Frontiers Science Center for Deep Ocean Multispheres and Earth System & College of Marine Life Sciences, Ocean University of China, Qingdao, China.
State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Qingdao, China.
Environ Microbiol. 2023 Jul;25(7):1238-1249. doi: 10.1111/1462-2920.16355. Epub 2023 Feb 28.
Dimethylsulfoniopropionate (DMSP) is a marine organosulfur compound with important roles in stress protection, marine biogeochemical cycling, chemical signalling and atmospheric chemistry. Diverse marine microorganisms catabolize DMSP via DMSP lyases to generate the climate-cooling gas and info-chemical dimethyl sulphide. Abundant marine heterotrophs of the Roseobacter group (MRG) are well known for their ability to catabolize DMSP via diverse DMSP lyases. Here, a new DMSP lyase DddU within the MRG strain Amylibacter cionae H-12 and other related bacteria was identified. DddU is a cupin superfamily DMSP lyase like DddL, DddQ, DddW, DddK and DddY, but shares <15% amino acid sequence identity with these enzymes. Moreover, DddU proteins forms a distinct clade from these other cupin-containing DMSP lyases. Structural prediction and mutational analyses suggested that a conserved tyrosine residue is the key catalytic amino acid residue in DddU. Bioinformatic analysis indicated that the dddU gene, mainly from Alphaproteobacteria, is widely distributed in the Atlantic, Pacific, Indian and polar oceans. For reference, dddU is less abundant than dddP, dddQ and dddK, but much more frequent than dddW, dddY and dddL in marine environments. This study broadens our knowledge on the diversity of DMSP lyases, and enhances our understanding of marine DMSP biotransformation.
二甲亚砜（DMSP）是一种海洋有机硫化合物，在应激保护、海洋生物地球化学循环、化学信号传递和大气化学等方面具有重要作用。多种海洋微生物通过 DMSP 裂解酶将 DMSP 代谢为气候冷却气体和信息化学物质二甲硫醚。罗斯伯里氏菌组（MRG）中的丰富海洋异养菌以通过多种 DMSP 裂解酶代谢 DMSP 的能力而闻名。在此，鉴定了 MRG 菌株 Amylibacter cionae H-12 中的新型 DMSP 裂解酶 DddU 及其它相关细菌。DddU 是一种 cupin 超家族 DMSP 裂解酶，与 DddL、DddQ、DddW、DddK 和 DddY 相似，但与这些酶的氨基酸序列同一性<15%。此外，DddU 蛋白与其它 cupin 含 DMSP 裂解酶形成独特的分支。结构预测和突变分析表明，保守的酪氨酸残基是 DddU 中的关键催化氨基酸残基。生物信息学分析表明，dddU 基因主要来自α变形菌门，广泛分布于大西洋、太平洋、印度洋和极地海洋。作为参考，dddU 在海洋环境中的丰度低于 dddP、dddQ 和 dddK，但比 dddW、dddY 和 dddL 更为常见。本研究拓宽了我们对 DMSP 裂解酶多样性的认识，并增进了我们对海洋 DMSP 生物转化的理解。
