Novel pathway for assimilation of dimethylsulphoniopropionate widespread in marine bacteria
| Autor: | Mary Ann Moran, William B. Whitman, Vanessa A. Varaljay, I. Jonathan Amster, Christopher R. Reisch, Melissa J. Stoudemayer |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Pelagibacter ubique
Aquatic Organisms Multidisciplinary biology Bacteria Coenzyme A Microorganism Ruegeria fungi Microbial metabolism Sulfonium Compounds Methanethiol biology.organism_classification Roseobacter Metabolic pathway chemistry.chemical_compound Marine bacteriophage Biochemistry chemistry Bacterial Proteins Metagenomics Sulfhydryl Compounds Phylogeny |
| Zdroj: | Nature. 473(7346) |
| ISSN: | 1476-4687 |
| Popis: | Marine microbes can utilize dimethylsulphoniopropionate as a source of carbon and sulphur, and the metabolic end products are either dimethylsulphide (DMS) or methanethiol. Despite the importance of these pathways in marine ecosystems, and the interest in DMS as a potential 'anti-greenhouse' gas, the enzymes involved in the pathway to methanethiol have remained unidentified. The missing components of the pathway have now been identified as three novel enzymatic reactions and two novel coenzyme A-containing intermediates. The genes encoding these enzymes have also been identified, and are shown to be present in many bacterioplankton, suggesting that the pathway is widespread in the ocean. Dimethylsulphoniopropionate (DMSP) accounts for up to 10% of carbon fixed by marine phytoplankton in ocean surface waters1,2, producing an estimated 11.7–103 Tmol S per year3, most of which is processed by marine bacteria through the demethylation/demethiolation pathway4. This pathway releases methanethiol (MeSH) instead of the climatically active gas dimethylsulphide (DMS) and enables marine microorganisms to assimilate the reduced sulphur5,6,7. Despite recognition of this critical microbial transformation for over two decades, the biochemical pathway and enzymes responsible have remained unidentified. Here we show that three new enzymes related to fatty acid β-oxidation constitute the pathway that assimilates methylmercaptopropionate (MMPA), the first product of DMSP demethylation/demethiolation, and that two previously unknown coenzyme A (CoA) derivatives, 3-methylmercaptopropionyl-CoA (MMPA-CoA) and methylthioacryloyl-CoA (MTA-CoA), are formed as novel intermediates. A member of the marine roseobacters, Ruegeria pomeroyi DSS-3, requires the MMPA-CoA pathway for MMPA assimilation and MeSH production. This pathway and the ability to produce MeSH from MMPA are present in diverse bacteria, and the ubiquitous SAR11 clade bacterium Pelagibacter ubique possesses enzymes for at least the first two steps. Analysis of marine metagenomic data indicates that the pathway is widespread among bacterioplankton in the ocean surface waters, making it one of the most important known routes for acquisition of reduced carbon and sulphur by surface ocean heterotrophs. |
| Databáze: | OpenAIRE |
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