Dimethylsulfoniopropionate (DMSP) is widespread in the oceans, and its biological metabolite, dimethyl sulfide (DMS), plays an important role in the atmosphere. The Antarctic region has become a hotspot in DMS studies due to the high spatial and temporal variability in DMS(P) concentration, but the level of bacterial DMS production remains unclear. In this study, a bacterium isolated from Antarctic floating ice, Rhodococcus sp. NJ‐530, was found to metabolize DMSP into DMS, and the rate of DMS production was measured as 3.96 pmol·mg protein−1·h−1. Rhodococcus sp. NJ‐530 had a DddD‐Rh enzyme containing two CaiB domains, which belonged to the CoA‐transferase III superfamily. However, the DddD‐Rh had a molecular weight of 73.21 kDa, which was very different from previously characterized DddD enzymes in sequence and evolution. In vitro assays showed that DddD‐Rh was functional in the presence of acetyl‐CoA. This was the first functional DddD from Gram‐positive Actinobacteria. Moreover, a quantitative real‐time polymerase chain reaction revealed that high temperature facilitated the expression of dddD‐Rh, and changes of salinity had little effect on it. This study adds new evidence to the bacterial DMS production in the Southern Ocean and provides a basis for investigating the metabolic mechanism of DMSP in extreme environments.

中文翻译：

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在南极红球菌中鉴定用于二甲基硫醚生产的功能性 dddD -Rh。NJ-530

二甲基磺基丙酸酯（DMSP）广泛存在于海洋中，其生物代谢物二甲硫醚（DMS）在大气中起着重要作用。由于 DMS(P) 浓度的高时空变异性，南极地区已成为 DMS 研究的热点，但细菌 DMS 产生的水平仍不清楚。在这项研究中，从南极浮冰中分离出一种细菌，红球菌属。发现 NJ-530 将 DMSP 代谢为 DMS，测得 DMS 生成速率为 3.96 pmol·mg 蛋白质-1·h-1。红球菌属 NJ-530 有一个 DddD-Rh 酶，它包含两个 CaiB 结构域，属于 CoA 转移酶 III 超家族。然而，DddD-Rh 的分子量为 73.21 kDa，这在序列和进化上与先前表征的 DddD 酶有很大不同。体外试验表明，DddD-Rh 在乙酰辅酶 A 存在下起作用。这是来自革兰氏阳性放线菌的第一个功能性 DddD。此外，实时定量聚合酶链反应表明，高温促进了 dddD-Rh 的表达，而盐度的变化对其影响不大。该研究为南大洋细菌DMS的产生增加了新的证据，并为研究DMSP在极端环境中的代谢机制提供了基础。