Endoplasmic reticulum-assisted mitochondrial precursor biogenesis and quality control

内质网辅助线粒体前体生物发生和质量控制

• 批准号: 10748025
• 负责人: Steven Michael Claypool
• 金额: $ 33.28万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-15 至 2027-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10748025
• 关键词: ATP phosphohydrolase; Biogenesis; Biological Process; Biology; Carboxy-Lyases; Cells; Cellular Stress; Chronology; Client; Complex; Destinations; Detection; Disease; Endoplasmic Reticulum; Excision; Goals; Health; Heat shock proteins; Human; Inner mitochondrial membrane; Knowledge; Life; Link; Lipids; Mediating; Membrane; Mitochondria; Mitochondrial Membrane Protein; Mitochondrial Proteins; Modeling; Molecular; Molecular Chaperones; Nuclear; Organelles; Outer Mitochondrial Membrane; Pathway interactions; Phosphatidylethanolamine; Phosphatidylserines; Phospholipid Metabolism; Phospholipids; Process; Protein Import; Proteins; Publishing; Quality Control; Resolution; Retrieval; Role; Staging; Stress; Surface; System; Testing; Ubiquitin; Yeasts; coping; glycosylation; insight; interest; multicatalytic endopeptidase complex; mutant; novel; operation; protein degradation; trafficking; translocase; virtual

Over the past decade, roles for the endoplasmic reticulum (ER) in the biogenesis of select nuclear-encoded mitochondrial precursors and the degradation of mutant, mis-localized, or non-productively imported proteins from the mitochondrial outer membrane (OM) have begun to emerge. Our interest in this unanticipated, novel ER-associated mitochondrial biology was serendipitous. In our ongoing efforts to characterize the lipid substrate trafficking requirements for phosphatidylserine (PS) decarboxylase 1 (Psd1 in yeast, PISD in humans), an evolutionarily conserved, integral inner mitochondrial membrane protein that produces phosphatidylethanolamine (PE), it became a priority for us to independently ascertain if a small fraction of wild type (WT) Psd1 is glycosylated and thus targeted to the endomembrane system, as recently claimed. Our generated results support the unavoidable conclusion that in yeast, the vast majority, if not all, of functional Psd1 is mitochondrially localized. However, we did uncover an intimate relationship between Psd1 and the ER: unlike the WT protein, non-functional forms of Psd1 are dually localized to the ER, where they are glycosylated, ubiquitinated, and rapidly degraded. Given the role of the ER as a staging ground for the efficient removal of non-functional Psd1, we then asked two questions ― 1) Is Psd1 biogenesis supported by a recently discovered Djp1-mediated Endoplasmic Reticulum Surface Retrieval pathway (ER-SURF)? and 2) Does the accumulation of ER-associated non-functional Psd1 depend on Msp1, an outer mitochondrial membrane resident AAA-ATPase known to remove mis-targeted proteins and non-productively imported mitochondrial precursors from the outer membrane? The resulting answers establish the premise for our proposed aims and identify Psd1 as an ideal model substrate to define novel mechanisms of ER-SURF and protein degradation that will undoubtedly apply to other mitochondrial proteins. The goal of Aim 1 is to define the early, pre- mitochondrial steps of Psd1 biogenesis that are mediated by specific interactions that occur at the ER. Other than a critical role for the Hsp40 cochaperone, Djp1, virtually nothing is known about ER-SURF. Results from Aim 1 will provide mechanistic insight about mitochondrial targeting through this novel pathway and whether it can be coerced in specific contexts to support non-mitochondrial biology. Over the past seven years, it has become increasingly appreciated that the accumulation of mitochondrial precursors outside of this organelle activates a range of cellular stress responses. In this context, our discovery that non-functional mutant Psd1 temporarily associates with ER membranes prior to being degraded is particularly exciting. The goal of Aim 2 is to determine the molecular mechanisms of non-functional Psd1 resolution. Results from Aim 2 will transform our understanding of how cells cope with mitochondrial precursors that fail to reach their correct destination, an emerging focus in the field.

在过去的十年中，内质网（ER）在精选核编码的生物发生中的作用 线粒体前体和突变体，未定位或非生产性进口蛋白的降解 从线粒体外膜（OM）开始出现。我们对这个意想不到的新颖的兴趣 与ER相关的线粒体生物学是偶然的。在我们为表征脂质的努力中 磷脂酰丝氨酸（PS）脱羧酶1的底物运输要求（酵母中的PSD1，PISD，in 人类），一种进化保守的整体内部线粒体膜蛋白，产生 磷脂酰乙醇胺（PE），它是我们独立确定是否一小部分野生的优先事项 如最近所说，类型（WT）PSD1是糖基化的，因此针对内膜系统。我们的 生成的结果支持了不可避免的结论，即在酵母中，绝大多数（如果不是全部）功能 PSD1是线粒体定位的。但是，我们确实发现了PSD1与ER之间的亲密关系： 与WT蛋白不同，PSD1的非功能形式被双重定位于ER，它们是它们 糖基化，泛素化并迅速降解。鉴于ER作为有效效率的阶段地面的作用 删除非功能PSD1，然后我们问了两个问题-1）是PSD1生物发生，最近支持 发现了DJP1介导的内美源网表面检索途径（ER-SURF）？ 2） ER相关的非功能PSD1的积累取决于MSP1，即线粒体外膜 居民AAA-ATPase已知可以去除靶向错误的蛋白质和非生产性进口线粒体 外膜的前体？由此产生的答案为我们拟议的目标建立了前提和 将PSD1识别为理想的模型底物，以定义ER-SURF和蛋白质降解的新机制 毫无疑问，这将适用于其他线粒体蛋白。目标1的目的是定义早期的 PSD1生物发生的线粒体步骤是由ER处发生的特定相互作用介导的。其他 与HSP40同事DJP1相比，关于ER-SURF的关键作用几乎一无所知。结果 AIM 1将提供有关线粒体靶向通过这一新颖途径的机械洞察力以及是否 可以在特定情况下强迫以支持非线粒体生物学。在过去的七年中，它有 越来越多地赞赏线粒体前体在该细胞器之外的积累 激活一系列细胞应力反应。在这种情况下，我们发现非功能突变体PSD1 在降解之前，临时与ER膜的临时关联特别令人兴奋。目标2的目标是 确定非功能PSD1分辨率的分子机制。 AIM 2的结果将变换 我们对细胞如何应对未能达到其正确目的地的线粒体前体的理解，一个 在该领域的新兴重点。