Occurrence and biosynthesis of 3-mercaptopropionic acid in<i>Methanocaldococcus jannaschii</i>

The anaerobic oxidation of methane (AOM) mitigates the flux of methane from marine sediments into the water column. AOM is performed by anaerobic methanotrophic archaea (ANME) that reverse the methanogenesis pathway and partner bacteria that utilize the released reducing equivalents for sulfate reduction. Here, we investigated small-molecule extracts from sediment-free thermophilic enrichment cultures of ANME-1 and sulfate-reducing bacteria using ultraperformance liquid chromatography with high-resolution mass spectrometry. During the analysis, we discovered a novel thioquinoxalinol-containing redox molecule as a major component of the chemically derivatized small-molecule pool. This compound contains both a redox active quinoxaline heterocyclic ring and a thiol group. Additionally, the same core structure was identified that contains a sulfate ester on the hydroxyl group, which likely makes the molecule more water soluble. Hydrated versions of both structures were also observed as major compounds in the extracts. On the basis of reactions of model compounds such as quinoxalin-6-ol, the hydrated version appears to be formed from the addition of water to the dehydropyrazine ring followed by an oxidation. These thioquinoxalinol compounds, which represent completely new structures in biochemistry, may be involved in electron transport processes within and/or between ANME-1 and sulfate-reducing bacteria, may serve protective roles by reacting with toxic compounds such as hydrogen sulfide, or may transport sulfate as a sulfate ester into the sulfate-reducing bacteria.

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“…Samples were then assayed for the presence of thiol-containing compounds using UPLC–HR-ESI–MS as preciously described. 56…”

Section: Methodsmentioning

confidence: 99%

“…LC–MS spectral data for these compounds were recorded on an AB Sciex Quadrupole MS interfaced with an Agilent 1200 series LC as previously reported. 56…”

Section: Methodsmentioning

confidence: 99%

Identification of a Redox Active Thioquinoxalinol Sulfate Compound Produced by an Anaerobic Methane-Oxidizing Microbial Consortium

2019

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“…1-MES was prepared from 1-chloroethane-1-sulfonyl chloride following previously described methods . The compound was converted to the B derivative and purified by preparative TLC as previously described …”

Section: Methodsmentioning

confidence: 99%

“…These analyses were accomplished by derivatization of the thiols with monobromobimane (mBBr), purification of the resulting derivative by preparative thin layer chromatography (TLC), followed by ultraperformance liquid chromatography–high-resolution electrospray mass spectrometry (UPLC–HR-ESI-MS) to identify the thiol-containing products. The procedure used was basically those described for the recent identification of 3-mercaptopropionic acid (MPA) in growth media of methanogens . The results of these experiments failed to show the presence of any labeled HSCoM in the cells but did demonstrate the presence of HSCoM in the growth media.…”

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confidence: 99%

Identification and Biosynthesis of 1-Mercaptoethanesulfonic Acid (1-MES), an Analogue of Coenzyme M, Found Widely in the Methanogenic Archaea

White

2017

Biochemistry

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Here I report on the identification of 1-mercaptoethanesulfonic acid (1-MES), an analogue of 2-mercaptoethanesulfonic acid (coenzyme M, HSCoM). 1-MES and HSCoM were both present in the growth media of eight different methanogens at concentrations ranging from ∼1 to 100 μM. In an effort to determine a chemical origin of 1-MES, several plausible chemical routes were examined each assuming that HSCoM was the precursor. In all examined routes, no 1-MES was formed. However, 1-MES was formed when a solution of vinylsulfonic acid and sulfide were exposed to ultraviolet light. On the basis of these results, I conclude 1-MES is formed enzymatically. This was confirmed by growing a culture of Methanococcus maripaludis S2 in the presence of [1,1',2,2'-H]HSCoM and measuring the incorporation of deuterium into 1-MES. 1-MES incorporated three of the four deuteriums from the fed HSCoM. This result is consistent with the abstraction of a C-2 deuterium of the HSCoM, likely by a 5'-dAdoCH radical, followed by a radical rearrangement in which the sulfonic acid moves to position C-1, followed by abstraction of a H likely from 5'-dAdoCHD. At present, the reason for the production of 1-MES is not clear. This is the first report of the occurrence of 1-MES in Nature.

