Laboratori de Microbiologia, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain.
School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
Nat Commun. 2015 Mar 25;6:6579. doi: 10.1038/ncomms7579.
The volatile compound dimethylsulphide (DMS) is important in climate regulation, the sulphur cycle and signalling to higher organisms. Microbial catabolism of the marine osmolyte dimethylsulphoniopropionate (DMSP) is thought to be the major biological process generating DMS. Here we report the discovery and characterization of the first gene for DMSP-independent DMS production in any bacterium. This gene, mddA, encodes a methyltransferase that methylates methanethiol and generates DMS. MddA functions in many taxonomically diverse bacteria including sediment-dwelling pseudomonads, nitrogen-fixing bradyrhizobia and cyanobacteria, and mycobacteria including the pathogen Mycobacterium tuberculosis. The mddA gene is present in metagenomes from varied environments, being particularly abundant in soil environments, where it is predicted to occur in up to 76% of bacteria. This novel pathway may significantly contribute to global DMS emissions, especially in terrestrial environments and could represent a shift from the notion that DMSP is the only significant precursor of DMS.
挥发性化合物二甲基硫（DMS）在气候调节、硫循环和向高等生物发出信号方面很重要。微生物对海洋渗透剂二甲基硫代丙酸酯（DMSP）的分解代谢被认为是产生 DMS 的主要生物过程。在这里，我们报告了在任何细菌中发现并鉴定出的第一个与 DMSP 无关的 DMS 产生的基因。该基因 mddA 编码一种甲基转移酶，可将甲硫醇甲基化生成 DMS。MddA 在许多分类上不同的细菌中发挥作用，包括沉积物中栖息的假单胞菌、固氮慢生根瘤菌和蓝细菌，以及分枝杆菌，包括病原体结核分枝杆菌。mddA 基因存在于来自不同环境的宏基因组中，在土壤环境中尤其丰富，据预测，在高达 76%的细菌中存在该基因。这种新途径可能会显著促进全球 DMS 的排放，特别是在陆地环境中，这可能代表着从 DMSP 是 DMS 唯一重要前体的概念转变。
