Vitamin B_(12)-auxotrophy in dinoflagellates caused by incomplete or absent cobalamin-independent methionine synthase genes(metE)  

作　　者：Siheng Lin Zhangxi Hu Xiaoying Song Christopher JGobler Ying Zhong Tang 

机构地区：[1]CAS Key Laboratory of Marine Ecology and Environmental Sciences,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China [2]Laboratory for Marine Ecology and Environmental Science,Qingdao National Laboratory for Marine Science and Technology,Qingdao 266237,China [3]Center for Ocean Mega-Science,Chinese Academy of Sciences,Qingdao 266071,China [4]University of Chinese Academy of Sciences,Beijing 100049,China [5]School of Marine and Atmospheric Sciences,Stony Brook University,NY,11790,USA [6]Department of Biological Sciences and Biotechnology,Minnan Normal University,Zhangzhou 363000,China

出　　处：《Fundamental Research》2022年第5期727-737,共11页自然科学基础研究（英文版）

基　　金：edge the financial support from the National Natural Science Foundation of China(Grant No.41776125);the Key Deployment Project of Centre for Ocean Mega-Research of Science,Chinese Academy of Sciences(Grant No.COMS2019Q09);the Science&Technology Basic Resources Investigation Program of China(Grant No.2018FY100200);National Natural Science Foundation of China(Grants Nos.41976134 and 61533011);the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(Grant No.2018SDKJ0504-2);supported by the Chicago Community Trust.

摘　　要：Dinoflagellates are responsible for most marine harmful algal blooms (HABs) and play vital roles in many ocean processes.More than 90% of dinoflagellates are vitamin B_(12) auxotrophs and that B_(12) availability can control dinoflagellate HABs,yet the genetic basis of B_(12) auxotrophy in dinoflagellates in the framework of the ecology of dinoflagellates and particularly HABs,which was the objective of this work.Here,we investigated the presence,phylogeny,and transcription of two methionine synthase genes(B_(12)-dependent metH and B_(12)-independent metE)via searching and assembling transcripts and genes from transcriptomic and genomic databases,cloning 38 cDNA isoforms of the two genes from 14 strains of dinoflagellates,measuring the expression at different scenarios of B_(12),and comprehensive phylogenetic analyses of more than 100 organisms.We found that 1)metH was present in all 58 dinoflagellates accessible and metE was present in 40 of 58 species,2)all metE genes lacked N-terminal domains,3)metE of dinoflagellates were phylogenetically distinct from other known metE genes,and 4)expression of metH in dinoflagellates was responsive to exogenous B_(12) levels while expression of metE was not responding as that of genuine metE genes.We conclude that most,hypothetically all,dinoflagellates have either non-functional metE genes lacking N-terminal domain for most species,or do not possess metE for other species,which provides the genetic basis for the widespread nature of B_(12) auxotrophy in dinoflagellates.The work elucidated a fundamental aspect of the nutritional ecology of dinoflagellates.

关 键 词：Harmful algal blooms(HABs)Dinoflagellates Vitamin B_(12) (cobalamin) Auxotrophy Methionine synthase genes Phytoplankton ecology 

分 类 号：Q949.24[生物学—植物学]