IMPACTING MITOCHONDRIAL FUNCTION THROUGH ALTERED PROTEASE ACTIVITY

摘要 线粒体功能障碍是几乎所有急性淋巴细胞白血病发病和发病的病理标志 神经退行性疾病。决定线粒体功能的主要决定因素之一是活性 内膜(IM)酶，包括依赖于ATP的AAA+锌金属蛋白酶YME1L和 AFG3L2和不依赖于ATP的锌金属蛋白酶OMA1。这些蛋白水解酶调节许多不同的 保护线粒体免受病理损伤的线粒体生物学和功能方面。然而， 遗传或环境因素引起的肌动蛋白水解酶活性失衡与 病因多样的疾病的发病机制，包括许多神经退行性疾病。尽管如此， IM蛋白水解酶调节线粒体生物学的分子机制仍然知之甚少。这里, 我们正在应用一种结构驱动的方法来确定IM蛋白酶的分子机制 在健康和疾病的背景下调节线粒体。我们之前解决了第一个高分辨率的 IM AAA+蛋白酶YME1和AFG3L2的结构我们的结构显示这两种蛋白酶 使用保守的核苷酸驱动的交接机制将底物转移到特权的 用于蛋白质分解的蛋白质水解室。令人惊讶的是，我们还发现了YME1和YME1的独特结构特征 AFG3L2整合到这一保守的易位机制中，显著影响蛋白酶活性和 稳定性。在这里，我们假设这些独特的结构差异赋予IM蛋白酶 不同的机械和生物功能对它们对线粒体的调节很重要。致信地址 为此，我们正在结合低温电子显微镜和细胞生物学来确定结构 IM AAA+蛋白水解酶的差异影响其机械力化学循环并使其能够 独特的生物功能。这将为IM AAA+的分子机制提供新的见解 在健康和疾病中，蛋白酶调节线粒体。此外，我们正在利用这两项研究扩展这项研究 功能基因组和结构方法，以建立结构-功能关系，解释 应激激活的ATP非依赖性IM蛋白酶OMA1-a的激活和蛋白水解性 它的失调与许多人类的病理性线粒体功能障碍有关 疾病。通过这些努力，我们将定义IM蛋白酶如何利用不同的结构特征来执行 适当调节线粒体蛋白平衡和功能所需的多种生物学功能。 此外，我们将揭示改变的病理和潜在的治疗意义的新见解。 线粒体IM蛋白在人类疾病中的活性及寻找药物靶点的新机会 肌动蛋白水解酶用于缓解与许多神经退行性疾病相关的线粒体功能障碍。

SUMMARY Mitochondrial dysfunction is a pathologic hallmark in the onset and pathogenesis of nearly all neurodegenerative diseases. One of the primary determinants in dictating mitochondrial function is the activity of inner membrane (IM) proteases including the ATP-dependent AAA+ zinc metalloproteases YME1L and AFG3L2 and the ATP-independent zinc metalloprotease OMA1. These proteases regulate many different aspects of mitochondrial biology and function to protect mitochondria from pathologic insults. However, imbalances in the activity of IM proteases induced by genetic or environmental factors are implicated in the pathogenesis of etiologically-diverse diseases including many neurodegenerative disorders. Despite this, the molecular mechanisms by which IM proteases regulate mitochondrial biology remain poorly understood. Here, we are applying a structure-driven approach to determine the molecular mechanisms by which IM proteases regulate mitochondria in the context of health and disease. We previously solved the first high-resolution structures of the IM AAA+ proteases YME1 and AFG3L2. Our structures showed that these two proteases employ a conserved nucleotide-driven, hand-over-hand mechanism to translocate substrates into a privileged proteolytic chamber for proteolysis. Surprisingly, we also identified unique structural features of YME1 and AFG3L2 that integrate into this conserved translocation mechanism to distinctly influence protease activity and stability. Here, we hypothesize that these unique structural differences endow IM proteases with different mechanistic and biologic functions important for their regulation of mitochondria. To address this, we are using a combination of cryo-electron microscopy and cell biology to determine how structural differences in IM AAA+ proteases influence their mechanochemical cycle and enable proteases to perform distinct biological functions. This will reveal new insights into the molecular mechanisms by which IM AAA+ proteases regulate mitochondria in health and disease. Furthermore, we are extending this study utilizing both functional genomic and structural approaches to establish a structure-function relationship that explains the activation and proteolytic activity of the ATP-independent, stress-activated IM protease OMA1 – a protease whose dysregulation is implicated in the pathologic mitochondrial dysfunction associated with many human diseases. Through these efforts, we will define how IM proteases utilize distinct structural features to perform the myriad of biological functions required for the proper regulation of mitochondrial proteostasis and function. Furthermore, we will reveal new insights into the pathologic and potentially therapeutic implications of altered mitochondrial IM protease activity in human disease and identify new opportunities to pharmacologically target IM proteases to mitigate mitochondrial dysfunction associated with many neurodegenerative disorders.