Pentatricopepetide repeat （PPR） proteins are a large family of RNA-binding proteins involved in RNA meta- bolism in plant organelles. Although many PPR proteins have been functionally studied, few of them are identi...Pentatricopepetide repeat （PPR） proteins are a large family of RNA-binding proteins involved in RNA meta- bolism in plant organelles. Although many PPR proteins have been functionally studied, few of them are identified with a function in mitochondrial RNA stability. By using a reverse genetic approach, we characterized the role of the mitochondrion-targeted PPR78 protein in nad5 mature mRNA stability and maize （Zea mays） seed development. Loss of PPR78 function leads to a dramatic reduction in the steady-state level of mitochondrial nad5 mature mRNA, blocks the assembly of complex I in the electron transport chain, and causes an arrest in embryogenesis and endosperm development. Characterization of a second strong allele confirms the function of PPR78 in nad5 mRNA accumulation and maize seed development. The generation of mature nad5 requires the assembly of three distinct precursor RNAs via transsplicing reactions, and the accumulation ofnad5T1 precursor is reduced in the ppr78 mutants. However, it is the instability of mature nad5 rather than nad5T1 causing loss of the full-length nad5 transcript, and degradation of nad5 losing both translation start and stop codons is enriched in the mutant. Our data imply the assembly of mature nad5 mRNA precedes the protection of PPR78.展开更多
三角状五肽重复(pentatricopeptide repeat,PPR)蛋白通常包含2~27个串联重复的结构域,每个结构域含有35个氨基酸残基。PPR蛋白是一类广泛存在于真核生物体内的RNA结合蛋白,对单链RNA具有序列特异性识别模式,与RNA的转录、剪切、编辑、...三角状五肽重复(pentatricopeptide repeat,PPR)蛋白通常包含2~27个串联重复的结构域,每个结构域含有35个氨基酸残基。PPR蛋白是一类广泛存在于真核生物体内的RNA结合蛋白,对单链RNA具有序列特异性识别模式,与RNA的转录、剪切、编辑、稳定性及翻译等过程密切相关。迄今为止,在哺乳动物中仅发现7个PPR蛋白,它们均存在于线粒体中,包括线粒体RNA聚合酶(mitochondrial RNA polymerase,POLRMT)、富含亮氨酸的三角状五肽重复结构蛋白(leucinerich pentatricopeptide repeat-containing protein,LRPPRC)蛋白、线粒体核糖体小亚基蛋白27(mitochondrial ribosomal protein of the small subunit 27,MRPS27)、线粒体核糖核酸酶P蛋白3(mitochondrial RNase P protein 3,MRPP3)以及五肽重复结构域蛋白(pentaricopeptide repeat domain protein,PTCD)1~3。哺乳动物PPR蛋白家族的成员在线粒体转录、RNA代谢和翻译中具有多种调控作用,对于线粒体功能和细胞健康至关重要。本文简要概述了哺乳动物细胞中PPR蛋白家族7个成员的结构和亚细胞定位,探讨了PPR蛋白在线粒体基因表达调控中的作用,并展望了PPR蛋白对人类线粒体相关疾病的应用前景。展开更多
细胞质雄性不育(cytoplasmic male sterility,CMS)在植物杂交育种中广为应用,其发生与线粒体中的CMS基因有着密切关系。但是由于线粒体基因敲除或下调表达技术手段十分有限,各种作物中大量鉴定出的CMS基因都未能进行功能验证。拟南芥(Ar...细胞质雄性不育(cytoplasmic male sterility,CMS)在植物杂交育种中广为应用,其发生与线粒体中的CMS基因有着密切关系。但是由于线粒体基因敲除或下调表达技术手段十分有限,各种作物中大量鉴定出的CMS基因都未能进行功能验证。拟南芥(Arabidopsis thaliana)线粒体RPF(RNA processing factor)蛋白属于PPR(pentatricopeptide repeat)蛋白家族中的P亚类,由6~8个PPR重复基序组成。每个PPR基序含有35个氨基酸,其第5位和第35位氨基酸对于识别线粒体靶向RNA的一个碱基起到关键作用,由此建立了"PPR密码"规则。拟南芥RPF蛋白以序列识别的方式结合并加工线粒体RNA转录本的5′末端,但目前尚不清楚该加工过程的具体细节及其生理功能。本文综述了RPF蛋白编码基因RPF1~RPF7的鉴定及其功能分析,以及利用人工设计的RPF2蛋白使线粒体基因nad6下调表达的研究进展。植物线粒体RPF蛋白编码基因的鉴定及其功能和应用,对于阐明线粒体mRNA 5′末端加工的分子机制,以及利用反向遗传学手段研究线粒体基因功能,具有重要的科学意义和应用前景。展开更多
文摘Pentatricopepetide repeat （PPR） proteins are a large family of RNA-binding proteins involved in RNA meta- bolism in plant organelles. Although many PPR proteins have been functionally studied, few of them are identified with a function in mitochondrial RNA stability. By using a reverse genetic approach, we characterized the role of the mitochondrion-targeted PPR78 protein in nad5 mature mRNA stability and maize （Zea mays） seed development. Loss of PPR78 function leads to a dramatic reduction in the steady-state level of mitochondrial nad5 mature mRNA, blocks the assembly of complex I in the electron transport chain, and causes an arrest in embryogenesis and endosperm development. Characterization of a second strong allele confirms the function of PPR78 in nad5 mRNA accumulation and maize seed development. The generation of mature nad5 requires the assembly of three distinct precursor RNAs via transsplicing reactions, and the accumulation ofnad5T1 precursor is reduced in the ppr78 mutants. However, it is the instability of mature nad5 rather than nad5T1 causing loss of the full-length nad5 transcript, and degradation of nad5 losing both translation start and stop codons is enriched in the mutant. Our data imply the assembly of mature nad5 mRNA precedes the protection of PPR78.
文摘三角状五肽重复(pentatricopeptide repeat,PPR)蛋白通常包含2~27个串联重复的结构域,每个结构域含有35个氨基酸残基。PPR蛋白是一类广泛存在于真核生物体内的RNA结合蛋白,对单链RNA具有序列特异性识别模式,与RNA的转录、剪切、编辑、稳定性及翻译等过程密切相关。迄今为止,在哺乳动物中仅发现7个PPR蛋白,它们均存在于线粒体中,包括线粒体RNA聚合酶(mitochondrial RNA polymerase,POLRMT)、富含亮氨酸的三角状五肽重复结构蛋白(leucinerich pentatricopeptide repeat-containing protein,LRPPRC)蛋白、线粒体核糖体小亚基蛋白27(mitochondrial ribosomal protein of the small subunit 27,MRPS27)、线粒体核糖核酸酶P蛋白3(mitochondrial RNase P protein 3,MRPP3)以及五肽重复结构域蛋白(pentaricopeptide repeat domain protein,PTCD)1~3。哺乳动物PPR蛋白家族的成员在线粒体转录、RNA代谢和翻译中具有多种调控作用,对于线粒体功能和细胞健康至关重要。本文简要概述了哺乳动物细胞中PPR蛋白家族7个成员的结构和亚细胞定位,探讨了PPR蛋白在线粒体基因表达调控中的作用,并展望了PPR蛋白对人类线粒体相关疾病的应用前景。
