate. Arch. Biochem. Biophys. 604 (2016) 159–166. [PMID: 27392454]
[EC 1.14.14.35 created 2016]