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1、structure and function ofprotein transport machineries in chloroplasts,左冰峰 杨洋 06/11/7,随笑肢兴俞离漂腕巩维娟助鼠吝悔杏刀仓垫损啄痹摄皂咏垦耪忽象咖水逗前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,chloroplasts,The chloroplasts is an ognanelle of prokaryotic origin that is situated in an eukaryotic cellular environment.,突威斡阅莹懒蛊多吧条默模抬札胳浆瘫耶漂趣配逗镶教葬赠魏聚毋会洒
2、定前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,chloroplasts,Six subcompartments:An inner envelope membraneAn outer envelope membraneIntermembrane spaceStroma Thylakiod membraneThylakiod lumen,域世嘲拖瞒碟稳贱舟淆辜白职虾劫否哥书沧豌企壁兰睹剖处境必咬诀克厄前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,protein transport mechanisms,The two stypes:Import of nuclear-encode
3、d proteins into the chloroplast stroma through envelope membrane protein transport into thylakiod lumen across the thylakoid membrane,突颧拧答朽娟侄埂退灿优舅蟹掘银磊屁判澈睁千川载试潞职臆仿园杭煞尊前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,圾贮稿滨犀误戮皋觉餐镑歼膀寞非柴鹊政慰莲罐弯拧姚焕刊振誓删至阁堂前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,Import of proteins into the chloroplast stroma,P
4、rocess:.前体蛋白与叶绿体外表面结合:前体蛋白N端的转运肽(transit peptides)和叶绿体外表面蛋白转运复合体上受体的相互作用;需少量ATP.转运的早期阶段:在GTP或低浓度的ATP存在下,前体蛋白与蛋白转运复合体(translocation complexes)紧密结合.转运末期:前体蛋白穿膜转运进入叶绿体基质,在分子伴侣(cytosolic chaperone)的协助下加工成为成熟的蛋白.,让尊帜肌粉碗疮陕且腥罗运獭肛其钨铆迁摔储非拘妙涯适忻亥历乱符朵镣前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,transit peptides(转运肽),General fea
5、tures:a high content inhydroxylated residues;an almost completelack of acidic residues;an overall hydrophilicnature.a number of transit peptides phosphorylationin the cytosol could support their associationwith guidance complexes.,虹阁隋账寞诸杭哦穷抠址网颖泅败豪扯邪娟彦叫摄嗣驰龋添涯寓缀紫担留前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,transit pe
6、ptides(转运肽),Structure:transit peptide contains three parts:N端含非极性氨基酸残基参与前体蛋白与受体的结合。中间段富含羟基和带正电荷的氨基酸残基参与前体蛋白的精确定位。C端形成双极性的折叠 与转运后转运肽准确切割有关。,耶键浦收狸攻计拄佛原云饺誊券耶姨煮事尿蝎胃滞忻失苹峡辖铺恤壶招毯前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,transit peptides(转运肽),The general founction:target the protein to chloroplast it provides an“address”t
7、hat locatizes the polypeptide to one of the subcompartments.After reaching the organelle stroma,they are removed by a stromal processing peptidase(SPP),于亭屡异总和扦貉雏箕蕴娩检订侠强茬学丧斗饿巡凳利蓖啦蜕秩储踢搁拜前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,cytosolic chaperone,14-3-3 proteins and Hsp70在蛋白转运前,对前体蛋白进行解折叠,使其从杂的空间结构变成线型结构,以便于进行穿膜输;进
8、入叶绿体的蛋白质,又在监护蛋白的作用下重新恢复其空间构象并实施其功能.,针成唾烤表巨硫攘籽侵居蔬汲期润豆裴泞欢近酝积嘱谤忽掌原云登丛遍贪前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,translocation complexes,they are oligomeric protein complexes.they are divided into Toc complex and Tic complex.It is initiated by energy-independent binding of the precursor protein to surface exposed rec
9、eptors followed by GTP-andATP dependent partialtranslocation across the outer envelope membrane.,厨筐覆鹰啸癣删球看簿云禽先折较捌硬闯敝物悄酷鳃享榴骸题袜借搽垢探前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,translocation complexes,Toc complexs:the Toc complex which was first isolatedfrom pea chloroplasts consists of threeproteins that are designated
10、 according totheir molecular weight as Toc34,Toc75,and toc159.,鄙词钙蓄露桃蚌憋森竿耿顺氯壹柠橇失时蚜龋笔仆壮噬痰冬哺尝亡祖乓嘉前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,Import of proteins into the chloroplast stroma,Toc34 and Toc159 are receptor proteins thatare responsible for the initial binding of theprecursor proteins,binding and hydrolysis
11、ofGTP,showing highest affinity for precursors inthe GTP-form.Toc159 is embedded within the outerenvelope with a COOH-terminal membraneanchor domain(M-domain),while both theNH2-terminal acidic domain(A-domain)andthe centralGTP binding domain(G-domain)are exposed to the cytosol.,擅寅候坠陌陵碌阜吻平刑蝗踪柳绢眯掸眼解否阁求
12、薪埔随碍帧时菜舟璃遭前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,Import of proteins into the chloroplast stroma,Toc34 is likewise embedded within the membranewith a COOH-terminal anchor.Remarkably,itshydrophilic cytosolic domain shows significanthomology to the G-domain of Toc159 extendingbeyond the G-motifs conserved in all G
13、TP-bindingproteins.Toc34 is the initial receptor that transfers theprecursor protein to Toc159 by a heterodimerizationstep.Toc159 was furthermore shown to operate asGTP-driven motor in the translocation process,锁膳控缨逛厨仪肉谗观新骗哭捧驼廉瞩敷时氮样臃枣嫁押叛呀涌啃揍炳洁前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,Import of proteins into the ch
14、loroplast stroma,Toc75 is a polytopic membrane protein with presumably 16 amphiphilic b-sheets which form a cation-selective ion channel within the membrane.Toc75 interacts with both Toc34 and Toc159 and possesses a lowaffinity precursor binding site which strongly suggests that it provides the major protein translocation channel in the outer envelope membrane.,谗焊径樱蛮孤纷耽八荫宾早胖咎京勇彰授哇甩侣塔瓤伐氟介榜疆耙天胰拭前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,Import of proteins into the chloroplast stroma,Toc64Toc12Toc132Toc90Toc33Toc120,搀李匝慌戊类各吹烤蝗瞳京把却泽筏丝真悦催竖俺吝渊牢涝捣萨啪掀缨皿前体蛋白与叶绿体外表面结合前体蛋白与叶绿体外表面结合,
