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University of Plymouth PEARL https://pearl.plymouth.ac.uk Faculty of Science and Engineering School of Biological and Marine Sciences 2018-10-31 Bacterial Metabolism of C1 Sulfur Compounds Boden, R http://hdl.handle.net/10026.1/12734 Springer Nature Switzerland All content in PEARL is protected by copyright law. Author manuscripts are made available in accordance with publisher policies. Please cite only the published version using the details provided on the item record or document. In the absence of an open licence (e.g. Creative Commons), permissions for further reuse of content should be sought from the publisher or author. Bacterial Metabolism of C1 Sulfur Compounds Rich Boden and Lee P. Hutt Contents 1 Introduction and Overview ................................................................... 2 2 Handling, Quantifying, and Synthesizing C1 Organosulfur Compounds ................... 5 2.1 Quality, Storage, and Disposal ......................................................... 5 2.2 Determination of C1 Organosulfur Compounds in Cultures . ........................ 8 2.3 Isotopic Labeling for Ecological and Physiological Studies . .. .. .. .. .. .. .. .. .. .. 12 3 Pathways of C1 Organosulfur Compound Metabolism ...................................... 18 3.1 De Bont Pathway ....................................................................... 20 3.2 Visscher-Taylor Pathway ............................................................... 20 3.3 Smith-Kelly Pathway ................................................................... 21 3.4 De Zwart-Kuenen Pathway ............................................................. 22 3.5 Boden-Kelly Pathway .................................................................. 22 3.6 Padden-Wood Pathway ................................................................. 23 3.7 Borodina-Wood pathway ............................................................... 24 3.8 Kino-Wicht pathway .................................................................... 25 3.9 Koch-Dahl Pathway .................................................................... 25 4 Enzymology of C1 Organosulfur Compound Metabolism . ... ... ... ... ... ... ... .. ... ... ... 26 4.1 Dissimilatory Dimethylsulfide Monooxygenase (EC 1.14.13.131) .................. 27 4.2 Assimilatory Dimethylsulfide S-Monooxygenase (EC 1.8.1.x) ...................... 28 4.3 Dissimilatory Dimethylsulfide Demethylase (EC 2.1.1.x)........................... 29 4.4 Methanethiol Oxidase (EC 1.8.3.4) ................................................... 30 R. Boden (*) School of Biological and Marine Sciences, Faculty of Science and Engineering, University of Plymouth, Plymouth, UK Sustainable Earth Institute, Faculty of Science and Engineering, University of Plymouth, Plymouth, UK e-mail: [email protected] L. P. Hutt School of Biological and Marine Sciences, Faculty of Science and Engineering, University of Plymouth, Plymouth, UK e-mail: [email protected] # Springer Nature Switzerland AG 2019 1 F. Rojo (ed.), Aerobic Utilization of Hydrocarbons, Oils and Lipids, Handbook of Hydrocarbon and Lipid Microbiology, https://doi.org/10.1007/978-3-319-39782-5_9-1 2 R. Boden and L. P. Hutt 4.5 Methanethiol S-methyltransferase (EC 2.1.1.334) ................................... 31 4.6 Dimethylsulfide-Cytochrome c Reductase (EC 1.8.2.4) ... .. ... ... .. ... .. ... .. ... .. 31 4.7 Respiratory Dimethylsulfoxide Reductase (EC 1.8.5.3) .. .. .. .. ... .. .. .. .. ... .. .. .. 32 4.8 Dissimilatory Dimethylsulfoxide Reductase (EC 1.8.1.x)........................... 32 4.9 Dissimilatory Dimethylsulfone Reductase (EC 1.8.1.17) ............................ 33 4.10 Assimilatory Dimethylsulfone Monooxygenase (EC 1.14.14.35), Assimilatory Methanesulfonate Monooxygenase (EC 1.14.14.34), and Dissimilatory Methanesulfonate Monooxygenase (EC 1.14.13.111) . .. .. .. .. .. .. .. .. .. .. .. .. 33 4.11 Putative Dissimilatory Dimethylsulfide Hydrolase ................................... 35 5 Ecological Theory and Strategies ............................................................ 35 6 Research Needs ............................................................................... 37 References ........................................................................................ 