Unorthodox information processing systems in mitochondria

线粒体中的非常规信息处理系统：来自“接合体”修补的拼图基因的转录物线粒体是真核细胞不可分割的一部分，为它提供能量和分子构建模块，如氨基酸和核苷酸。这种细胞器是特殊的，因为它拥有自己的基因组和自己的DNA复制，转录和翻译机制。虽然现存的真核生物物种的线粒体起源于相同的细菌祖先，但随着时间的推移，它们发生了很大的变化和多样化，这就是将线粒体称为自然界进化游乐场的原因。我们的总体研究旨在阐明线粒体是如何运作的：从遗传信息的存储到转录基因调控，RNA加工和蛋白质合成。特别是在微生物真核生物中，还有很多东西有待发现，这些东西在很大程度上尚未探索。到目前为止，研究的少数非模型系统仅提供了对线粒体基因表达的非凡多样性以及潜在的分子机制和机制的一瞥。我们的五年研究提案旨在调查我们在一组海洋原生动物中发现的最偏心的线粒体，diplonemids。它们的基因是系统性片段化的，基因片段单独转录，然后才连接成成熟的信使RNA或核糖体RNA。这种基因结构和转录物成熟（与传统的内含子剪接明显不同）以前从未报道过。问题是在模式种乳头双丝藻中，RNA片段的匹配和连接是如何精确实现的。我们的假设是：配对是由蛋白质保证的;片段是由最近发现的RtcB型RNA连接酶缝合在一起的;这些成分是假定的线粒体“接合体”复合体的一部分。Diplonema核基因组包含三个不同的RtcB基因（Dp-RtcB 1，2，3）。为了揭示其功能，拟议的研究有以下目标和目的： 1.通过确定蛋白质的相互作用伙伴和基因的进化起源来确定Dp-RtcBs的生物学作用。 2.通过研究催化活性和底物偏好来确定假定的线粒体连接体。这些目标将通过结合经典生物化学、基因组学、蛋白质组学和生物信息学的方法来实现。预期结果：深入了解（i）假设的接合体的组成，（ii）这种独特的RNA连接过程的分子机制，以及（iii）导致这种看似不可能的过程的进化路径。像这样的项目将加强加拿大对基础研究的贡献-所有创新的基础。此外，所获得的知识可能会扩大我们的分子工程实验工具箱，从环境到人类健康的应用前景广阔。

Unconventional information processing system in Diplonema mitochondria: transcripts from jigsaw-puzzle genes mended by 'joinosomes' Mitochondria are an integral part of the eukaryotic cell, supplying it with energy and molecular building blocks such as amino acids and nucleotides. This organelle is special because it possesses its own genome and own machineries for DNA replication, transcription, and translation. While mitochondria across extant eukaryotic species originated from the same bacterial ancestor, they have substantially changed and diversified over time, the reason for referring to mitochondria as Nature's evolutionary playground. Our overarching research PROGRAM seeks to elucidate how mitochondria are functioning: from storage of genetic information to transcriptional gene regulation, RNA processing, and protein synthesis. Much remains to be discovered in particular in microbial eukaryotes that are largely unexplored. The few non-model systems investigated so far have provided just a glance at the extraordinary diversity of mitochondrial gene expression and the underlying molecular machineries and mechanisms. Our five-year research PROPOSAL aims at investigating most eccentric mitochondria that we discovered in a group of marine protozoans, the diplonemids. Their genes are systematically fragmented, with gene pieces transcribed separately and only then joined into mature messenger RNAs or ribosomal RNAs. This kind of gene structure and transcript maturation (definitely distinct from conventional intron splicing) has never been reported before. The question is how exactly the matchmaking and joining of RNA pieces is achieved in the type species Diplonema papillatum. Our hypotheses are: matchmaking is assured by proteins; pieces are stitched together by an RNA ligase of the just recently discovered RtcB type; and these components are part of a postulated mitochondrial `joinosome' complex. The Diplonema nuclear genome contains three distinct RtcB genes (Dp-RtcB1, 2, 3). To unravel their function, the proposed research has the following AIMS and OBJECTIVES:    1. Establish the biological roles of Dp-RtcBs by determining the proteins' interaction partners and the genes' evolutionary origins.    2. Identify the postulated mitochondrial joinosomes by investigating catalytic activity and substrate preferences. These aims will be addressed by an APPROACH combining classical biochemistry, genomics, proteomics, and bioinformatics. EXPECTED OUTCOME: insight into (i) the makeup of the postulated joinosomes, (ii) the molecular mechanism of this unique RNA joining process, and (iii) the evolutionary path leading to such a seemingly improbable process. Projects like this will strengthen Canada's contributions to fundamental research --the foundation of all innovation. Further, the gained knowledge will likely expand our experimental tool box for molecular engineering, with promising applications from environment to human health.