Frontiers Science Center for Deep Ocean Multispheres and Earth System, College of Marine Life Sciences, and Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, China.
Laboratory for Marine Ecology and Environmental Science, Qingdao Marine Science and Technology Center, Qingdao, China.
Nat Microbiol. 2024 Oct;9(10):2614-2625. doi: 10.1038/s41564-024-01788-6. Epub 2024 Aug 28.
Hydrogen sulfide (HS), methanethiol (MeSH) and dimethylsulfide (DMS) are abundant sulfur gases with roles in biogeochemical cycling, chemotaxis and/or climate regulation. Catabolism of the marine osmolyte dimethylsulfoniopropionate (DMSP) is a major source of DMS and MeSH, but both also result from S-methylation of HS via MddA, an HS and MeSH S-methyltransferase whose gene is abundant in soil but scarce in marine environments. Here we identify the S-adenosine methionine (SAM)-dependent MeSH and HS S-methyltransferase 'MddH', which is widespread in diverse marine bacteria and some freshwater and soil bacteria. mddH is predicted in up to ~5% and ~15% of seawater and coastal sediment bacteria, respectively, which is considerably higher than mddA. Furthermore, marine mddH transcript levels are similar to those for the most abundant DMSP lyase gene dddP. This study implies that the importance of HS and MeSH S-methylation pathways in marine environments is significantly underestimated.
硫化氢 (HS)、甲硫醇 (MeSH) 和二甲硫 (DMS) 是丰富的含硫气体，在生物地球化学循环、化学趋性和/或气候调节中发挥作用。海洋渗透剂二甲硫基丙酸盐 (DMSP) 的分解代谢是 DMS 和 MeSH 的主要来源，但 DMS 和 MeSH 也源自通过 MddA 将 HS 进行 S-甲基化，MddA 是一种 HS 和 MeSH 的 S-甲基转移酶，其基因在土壤中丰富，但在海洋环境中稀缺。在这里，我们确定了依赖 S-腺苷甲硫氨酸 (SAM) 的 MeSH 和 HS S-甲基转移酶 'MddH'，它广泛存在于各种海洋细菌以及一些淡水和土壤细菌中。mddH 分别被预测存在于高达约 5%和 15%的海水中和沿海沉积物细菌中，这明显高于 mddA。此外，海洋 mddH 转录本水平与最丰富的 DMSP 裂解酶基因 dddP 的转录本水平相似。本研究表明，HS 和 MeSH S-甲基化途径在海洋环境中的重要性被严重低估。
