Localization of translation and non-translated mRNAs; functions, mechanisms and novel compartments

植物和藻类通过光合作用从光中获取生长和繁殖所需的能量。光合作用发生在称为叶绿体的亚细胞细胞器中。我们之前的研究表明，叶绿体中含有用于蛋白质合成和RNA质量控制的室室。我们正在分析这些区室，作为了解细胞器生物发生和质量控制的途径，我们希望揭示细胞生物学的一般原理。这个研究项目的一个目标是了解叶绿体中构成类囊体囊泡的膜是如何形成的。类囊体囊泡进行光合作用的光驱动反应。我们已经确定了一个特殊的区域膜包膜包围叶绿体的蛋白质和叶绿素的类囊体产生。我们首次展示了细胞质的核糖体在与叶绿体直接接触的情况下合成蛋白质。这在大多数其他细胞器中都有，但在叶绿体中没有。对叶绿体包膜中这种新型生物结构域的组成进行表征，将为长期以来关于类囊体膜的发育起源以及它们如何从叶绿体包膜中产生的谜团提供新的见解。另一个目标是表征叶绿体中处理RNA质量控制的隔室。RNA是遗传信息从基因转移到产生功能蛋白的重要分子。叶绿体有自己的基因组和基因表达系统，因为它们是从大约10 - 20亿年前居住在原始植物细胞中的自由生活的光合细菌进化而来的。因此，叶绿体保留了缩小的基因组和基因表达系统，包括RNA。我们发现并研究了一种叫做“叶绿体应激颗粒”的结构，它处理的是刚刚离开蛋白质合成机器、没有被翻译的RNA。这些叶绿体应激颗粒类似于在所有真核细胞中发现的应激颗粒，甚至在被称为应激颗粒的细菌中也发现了应激颗粒。我们将描述叶绿体胁迫颗粒的特征，以了解这种细胞器如何处理RNA质量控制，并希望为所有生物体中的胁迫颗粒功能提供一般见解。总之，这些结果将与加拿大工业生物技术的发展有关，因为藻类在食品工业中被使用，几十年来作为环境污染物的生物传感器。藻类正在被改造以在工业规模上有效地生产高价值分子；例如药品、疫苗和食品补充剂。实现这一潜力将受益于我们关于蛋白质如何在叶绿体中合成的研究成果。研究结果还将有助于提高农业作物生物技术改良所需的基本知识。

Plants and algae obtain energy for growth and reproduction from light using a process called photosynthesis. Photosynthesis occurs in subcellular organelles called chloroplasts. Our previous research revealed that chloroplasts contain compartments for the synthesis of proteins and RNA quality control. We are analyzing these compartments as an avenue to understand biogenesis and quality control in this organelle and, we hope, reveal general principles of Cell Biology. One goal of this research program is to understand how the membranes that make up thylakoid vesicles within chloroplasts are made. Thylakoid vesicles carry out the light-driven reactions of photosynthesis. We have identified a special region of the membranous envelope that encloses the chloroplast where proteins and chlorophyll of the thylakoids are generated. We show for the first time that the ribosomes of the cell's cytoplasm are synthesizing proteins in direct contact with the chloroplast. This has been show for most other organelles, but not for chloroplasts. Characterization of the composition of this novel biogenic domain of the chloroplast envelope will lead to new insights regarding the long-standing mystery regarding the developmental origins of thylakoid membranes and how they arise from the chloroplast envelope. Another goal is to characterize a compartment within the chloroplast that handles quality control of RNA. RNA is an important molecule in the transfer of genetic information from the gene to generate functional proteins. Chloroplasts have their own genome and gene expression system because they evolved from a free-living photosynthetic bacterium which took up residence in the primordial plant cell some 1-2 billion year ago. Since, chloroplasts have retained a downsized genome and gene expression system, including RNA. We identified and study structures are called "chloroplast stress granules" which handle RNA that has just left the protein synthesis machinery and is not being translated. These chloroplast stress granules are similar to stress granules found in all eukaryotic cells examined and even in bacteria called stress granules. We will characterize chloroplast stress granules to learn about how this organelle handles RNA quality control and, we hope, provide general insights into stress granule functions in all organisms. In summary, the results will be relevant to the development of biotechnologies for Canadian industries because algae are used in the food industry and as biosensors for environmental pollutants for decades. Algae are being engineered to efficiently produce high-value molecules at industrial scales; e.g. pharmaceuticals, vaccines, and food supplements. Realization of this potential will benefit from our research results regarding how proteins are synthesized in chloroplasts. The results will also contribute to the basic knowledge that will be required for the biotechnological improvement of crop plants in agriculture.