Mitochondrial nucleoid condensates drive peripheral fission through high membrane curvature

Mitochondria are dynamic organelles that undergo fusion and fission events, in which the mitochondrial membrane and DNA (mtDNA) play critical roles. The spatiotemporal organization of mtDNA reflects and impacts mitochondrial dynamics. Herein, to study the detailed dynamics of mitochondrial membrane and mtDNA, we rationally develop a dual-color fluorescent probe, mtGLP, that could be used for simultaneously monitoring mitochondrial membrane and mtDNA dynamics via separate color outputs. By combining mtGLP with structured illumination microscopy to monitor mitochondrial dynamics, we discover the formation of nucleoid condensates in damaged mitochondria. We further reveal that nucleoid condensates promoted the peripheral fission of damaged mitochondria via asymmetric segregation. Through simulations, we find that the peripheral fission events occurred when the nucleoid condensates interacted with the highly curved membrane regions at the two ends of the mitochondria. Overall, we show that mitochondrial nucleoid condensates utilize peripheral fission to maintain mitochondrial homeostasis. [Display omitted] •mtGLP simultaneously labels mitochondrial membrane and mtDNA in living cells•Mitochondrial damage results in nucleoid condensates•Nucleoid condensates are associated with peripheral fission of mitochondria•Nucleoid condensates drive peripheral fission through high membrane curvature Chen et al. introduce mtGLP, a dual-labeling probe capable of dual monitoring of mitochondrial lipid (blue fluorescence) and mtDNA (green fluorescence), uncovering the role of mitochondrial nucleoid condensates in driving peripheral fission through high membrane curvature.