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“…Although both enzymes possessed malate dehydrogenase activity (converting oxaloacetate to ( S )-malate) [ 13 ], MJ1425 was identified as likely to be the biologically relevant ComC due to its kinetic parameters (higher V max and V max / K M for oxidation of ( R )-sulfolactate by NAD + to sulfopyruvate) and was classified as a sulfolactate dehydrogenase (EC 1.1.1.337) [ 10 , 11 ]. More recently, the M. jannaschii ComC (MJ1425) has been shown to also catalyze the NAD-dependent oxidation of 2-hydroxy-4-mercaptobutyric acid to 4-mercapto-2-oxobutyric acid, a precursor of the natural product 3-mercaptopropionic acid [ 14 ]. 3-mercaptopropionic acid is proposed to act as an alternative coenzyme M. Using a structure-based amino acid alignment, Irimia et al [ 10 ] identified three archaeal homologs to the M. jannaschii ComC (MJ1425) that should act as true sulfolactate dehydrogenases.…”

Section: Introductionmentioning

confidence: 99%

Expression, Purification, and Characterization of (R)-Sulfolactate Dehydrogenase (ComC) from the Rumen MethanogenMethanobrevibacter milleraeSM9

Schofield

Sang

Dey

et al. 2017

Archaea

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(R)-Sulfolactate dehydrogenase (EC 1.1.1.337), termed ComC, is a member of an NADH/NADPH-dependent oxidoreductase family of enzymes that catalyze the interconversion of 2-hydroxyacids into their corresponding 2-oxoacids. The ComC reaction is reversible and in the biosynthetic direction causes the conversion of (R)-sulfolactate to sulfopyruvate in the production of coenzyme M (2-mercaptoethanesulfonic acid). Coenzyme M is an essential cofactor required for the production of methane by the methyl-coenzyme M reductase complex. ComC catalyzes the third step in the first established biosynthetic pathway of coenzyme M and is also involved in methanopterin biosynthesis. In this study, ComC from Methanobrevibacter millerae SM9 was cloned and expressed in Escherichia coli and biochemically characterized. Sulfopyruvate was the preferred substrate using the reduction reaction, with 31% activity seen for oxaloacetate and 0.2% seen for α-ketoglutarate. Optimal activity was observed at pH 6.5. The apparent KM for coenzyme (NADH) was 55.1 μM, and for sulfopyruvate, it was 196 μM (for sulfopyruvate the Vmax was 93.9 μmol min−1 mg−1 and kcat was 62.8 s−1). The critical role of ComC in two separate cofactor pathways makes this enzyme a potential means of developing methanogen-specific inhibitors for controlling ruminant methane emissions which are increasingly being recognized as contributing to climate change.

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Occurrence and biosynthesis of 3-mercaptopropionic acid inMethanocaldococcus jannaschii

Cited by 12 publications

References 35 publications

Identification of a Redox Active Thioquinoxalinol Sulfate Compound Produced by an Anaerobic Methane-Oxidizing Microbial Consortium

Identification of a Redox Active Thioquinoxalinol Sulfate Compound Produced by an Anaerobic Methane-Oxidizing Microbial Consortium

Identification and Biosynthesis of 1-Mercaptoethanesulfonic Acid (1-MES), an Analogue of Coenzyme M, Found Widely in the Methanogenic Archaea

Expression, Purification, and Characterization of (R)-Sulfolactate Dehydrogenase (ComC) from the Rumen MethanogenMethanobrevibacter milleraeSM9

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