Around 100 proteins are produced inside the chloroplast but the vast majority must be imported. These proteins are synthesized in the cytosol as preproteins with cleavable targeting sequences. Several plastid types ot...Around 100 proteins are produced inside the chloroplast but the vast majority must be imported. These proteins are synthesized in the cytosol as preproteins with cleavable targeting sequences. Several plastid types other than chloroplasts exist. During plant development, one plastid type may be converted to another, a process referred to as plastid transition (Jarvis and Lopez-Juez, 2013). During plastid transitions, proteome remodeling occurs, and one set of imported proteins is replaced by another that is functionally adapted (Kleffmann et al., 2007). Moreover, plastid proteomes are known to be regulated in an environmentdependent fashion, and chloroplasts may respond to changing light conditions by regulating the composition and abundance of photosynthetic complexes.展开更多
The chloroplast is surrounded by a double-membrane envelope at which proteins, ions, and numerous metabolites including nucleotides, amino acids, fatty acids, and carbohydrates are exchanged between the two aqueous ph...The chloroplast is surrounded by a double-membrane envelope at which proteins, ions, and numerous metabolites including nucleotides, amino acids, fatty acids, and carbohydrates are exchanged between the two aqueous phases, the cytoplasm and the chloroplast stroma. The chloroplast envelope is also the location where the biosynthesis and accumulation of various lipids take place. By contrast to the inner membrane, which contains a number of specific transporters and acts as the permeability barrier, the chloroplast outer membrane has often been considered a passive compartment derived from the phagosomal membrane. However, the presence of galactoglycerolipids and β-barrel membrane proteins support the common origin of the outer membranes of the chloroplast envelope and extant cyanobacteria. Furthermore, recent progress in the field underlines that the chloroplast outer envelope plays important roles not only for translocation of various molecules, but also for regulation of metabolic activities and signaling processes. The chloroplast outer envelope membrane offers various interesting and challenging questions that are relevant to the understanding of organelle biogenesis, plant growth and development, and also membrane biology in general.展开更多
叶绿体作为植物及藻类细胞中含有内外双层被膜的细胞器,能够通过光合作用过程将光能转化为化学能。大部分的叶绿体蛋白由细胞核基因编码,其前体蛋白是在细胞质中的80S核糖体上合成的。前体蛋白在转运肽的引导下,通过跨越叶绿体外被膜和...叶绿体作为植物及藻类细胞中含有内外双层被膜的细胞器,能够通过光合作用过程将光能转化为化学能。大部分的叶绿体蛋白由细胞核基因编码,其前体蛋白是在细胞质中的80S核糖体上合成的。前体蛋白在转运肽的引导下,通过跨越叶绿体外被膜和内被膜的路径被传送进入叶绿体内部,进而到达发挥其生物学功能的目的微区。目前已知的前体蛋白转运的一个主要途径是通过叶绿体外被膜转运子(translocon in the outer envelope membrane of chloroplast, TOC)和内被膜转运子(translocon in the inner envelope membrane of chloroplast, TIC),在二者的协同作用下前体蛋白得以跨越双层被膜进入叶绿体。文章回顾了TOC-TIC超复合物的结构生物学研究进展,并深入探讨了各组件的功能特性以及前体蛋白易位至叶绿体内部的潜在途径和调控机制。展开更多
叶绿体外膜转运蛋白(translocon of the outer membrane of chloroplasts,TOC)介导了数千种位于细胞质中由细胞核编码的前体蛋白的识别与初始转运,对叶绿体生物合成及正常行使生物学功能具有重要作用。为明确番茄TOC复合体组分及其表达...叶绿体外膜转运蛋白(translocon of the outer membrane of chloroplasts,TOC)介导了数千种位于细胞质中由细胞核编码的前体蛋白的识别与初始转运,对叶绿体生物合成及正常行使生物学功能具有重要作用。为明确番茄TOC复合体组分及其表达特性,本研究基于番茄(Solanum lycopersicum)全基因组数据对番茄TOC复合体进行组分鉴定,并对其染色体定位、基因结构、保守基序、系统进化及弱光胁迫下表达模式等进行了分析。结果表明,番茄基因组中鉴定到10个TOC组分,分布于8条染色体上,分为4个基因家族,同一家族中的成员具有相似的基因结构和基序。e Plant提供的组织表达数据显示,TOC复合体不同组分在番茄中的表达具有组织特异性。qRT-PCR分析发现,番茄果实成熟过程中TOC复合体组分基因表达水平高于叶片组织,在这一过程中SlToc34-1、SlToc159-1和SlToc75表达上调,SlToc34-2、SlToc159-2和SlToc120表达下调;弱光胁迫处理下SlToc159-2、SlToc34-1和SlToc120表达水平均受到抑制,SlToc159-1和SlToc34-2没有明显的变化。研究成功克隆了SlToc159-2、SlToc34-1和SlToc34-2基因的cDNA序列,它们的氨基酸推导序列与拟南芥TOC组分蛋白具有很高的同源性,表明番茄是一种新的研究TOC复合体的有效模式植物。本研究为进一步探究番茄TOC复合体组分的功能提供参考。展开更多
基金the Swiss National Science Foundation (31003A_156998 and 31003A_176191).
