Mechanistic insights into the key marine dimethylsulfoniopropionate synthesis enzyme DsyB/DSYB  

作　　者：Chun-Yang Li Jason C.Crack Simone Newton-Payne Andrew R.J.Murphy Xiu-Lan Chen Benjamin J.Pinchbeck Shun Zhou Beth T.Williams Ming Peng Xiao-Hua Zhang Yin Chen Nick E.Le Brun Jonathan D.Todd Yu-Zhong Zhang 

机构地区：[1]Frontiers Science Center for Deep Ocean Multispheres and Earth System,College of Marine Life Sciences,Ocean University of China,Qingdao,China [2]State Key Laboratory of Microbial Technology,Marine Biotechnology Research Center,Shandong University,Qingdao,China [3]Laboratory for Marine Biology and Biotechnology,Pilot National Laboratory for Marine Science and Technology,Qingdao,Shandong,China [4]School of Chemistry,Centre for Molecular and Structural Biochemistry,University of East Anglia,Norwich Research Park,Norwich,UK [5]School of Biological Sciences,University of East Anglia,Norwich,UK [6]School of Life Sciences,University of Warwick,Coventry,UK

出　　处：《mLife》2022年第2期114-130,共17页微生物（英文）

基　　金：the National Science Foundation of China(Grant Nos.91851205,42076229,31961133016);the National Key Research and Development Program of China(Grant No.2021YFA0909600);the Fundamental Research Funds for the Central Universities(Grant Nos.202172002,202041011);the Major Scientific and Technological Innovation Project of Shandong Province(Grant No.2019JZZY010817);the Program of Shandong for Taishan Scholars(Grant No.tspd20181203);the grant of Laboratory for Marine Biology and Biotechnology(OF2019NO02);Pilot National Laboratory for Marine Science and Technology(Qingdao);the United Kingdom's Natural and Environmental Research Council(NERC,NE/P012671/1,and NE/N002385/1);the United Kingdom's Biotechnology and Biological Sciences Research Council(BBSRC,BB/P006140/1).

摘　　要：Marine algae and bacteria produce approximately eight billion tonnes of the organosulfur molecule dimethylsulfoniopropionate(DMSP)in Earth's surface oceans annually.DMSP is an antistress compound and,once released into the environment,a major nutrient,signaling molecule,and source of climate-active gases.The methionine transamination pathway for DMSP synthesis is used by most known DMSP-producing algae and bacteria.The S-directed S-adenosylmethionine(SAM)-dependent 4-methylthio-2-hydroxybutyrate(MTHB)S-methyltransferase,encoded by the dsyB/DSYB gene,is the key enzyme of this pathway,generating S-adenosylhomocysteine(SAH)and 4-dimethylsulfonio-2-hydroxybutyrate(DMSHB).DsyB/DSYB,present in most haptophyte and dinoflagellate algae with the highest known intracellular DMSP concentrations,is shown to be far more abundant and transcribed in marine environments than any other known S-methyltransferase gene in DMSP synthesis pathways.Furthermore,we demonstrate in vitro activity of the bacterial DsyB enzyme from Nisaea denitrificans and provide its crystal structure in complex with SAM and SAH-MTHB,which together provide the first important mechanistic insights into a DMSP synthesis enzyme.Structural and mutational analyses imply that DsyB adopts a proximity and desolvation mechanism for the methyl transfer reaction.Sequence analysis suggests that this mechanism may be common to all bacterial DsyB enzymes and also,importantly,eukaryotic DSYB enzymes from e.g.,algae that are the major DMSP producers in Earth's surface oceans.

关 键 词：catalytic mechanism DMSP synthesis marine sulfur cycle S-methyltransferase 

分 类 号：Q936[生物学—微生物学]