Koszela Joanna, Rintala-Dempsey Anne, Salzano Giulia, Pimenta Viveka, Kamarainen Outi, Gabrielsen Mads, Parui Aasna L, Shaw Gary S, Walden Helen
School of Molecular Biosciences, University of Glasgow, Glasgow, UK.
Department of Biochemistry, The University of Western Ontario, London, ON, Canada.
bioRxiv. 2024 Jun 3:2024.06.03.597144. doi: 10.1101/2024.06.03.597144.
Mutations in the gene encoding for the E3 ubiquitin ligase Parkin have been linked to early-onset Parkinson's disease. Besides many other cellular roles, Parkin is involved in clearance of damaged mitochondria via mitophagy - a process of particular importance in dopaminergic neurons. Upon mitochondrial damage, Parkin accumulates at the outer mitochondrial membrane and is activated, leading to ubiquitination of many mitochondrial substrates and recruitment of mitophagy effectors. While the activation mechanisms of autoinhibited Parkin have been extensively studied, it remains unknown how Parkin recognises its substrates for ubiquitination, and no substrate interaction site in Parkin has been reported. Here, we identify a conserved region in the flexible linker between the Ubl and RING0 domains of Parkin, which is indispensable for Parkin interaction with the mitochondrial GTPase Miro1. Our results explain the preferential targeting and ubiquitination of Miro1 by Parkin and provide a biochemical explanation for the presence of Parkin at the mitochondrial membrane prior to activation induced by mitochondrial damage. Our findings are important for understanding mitochondrial homeostasis and may inspire new therapeutic avenues for Parkinson's disease.
编码E3泛素连接酶帕金（Parkin）的基因突变与早发性帕金森病有关。除了许多其他细胞功能外，帕金还通过线粒体自噬参与清除受损线粒体，这一过程在多巴胺能神经元中尤为重要。线粒体受损时，帕金会在线粒体外膜聚集并被激活，导致许多线粒体底物发生泛素化，并招募线粒体自噬效应器。虽然对自抑制状态的帕金的激活机制已进行了广泛研究，但帕金如何识别其泛素化底物仍不清楚，且尚未有关于帕金中底物相互作用位点的报道。在此，我们在帕金的泛素样结构域（Ubl）和RING0结构域之间的柔性连接区鉴定出一个保守区域，该区域对于帕金与线粒体GTP酶米罗1（Miro1）的相互作用必不可少。我们的结果解释了帕金对Miro1的优先靶向和泛素化，并为线粒体损伤诱导激活之前帕金在线粒体外膜的存在提供了生化解释。我们的发现对于理解线粒体稳态很重要，可能会为帕金森病带来新的治疗途径。
