Purification and Characterization of Dimethylsulfide Monooxygenase from Hyphomicrobium sulfonivorans

Boden, Rich, Borodina, Elena, Wood, Ann P., Kelly, Donovan P., Murrell, J. Colin and Schafer, Hendrik (2011) Purification and Characterization of Dimethylsulfide Monooxygenase from Hyphomicrobium sulfonivorans. Journal of Bacteriology, 193 (5). pp. 1250-1258. ISSN 0021-9193

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Abstract

Dimethylsulfide (DMS) is a volatile organosulfur compound which has been implicated in the biogeochemical cycling of sulfur and in climate control. Microbial degradation is a major sink for DMS. DMS metabolism in some bacteria involves its oxidation by a DMS monooxygenase in the first step of the degradation pathway; however, this enzyme has remained uncharacterized until now. We have purified a DMS monooxygenase from Hyphomicrobium sulfonivorans, which was previously isolated from garden soil. The enzyme is a member of the flavin-linked monooxygenases of the luciferase family and is most closely related to nitrilotriacetate monooxygenases. It consists of two subunits: DmoA, a 53-kDa FMNH2-dependent monooxygenase, and DmoB, a 19-kDa NAD(P)H-dependent flavin oxidoreductase. Enzyme kinetics were investigated with a range of substrates and inhibitors. The enzyme had a Km of 17.2 (± 0.48) µM for DMS (kcat = 5.45 s-1) and a Vmax of 1.25 (± 0.01) µmol NADH oxidized min-1 (mg protein-1). It was inhibited by umbelliferone, 8-anilinonaphthalenesulfonate, a range of metal-chelating agents, and Hg2+, Cd2+, and Pb2+ ions. The purified enzyme had no activity with the substrates of related enzymes, including alkanesulfonates, aldehydes, nitrilotriacetate, or dibenzothiophenesulfone. The gene encoding the 53-kDa enzyme subunit has been cloned and matched to the enzyme subunit by mass spectrometry. DMS monooxygenase represents a new class of FMNH2-dependent monooxygenases, based on its specificity for dimethylsulfide and the molecular phylogeny of its predicted amino acid sequence. The gene encoding the large subunit of DMS monooxygenase is colocated with genes encoding putative flavin reductases, homologues of enzymes of inorganic and organic sulfur compound metabolism, and enzymes involved in riboflavin synthesis.

Item Type: Article
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Users 2731 not found.
Date Deposited: 23 Jan 2012 16:28
Last Modified: 21 Apr 2020 16:38
URI: https://ueaeprints.uea.ac.uk/id/eprint/36371
DOI: 10.1128/JB.00977-10

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