A dimeric equilibrium intermediate nucleates Drp1 reassembly on mitochondrial membranes for fission

• Published in: Molecular biology of the cell Vol. 25; no. 12; pp. 1905 - 1915
• Main Authors: Macdonald, Patrick J, Stepanyants, Natalia, Mehrotra, Niharika, Mears, Jason A, Qi, Xin, Sesaki, Hiromi, Ramachandran, Rajesh
• Format: Journal Article
• Language: English
• Published: United States The American Society for Cell Biology 15.06.2014
• Series: A Highlights from
• Subjects: Animals; Cardiolipins - metabolism; Cells, Cultured; GTP Phosphohydrolases - chemistry; GTP Phosphohydrolases - metabolism; GTP Phosphohydrolases - ultrastructure; Humans; Liposomes - chemistry; Mice; Microtubule-Associated Proteins - chemistry; Microtubule-Associated Proteins - metabolism; Microtubule-Associated Proteins - ultrastructure; Mitochondria - physiology; Mitochondrial Dynamics; Mitochondrial Membranes - enzymology; Mitochondrial Membranes - ultrastructure; Mitochondrial Proteins - chemistry; Mitochondrial Proteins - metabolism; Mitochondrial Proteins - ultrastructure; Protein Multimerization; Protein Structure, Quaternary
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.e14-02-0728

The GTPase dynamin-related protein 1 (Drp1) catalyzes mitochondrial division, but the mechanisms remain poorly understood. Much of what is attributed to Drp1's mechanism of action in mitochondrial membrane fission parallels that of prototypical dynamin in endocytic vesicle scission. Unlike the case for dynamin, however, no lipid target for Drp1 activation at the mitochondria has been identified. In addition, the oligomerization properties of Drp1 have not been well established. We show that the mitochondria-specific lipid cardiolipin is a potent stimulator of Drp1 GTPase activity, as well as of membrane tubulation. We establish further that under physiological conditions, Drp1 coexists as two morphologically distinct polymeric species, one nucleotide bound in solution and the other membrane associated, which equilibrate via a dimeric assembly intermediate. With two mutations, C300A and C505A, that shift Drp1 polymerization equilibria in opposite directions, we demonstrate that dimers, and not multimers, potentiate the reassembly and reorganization of Drp1 for mitochondrial membrane remodeling both in vitro and in vivo.