37 Abstract The metabolism of C1 organosulfur compounds by the Bacteria is important in the biogeochemical cycling of sulfur and carbon and in climate regulation in terms of mediating release of, e.g., dimethylsulfide from the oceans. Herein we review the canon of work on the metabolism of dimethylsulfide, dimethylsulfoxide, dimethylsulfone, methanesulfonate, dimethyldisulfide, and methanethiol, in terms of dissimilation to formaldehyde or carbon dioxide when used as carbon and energy sources by methylotrophs or autotrophs, oxidation to sulfite prior to assimilation as sulfur sources, and use as respiratory terminal electron acceptors. We discuss the enzymology of the metabolism of these compounds and propose a revision to the Enzyme Commission classification to some of them where multiple enzymes are clearly grouped under one name at present. We also provide methodologies for enzyme assays, for the safe handling and quantification of these compounds, and for the synthesis of carbon-14, carbon-11, sulfur-34, and sulfur- 34 compounds for use in physiological and ecological studies. 1 Introduction and Overview The diversity of one-carbon (C1) compounds containing sulfur is given in Table 1, including both organic and inorganic examples, and the abbreviations for them used in this chapter. The bacterial metabolism of C1 organosulfur compounds is largely limited in understanding to methanethiol (MT), dimethylsulfide (DMS), dimethylsulfoxide (DMSO), dimethylsulfone (DMSO2), methanesulfonate (MSA), and dimethyldisulfide (DMDS), but as Table 1 shows, there is considerable scope for broadening our understanding with many unstudied compounds with regard to microbiology. The roles, sources, sinks, and chemistry of the C1 organosulfur compounds in the environment (atmospheric chemistry, etc.) are touched on in this chapter where important, but for good reviews on core aspects of the subject, the reader should consult Kelly (1996), Keine (1993, 1996), Wood (1996), and Kelly et al. (1993) for short reviews and perspectives that, while over 20 years old, are very useful – for a longer and more up-to-date review on the subject, Schäfer et al. (2010) give much Bacterial Metabolism of C1 Sulfur Compounds 3 Table 1 Diversity and properties of one-carbon (C1) sulfur compounds, defined by their absence of carbon-carbon bonds Compound and abbreviation Melting point (C) Boiling point (C) Formula Organic Methanethiol (MT) À123 +6 CH3SH a Methanethial (CH2S) N.D. N.D.CH2S 1,2,3-trithiane (Thioform) 215 230 (CH2)3S3 Dimethylsulfide (DMS) À98 +35 (CH3)2S Dimethylsulfoxide (DMSO) +19 +189 (CH3)2SO Dimethylsulfone (DMSO2) +109 +248 (CH3)2SO2 Dimethylsulfide (DMDS) À85 +110 (CH3)2S2 Dimethyltrisulfide (DMTS) À68 +170 (CH3)2S3 Dimethyltetrasulfide (DMQS) N.D. +243 (CH3)2S4 Dimethylsulfite (DSMO3) N.D. +126 (CH3O)2SO Dimethylsulfate (DMSO4) À32 +188 (CH3O)2SO2 Lenthionine +60 N.D. (CH2)2S5 1,4,2-dithiazole-5-thione +78 +280 CHNSCSS 1,3,4-oxathiazol-2-one +36 +226 CHNSCOO b À Methanesulfonate (MSA) ––CH3SO3 b À Methanesulfinate (MSiA) ––CH3SO2 Methylmethanesulfonate (MMSA) +20 +202 CH3SO3CH3 Thiourea +182 C(NH2)2S Inorganic Carbon disulfide (CS2) À112 +46 CS2 Carbon monosulfide (CS) N.D. N.D.CS Carbonyl sulfide (COS) À139 À50 COS b 2À Thiocarbonate (TC) ––CO2S aSpontaneously oligomerizes into 1,3,5-trithiane bUsed in the form of the sodium or potassium salts, which are currently both commercially available for both MSA and MSiA more depth. Obviously, the reader is directed to Charlson et al. (1987) for the overarching significance of these compounds in the environment, particularly DMS. In this chapter, we cover the physiological pathways of C1 organosulfur com- pound metabolism, as well as give detail on each enzyme involved and the structure, function, ecology, and evolution thereof. Since the assay methods for these enzymes have not been curated in any other text, we have included them for completeness. We also give consideration to the practicalities and safety of working with C1 organosulfur compounds, as well as methods for their determination in the micro- biology laboratory and methods for the synthesis of stable (carbon-13, sulfur-34) and radiolabeled (carbon-11, carbon-14, sulfur-35) compounds for use in physiological and ecological studies – this is particularly important since some of the key questions and gaps in our understanding can (at present) only be resolved using such meth- odologies and these labeled compounds are not commercially available, or, where they are, it is for >£20,000 (US$26,500, €23,000) as a custom synthesis, which 4 R. Boden and L. P. Hutt prohibits work for many laboratories. Since these methods are not especially com- plex, we have included them with hopefully enough detail for the non-chemist to reproduce them without too much difficulty! The oxidation of C1 organosulfur compounds to sulfate or partially to other C1 organosulfur species is well known in methylotrophic and heterotrophic Bacteria, respectively. For illustration of the bioenergetics of these oxidations, those of dimethylsulfide (DMS), dimethylsulfoxide (DMSO), dimethylsulfone (DMSO2), methanethiol (MT), and dimethyldisulfide (DMDS) to sulfate and carbon dioxide are given, along with the oxidation of DMS to DMSO found in heterotrophs