线粒体生物生成需从细胞质导入千余种不同蛋白和数种非编码RNA。这些生物大分子进入线粒体时遇到的第一道物理屏障是线粒体外膜。外膜中镶嵌的beta-桶蛋白形成跨膜通道，是这些生物大分子进入线粒体的重要渠道。申请人的前期研究揭示了线粒体beta-桶膜蛋白生物生成的机理，并初步分析了以Tom40、VDAC为代表的beta-桶膜蛋白N端结构域与beta-桶的相互作用。本课题将以酿酒酵母和人细胞系为模型，深入研究线粒体beta-桶膜蛋白N端结构域与其自身beta-桶相互作用的功能，建立捕获非编码RNA跨膜转运中间体的新方法，鉴定可能参与非编码RNA跨膜转运的未知膜蛋白。由此，本课题将揭示线粒体beta-桶膜蛋白调控生物大分子跨膜转运的分子机制，阐明线粒体生物生成过程中蛋白质和RNA跨膜转运的共性与不同，为进一步揭示线粒体相关疾病的致病机理以及今后设计线粒体靶向的具有治疗功效的RNA提供理论基础。

The biogenesis of mitochondria needs to import ~1000 different proteins and some non-coding RNAs from cytosol. To be imported into mitochondria, the first physical barrier hindering these biological macromolecules is the mitochondrial outer membrane. The beta-barrel membrane proteins set channels within the outer membrane for the transport of these macromolecules. The previous research of the applicant revealed mechanisms governing mitochondrial beta-barrel protein biogenesis and analyzed the intramolecular N-terminus/beta-barrel interaction of beta-barrel proteins Tom40 (protein-conducting channel) and VDAC (metabolites channel). The current research proposal will use baker’s yeast and cultured human cells as models to further study the function of interactions between the N-termini and beta-barrel formed channels, establish new methods to capture the translocation intermediates of non-coding RNAs, identify potential novel membrane components involved in RNA import and uncover the molecular mechanisms regarding how mitochondrial beta-barrels regulate the translocation of various biomacromolecules across the outer membrane. This work will shed important light on the general principles and differences of the translocation of protein versus RNA across membrane during mitochondrial biogenesis, and also lay important ground for further understanding the mechanisms underlying mitochondrial diseases and for designing mitochondria-targeted therapeutic RNA to treat mitochondrial DNA diseases.