Adaptor Proteins Recruit DRP1 into Helical Assemblies on Mitochondria: Insights from Super-Resolution Imaging

Dynamin-related protein 1 (DRP1) plays a critical role in mitochondrial fission by hydrolyzing GTP to provide energy, and DRP1 relies on adaptor proteins such as MID49/51 and MFF for its recruitment to fission sites on the outer mitochondrial membrane (OMM). Although cryo-electron microscopy has revealed that MID49 and DRP1 can form helical structures in vitro, their structural organization within cells remains unclear. We visualized and statistically characterized the architecture of DRP1 complexes on the OMM in cells by single-molecule localization microscopy (SMLM). These complexes form highly dynamic structures with diameters ranging from 200 to 400 nm and an average pitch of approximately 160 nm, which varies depending on the adaptor protein involved. Furthermore, we investigated the relationship between the adaptor proteins to explain how DRP1 complex assembly influences mitochondrial morphology. Based on our findings, we propose a model for DRP1 complex assembly during mitochondrial fission. Our study offers new insights into the molecular mechanisms regulating mitochondrial fission and provides assistance for research on related diseases.