Ling Qihua, Jarvis Paul
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
Biochim Biophys Acta. 2015 Sep;1847(9):939-48. doi: 10.1016/j.bbabio.2015.02.017. Epub 2015 Mar 8.
Plastids, such as chloroplasts, are widely distributed endosymbiotic organelles in plants and algae. Apart from their well-known functions in photosynthesis, they have roles in processes as diverse as signal sensing, fruit ripening, and seed development. As most plastid proteins are produced in the cytosol, plastids have developed dedicated translocon machineries for protein import, comprising the TOC (translocon at the outer envelope membrane of chloroplasts) and TIC (translocon at the inner envelope membrane of chloroplasts) complexes. Multiple lines of evidence reveal that protein import via the TOC complex is actively regulated, based on the specific interplay between distinct receptor isoforms and diverse client proteins. In this review, we summarize recent advances in our understanding of protein import regulation, particularly in relation to control by the ubiquitin-proteasome system (UPS), and how such regulation changes plastid development. The diversity of plastid import receptors (and of corresponding preprotein substrates) has a determining role in plastid differentiation and interconversion. The controllable turnover of TOC components by the UPS influences the developmental fate of plastids, which is fundamentally linked to plant development. Understanding the mechanisms by which plastid protein import is controlled is critical to the development of breakthrough approaches to increase the yield, quality and stress tolerance of important crop plants, which are highly dependent on plastid development. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
质体，如叶绿体，是植物和藻类中广泛分布的内共生细胞器。除了在光合作用中众所周知的功能外，它们还在信号感知、果实成熟和种子发育等多种过程中发挥作用。由于大多数质体蛋白是在细胞质中产生的，质体已经进化出专门的转运体机制用于蛋白质输入，包括TOC（叶绿体被膜外膜转运体）和TIC（叶绿体被膜内膜转运体）复合体。多条证据表明，基于不同受体异构体和多种底物蛋白之间的特定相互作用，通过TOC复合体的蛋白质输入受到积极调控。在这篇综述中，我们总结了我们对蛋白质输入调控理解的最新进展，特别是与泛素-蛋白酶体系统（UPS）的控制相关的方面，以及这种调控如何改变质体发育。质体输入受体（以及相应的前体蛋白底物）的多样性在质体分化和相互转化中起决定性作用。UPS对TOC组分的可控周转影响质体的发育命运，而这与植物发育有着根本联系。了解质体蛋白输入的控制机制对于开发突破性方法以提高高度依赖质体发育的重要农作物的产量、品质和胁迫耐受性至关重要。本文是名为：叶绿体生物发生的特刊的一部分。
