A Thylakoid Membrane Protein Functions Synergistically with GUN5 in Chlorophyll Biosynthesis  

作　　者：Chi Zhang Bin Zhang Baicong Mu Xiaojiang Zheng Fugeng Zhao Wenzhi Lan Aigen Fu Sheng Luan 

机构地区：[1]The Key Laboratory of Western Resources Biology and Biological Technology,College of Life Sciences,Northwest University,Xi’an 710069,China [2]Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology,College of Life Sciences,Nanjing University,Nanjing 210093,China [3]Temasek Life Sciences Laboratory,Singapore 117604,Republic of Singapore [4]Department of Plant and Microbial Biology,University of California,Berkeley,CA 94720,USA

出　　处：《Plant Communications》2020年第5期100-110,共11页植物通讯（英文）

基　　金：supported by the National Natural Science Foundation of China(grant no.31900220 to C.Z.,and 31770267 to W.L.);the National Science Foundation(MCB-1714795 to S.L.).

摘　　要：Chlorophyll(Chl)is essential for photosynthetic reactions and chloroplast development.While the enzymatic pathway for Chl biosynthesis is well established,the regulatory mechanism underlying the homeostasis of Chl levels remains largely unknown.In this study,we identified CBD1(Chlorophyll Biosynthetic Defect1),which functions in the regulation of chlorophyll biosynthesis.The CBD1 gene was expressed specifically in green tissues and its protein product was embedded in the thylakoid membrane.Furthermore,CBD1 was precisely co-expressed and functionally correlated with GUN5(Genome Uncoupled 5).Analysis of chlorophyll metabolic intermediates indicated that cbd1 and cbd1gun5 mutants over-accumulatedmagnesium protoporphyrin Ⅸ(Mg-Proto Ⅸ).In addition,the cbd1 mutant thylakoid contained less Mg than the wild type not only as a result of lower Chl content,but also implicating CBD1 in Mg transport.This was supported by the finding that CBD1 complemented a Mg^(2+)uptake-deficient Salmonella strain under low Mg conditions.Taken together,these results indicate that CBD1 functions synergistically with CHLH/GUN5 in Mg-Proto IX processing,and may serve as a Mg-transport protein to maintain Mg homeostasis in the chloroplast.

关 键 词：chlorophyll biosynthesis MAGNESIUM thylakoid membrane GUN5 magnesium protoporphyrin 

分 类 号：Q94[生物学—植物学]