Puchades Cristina, Ding Bojian, Song Albert, Wiseman R Luke, Lander Gabriel C, Glynn Steven E
Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA; Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, La Jolla, CA 92037, USA.
Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, USA.
Mol Cell. 2019 Sep 5;75(5):1073-1085.e6. doi: 10.1016/j.molcel.2019.06.016. Epub 2019 Jul 18.
Mitochondrial AAA+ quality-control proteases regulate diverse aspects of mitochondrial biology through specialized protein degradation, but the underlying mechanisms of these enzymes remain poorly defined. The mitochondrial AAA+ protease AFG3L2 is of particular interest, as genetic mutations localized throughout AFG3L2 are linked to diverse neurodegenerative disorders. However, a lack of structural data has limited our understanding of how mutations impact enzymatic function. Here, we used cryoelectron microscopy (cryo-EM) to determine a substrate-bound structure of the catalytic core of human AFG3L2. This structure identifies multiple specialized structural features that integrate with conserved motifs required for ATP-dependent translocation to unfold and degrade targeted proteins. Many disease-relevant mutations localize to these unique structural features of AFG3L2 and distinctly influence its activity and stability. Our results provide a molecular basis for neurological phenotypes associated with different AFG3L2 mutations and establish a structural framework to understand how different members of the AAA+ superfamily achieve specialized biological functions.
线粒体AAA+质量控制蛋白酶通过特定的蛋白质降解作用调节线粒体生物学的多个方面，但其作用机制仍不清楚。线粒体AAA+蛋白酶AFG3L2尤其引人关注，因为AFG3L2基因的突变与多种神经退行性疾病相关。然而，缺乏结构数据限制了我们对突变如何影响酶功能的理解。在这里，我们使用冷冻电子显微镜（cryo-EM）确定了人AFG3L2催化核心与底物结合的结构。该结构确定了多个特殊的结构特征，这些特征与ATP依赖性转运所需的保守基序相结合，以展开和降解目标蛋白。许多与疾病相关的突变定位于AFG3L2的这些独特结构特征上，并明显影响其活性和稳定性。我们的结果为与不同AFG3L2突变相关的神经学表型提供了分子基础，并建立了一个结构框架，以了解AAA+超家族的不同成员如何实现特殊的生物学功能。
