Protein targeting to the chloroplast outer membrane and Toc complex assembly and function

真核细胞被细分为许多膜结合的细胞器，这些细胞器为许多生存所不可或缺的生化途径提供专门的环境。植物细胞与大多数其他真核生物的区别在于存在一类称为质体的基本细胞器。最著名的质体是叶绿体，它负责光合作用的反应，这是所有生命所依赖的过程。在每个细胞器中发现的绝大多数蛋白质由细胞核中的基因编码，并在胞质溶胶中翻译。因此，细胞依赖于蛋白质运输系统来确保这些蛋白质被递送到其适当的亚细胞区室。虽然靶向系统已被描述为所有的细胞器，蛋白质识别和易位的机制还没有很好地理解。我的研究计划的长期目标是有助于蛋白质靶向和导入叶绿体的机制的理解，作为所有真核生物中细胞内蛋白质运输和细胞器生物合成的模型，并与植物生长和发育有关。蛋白质进入叶绿体依赖于位于细胞器周围的双膜上的蛋白质复合物。本研究的重点是了解叶绿体蛋白质导入装置是如何在叶绿体表面组装的，以及这些转运子是如何实现蛋白质导入的精确性的。我们将使用分子，生物化学和生物物理方法的组合，以补充体内方法来回答这些问题。具体来说，我们将研究蛋白质是如何靶向叶绿体外膜，如何负责启动输入叶绿体组装复合物，并确定其底物特异性的基础。详细了解蛋白质是如何输入到叶绿体是重要的理解光合作用和植物生长发育。此外，这项工作将有助于我们对细胞内蛋白质运输的全面了解，这是所有生物体生长和生存所必需的基本细胞过程。

Eukaryotic cells are sub-divided into numerous membrane-bound organelles that provide specialized environments for many biochemical pathways that are indispensable for survival. The cells of plants are distinguished from most other eukaryotes by the presence of a class of essential organelles called plastids. The most well-known plastids are chloroplasts, which house the reactions of photosynthesis, a process upon which all life depends. The vast majority of proteins found within each organelle are encoded by genes in the nucleus and are translated in the cytosol. Cells therefore rely on protein trafficking systems to ensure these proteins are delivered to their proper sub-cellular compartment. Although targeting systems have been described for all organelles, the mechanisms of protein recognition and translocation are not well understood. The long-term goal of my research program is to contribute to the understanding of the mechanism of protein targeting and import into chloroplasts, as a model for intracellular protein trafficking and organelle biogenesis in all eukaryotes, and as it pertains to plant growth and development. Protein import into chloroplasts relies on proteinaceous complexes located at the double membrane that surrounds the organelle. The focus of my research program is to understand how the chloroplast protein import apparatus is assembled at the chloroplast surface, and how the precision of protein import is achieved by these translocons. We will use a combination of molecular, biochemical and biophysical approaches to complement in vivo approaches to answer these questions. Specifically, we will investigate how proteins are targeted to the chloroplast outer membrane, how complexes responsible for initiating import into chloroplasts are assembled, and determine the basis for their substrate specificity. Detailed knowledge of how proteins are imported into chloroplasts is important for understanding photosynthesis and plant growth and development. Furthermore, the work will contribute to our overall understanding of intracellular protein trafficking, which is a fundamental cellular process essential for the growth and survival of all organisms.