Identification of dimethylamine monooxygenase in marine bacteria reveals a metabolic bottleneck in the methylated amine degradation pathway.
Identification of dimethylamine monooxygenase in marine bacteria reveals a metabolic bottleneck in the methylated amine degradation pathway.
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DOI：
10.1038/ismej.2017.31
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发表时间：
2017-07
期刊：
影响因子：
--
通讯作者：
Chen Y
中科院分区：
文献类型：
--
作者：
Lidbury I;Mausz MA;Scanlan DJ;Chen Y
甲基化胺（MAs）在海洋环境中普遍存在，它们随后进入大气可导致气溶胶的形成，最终形成云凝结核。因此，这些化合物在气候调节中具有潜在的重要作用。我们以波梅罗依鲁氏为模型，鉴定了编码二甲胺（DMA）单加氧酶（dmmABC）的基因，并证明该酶可将DMA降解为一甲基胺（MMA）。虽然重组大肠杆菌的酶活性只需要dmmABC，但我们发现，R. pomeroyi在MAs上生长还需要一个额外的基因dmmD。dmmDABC基因在多种海洋细菌的基因组中缺失，包括世界性的SAR11分支的所有代表。因此，海洋宏基因组中dmmDABC的丰度大大低于MA降解途径中其他代谢步骤所需的基因。因此，在海洋MA降解途径中存在遗传和潜在的代谢瓶颈。我们的数据解释了dma衍生的二次有机气溶胶（SOAs）是在北大西洋和热带大西洋的细海洋颗粒中检测到的最丰富的SOAs。
Methylated amines (MAs) are ubiquitous in the marine environment and their subsequent flux into the atmosphere can result in the formation of aerosols and ultimately cloud condensation nuclei. Therefore, these compounds have a potentially important role in climate regulation. Using Ruegeria pomeroyi as a model, we identified the genes encoding dimethylamine (DMA) monooxygenase (dmmABC) and demonstrate that this enzyme degrades DMA to monomethylamine (MMA). Although only dmmABC are required for enzyme activity in recombinant Escherichia coli, we found that an additional gene, dmmD, was required for the growth of R. pomeroyi on MAs. The dmmDABC genes are absent from the genomes of multiple marine bacteria, including all representatives of the cosmopolitan SAR11 clade. Consequently, the abundance of dmmDABC in marine metagenomes was substantially lower than the genes required for other metabolic steps of the MA degradation pathway. Thus, there is a genetic and potential metabolic bottleneck in the marine MA degradation pathway. Our data provide an explanation for the observation that DMA-derived secondary organic aerosols (SOAs) are among the most abundant SOAs detected in fine marine particles over the North and Tropical Atlantic Ocean.
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