Unorthodox information processing systems in mitochondria

线粒体内非常规信息处理系统：拼图基因的转录本是真核细胞不可或缺的一部分，为其提供能量和氨基酸、核苷酸等分子构件。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。虽然现存真核物种中的线粒体起源于同一细菌祖先，但随着时间的推移，它们已经发生了实质性的变化和多样化，这就是为什么将线粒体称为大自然的进化游乐场的原因。我们的总体研究计划试图阐明线粒体是如何发挥作用的：从遗传信息的存储到转录基因调控、RNA处理和蛋白质合成。还有很多东西有待发现，特别是在微生物真核生物中，这些微生物基本上还没有被探索。到目前为止所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。我们的五年研究计划旨在调查我们在一组海洋原生动物-双线虫中发现的最古怪的线粒体。它们的基因被系统地碎片化，基因片段被单独转录，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本的成熟(绝对不同于传统的内含子剪接)以前从未报道过。问题是，在模式物种乳头藻中，RNA片段的配对和连接到底是如何实现的。我们的假设是：匹配是由蛋白质保证的；片段由最近发现的RtcB类型的RNA连接酶缝合在一起；这些组件是假设的线粒体‘关节小体’复合体的一部分。白纹藻的核基因组包含三个不同的RtcB基因(DP-RtcB1、2、3)。为了揭示它们的功能，拟议的研究有以下目的和目标：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。通过研究催化活性和底物偏好来鉴定假定的线粒体关节小体。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：洞察(I)假设的连接体的组成，(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。这样的项目将加强加拿大对基础研究领域的贡献--这是所有创新的基础。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，从环境到人类健康都有很好的应用前景。

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.