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Methylsulfonomas methylovora M2 is a novel gram-negative methylotrophic bacterium that can grow on methanesulfonic acid (MSA) as the only source of carbon and energy. Oxidation by this bacterium was performed by a multicomponent MSA monooxygenase (MSAMO). Cloning and sequencing of a 7.5-kbp SphI fragment of chromosomal DNA showed four tightly connected genes encoding this unique monooxygenase. Analysis of the deduced MSAMO polypeptide sequences revealed that the enzyme has a two-component hdyroxylase of the mononuclear-iron-center type.

The component C of methanesulfonic acid monooxygenase (MSAMO) which mediated electron transfer reactions was purified and analyzed to characterize the biodegradation of MSA by the M2 methylotrophic strain. Analysis of the purified component C of MSAMO indicated the presence of two subunits and an iron-sulfur center. The gene encoding the component C of the MSAMO complex also exhibited protein sequence similarity to other ferredoxins conatining a Rieske [2Fe-2S] cluster.

Methylosinus trichosporium OB3b (for 'oddball' strain 3b) is an obligate aerobic methane-oxidizing alpha-proteobacterium that was originally isolated in 1970 by Roger Whittenbury and colleagues. This strain has since been used extensively to elucidate the structure and function of several key enzymes of methane oxidation, including both particulate and soluble methane monooxygenase (sMMO) and the extracellular copper chelator methanobactin. In particular, the catalytic properties of soluble methane monooxygenase from M. trichosporium OB3b have been well characterized in context with biodegradation of recalcitrant hydrocarbons, such as trichloroethylene. The sequence of the M. trichosporium OB3b genome is the first reported from a member of the Methylocystaceae family in the order Rhizobiales. doi: 10.1128/JB.01144-10

Beijerinckia indica subsp, indica is an aerobic, acidophilic, exopolysaccharide-producing, [N.sub.2]-fixing soil bacterium. It is a generalist chemoorganotroph that is phylogenetically closely related to facultative and obligate methanotrophs of the genera Methylocella and Methylocapsa. Here we report the full genome sequence of this bacterium. doi: 10.1128/JB.00656-10

Methylocella silvestris BL2 is an aerobic methanotroph originally isolated from an acidic forest soil in Germany. It is the first fully authenticated facultative methanotroph. It grows not only on methane and other one-carbon ([C.sub.1]) substrates, but also on some compounds containing carbon-carbon bonds, such as acetate, pyruvate, propane, and succinate. Here we report the full genome sequence of this bacterium. doi: 10.1128/JB.00506-10

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 purifed 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. [ABSTRACT FROM AUTHOR]

Methylocella silvestris BL2 is an aerobic methanotroph originally isolated from an acidic forest soil in Germany. It is the first fully authenticated facultative methanotroph. It grows not only on methane and other one-carbon (C1) substrates, but also on some compounds containing carbon-carbon bonds, such as acetate, pyruvate, propane, and succinate. Here we report the full genome sequence of this bacterium. [ABSTRACT FROM AUTHOR]