文摘Around 100 proteins are produced inside the chloroplast but the vast majority must be imported. These proteins are synthesized in the cytosol as preproteins with cleavable targeting sequences. Several plastid types other than chloroplasts exist. During plant development, one plastid type may be converted to another, a process referred to as plastid transition (Jarvis and Lopez-Juez, 2013). During plastid transitions, proteome remodeling occurs, and one set of imported proteins is replaced by another that is functionally adapted (Kleffmann et al., 2007). Moreover, plastid proteomes are known to be regulated in an environmentdependent fashion, and chloroplasts may respond to changing light conditions by regulating the composition and abundance of photosynthetic complexes.
文摘The chloroplast is surrounded by a double-membrane envelope at which proteins, ions, and numerous metabolites including nucleotides, amino acids, fatty acids, and carbohydrates are exchanged between the two aqueous phases, the cytoplasm and the chloroplast stroma. The chloroplast envelope is also the location where the biosynthesis and accumulation of various lipids take place. By contrast to the inner membrane, which contains a number of specific transporters and acts as the permeability barrier, the chloroplast outer membrane has often been considered a passive compartment derived from the phagosomal membrane. However, the presence of galactoglycerolipids and β-barrel membrane proteins support the common origin of the outer membranes of the chloroplast envelope and extant cyanobacteria. Furthermore, recent progress in the field underlines that the chloroplast outer envelope plays important roles not only for translocation of various molecules, but also for regulation of metabolic activities and signaling processes. The chloroplast outer envelope membrane offers various interesting and challenging questions that are relevant to the understanding of organelle biogenesis, plant growth and development, and also membrane biology in general.
文摘叶绿体作为植物及藻类细胞中含有内外双层被膜的细胞器,能够通过光合作用过程将光能转化为化学能。大部分的叶绿体蛋白由细胞核基因编码,其前体蛋白是在细胞质中的80S核糖体上合成的。前体蛋白在转运肽的引导下,通过跨越叶绿体外被膜和内被膜的路径被传送进入叶绿体内部,进而到达发挥其生物学功能的目的微区。目前已知的前体蛋白转运的一个主要途径是通过叶绿体外被膜转运子(translocon in the outer envelope membrane of chloroplast, TOC)和内被膜转运子(translocon in the inner envelope membrane of chloroplast, TIC),在二者的协同作用下前体蛋白得以跨越双层被膜进入叶绿体。文章回顾了TOC-TIC超复合物的结构生物学研究进展,并深入探讨了各组件的功能特性以及前体蛋白易位至叶绿体内部的潜在途径和调控机制。
文摘叶绿体外膜转运蛋白(translocon of the outer membrane of chloroplasts,TOC)介导了数千种位于细胞质中由细胞核编码的前体蛋白的识别与初始转运,对叶绿体生物合成及正常行使生物学功能具有重要作用。为明确番茄TOC复合体组分及其表达特性,本研究基于番茄(Solanum lycopersicum)全基因组数据对番茄TOC复合体进行组分鉴定,并对其染色体定位、基因结构、保守基序、系统进化及弱光胁迫下表达模式等进行了分析。结果表明,番茄基因组中鉴定到10个TOC组分,分布于8条染色体上,分为4个基因家族,同一家族中的成员具有相似的基因结构和基序。e Plant提供的组织表达数据显示,TOC复合体不同组分在番茄中的表达具有组织特异性。qRT-PCR分析发现,番茄果实成熟过程中TOC复合体组分基因表达水平高于叶片组织,在这一过程中SlToc34-1、SlToc159-1和SlToc75表达上调,SlToc34-2、SlToc159-2和SlToc120表达下调;弱光胁迫处理下SlToc159-2、SlToc34-1和SlToc120表达水平均受到抑制,SlToc159-1和SlToc34-2没有明显的变化。研究成功克隆了SlToc159-2、SlToc34-1和SlToc34-2基因的cDNA序列,它们的氨基酸推导序列与拟南芥TOC组分蛋白具有很高的同源性,表明番茄是一种新的研究TOC复合体的有效模式植物。本研究为进一步探究番茄TOC复合体组分的功能提供参考。
