玫瑰杆菌(Roseobacter)参与海洋表层有机硫DMSP循环的机制及生理生态学适应的生物化学基础

二甲基巯基丙酸内盐（DMSP）是海洋有机硫循环的重要载体物质。玫瑰杆菌是表层海洋中代谢DMSP的重要类群，能裂解DMSP产生DMS和丙烯酸。DMS进入大气层参与云的形成，对全球气候变化有重要影响。本项目综合利用微生物生理学、遗传学、生物化学、结构生物学、酶学等技术，开展如下研究：（1）发现和鉴定海洋玫瑰杆菌转运DMSP的ABC型转运系统，并揭示识别和结合DMSP的分子机制；（2）揭示DMSP裂解酶DddD、DddY催化裂解DMSP的生化机制，有望发现新的DMSP裂解机制；（3）揭示玫瑰杆菌代谢丙烯酸和丙烯酰辅酶A，解除其毒性的生化机制；（4）从酶促反应动力学新视角，揭示玫瑰杆菌高效吸收并富集DMSP、低效率裂解DMSP、高效代谢丙烯酸及丙烯酰辅酶A并解除其毒性的分子机制。上述研究结果将为阐明海洋有机硫DMSP循环的生物地球化学和生理生态学机制提供重要依据，具有重要理论意义。

Dimethylsulfoniopropionate (DMSP) is an important participant in global sulfur cycle. Roseobacter is an important bacterial group that metabolizes DMSP by cleaving DMSP into DMS and acrylate. When released into the atmosphere from the oceans, DMS is oxidized, forming cloud condensation nuclei that may influence the global weather and climate. By using the techniques of microbiological physiology, genetics, biochemistry, structural biology and enzymology, this program will carry on the following studies: (1) identify the ABC transporter for DMSP in Roseobacter and insight into the DMSP recognition mechanism, (2) study the mechanism of DddD and DddY to cleave DMSP into into DMS and acrylate, which may reveal some novel catalytic mechanisms for DMSP cleavage, (3) study the mechanism of Roseobacter to metabolize acrylate and acrylic CoA and detoxify their toxicity. (4) elucidate the biochemical basis for high efficient absorption and enrichment of DMSP, low efficient cleavage of DMSP and high efficient detoxification of acrylate and acrylic CoA in Roseobacter based on enzymatic kinetics. The results of this program will provide important evidence for clarifying the biogeochemical mechanism and the physiological and ecological mechanism of DMSP cycling, which will have high theoretical significance.