《MRL7, a Thioredoxin-Like Fold Protein with Disulfide Reductase Activity, Regulates Chloroplast Gene Expression and Chloroplast Biogenesis in Arabidopsis thaliana》.pdf

M olecularPlant ·Volume7 ·Number1 ·Pages206-217 ·January2014 RESEARCHARTICLE AtECB1／MRL7，aThioredoxin—LikeFoldProtein withDisulfideReductaseActivity,Regulates ChloroplastGeneExpressionandChloroplast Qing-BoYu．QianMa。，Meng-MengKong，Tuan-TuanZhao。，Xiao-LeiZhang，QueZhou。， ChaoHuang，KangChong ‘andZhong-NanYang，’ aBiologyDepartment，LifeandEnvironmentalCollege，ShanghaiNormalUniversity,Shanghai200234，China bNationalLaboratoryofPlantMolecularGenetics，InstituteofPlantPhysologyandEcology,ShanghaiInstitutesforBiologicalSciencestheChinese AcademyofSciences．Shanghai200032，China cResearchCenterforMolecularandDevelopmentalBiology,KeyLaboratoryofPhotosynthesisandEnvironmentalMolecularPhysiology,Instituteof Botany,theChineseAcademyofSciences，100093Beijing，China ABSTRACT Plastid-encodedRNApolymerase(PEP)iscloselyassociatedwithnumerousfactorstoformPEPcomplexfor plastidgeneexpressionandchloroplastdevelopment．However,itisnotclearhow PEPcomplexareregulated inchloro- plast．Herelonethioredoxin．1ikefoldprotein．Arabidopstsearlychloroplastbiogenesis1(AtECB1、。analleleofMRL7|was identifiedtoregulatePEPfunctionandchloroplastbiogenesis．TheknockoutIinesforA CB1displayedalbinophenotype andimpairedchloroplastdevelopment．ThetranscriptsofPEP．dependentplastidgeneswerebarelydetected，suggesting thatthePEPactivity isalmostIostinatecb1．1．AlthoughAtECB1wasnotidentifiedinPEPcomplex，ayeasttwo．hybrid assayandpull—downexperimentsdemonstratedthatitcan interactwithTrxZandFSD3．two intrinsicsubunitsofPEP complex。respectively．ThisindicatesthatAtECB1mayplayaregulatoryroleforPEP—dependentplastidgeneexpression throughthesetwosubunits．AtECB1containsa6I【I3BBc【structureInthethioredoxin—likefolddomainandlacksthetypicaI C-X-X-Cactivesitemotif．1nsulinassaydemonstratedthatAtECB1harborsdisulfidereductaseactivity ／nvitrousingthe purifiedrecombinantAtECB1protein．Thisshowedthatthisthioredoxin-likefoldprotein．AtECB1alsohasthethioredoxin activity．AtECB1mayplayarol