Dynamin-related Protein 1 Oligomerization in Solution Impairs Functional Interactions with Membrane-anchored Mitochondrial Fission Factor

• Published in: The Journal of biological chemistry Vol. 291; no. 1; pp. 478 - 492
• Main Authors: Clinton, Ryan W., Francy, Christopher A., Ramachandran, Rajesh, Qi, Xin, Mears, Jason A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-01-2016; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Cell Biology; dynamin; dynamin-related protein 1; Dynamins - chemistry; Dynamins - metabolism; electron microscopy (EM); GTPase; Liposomes - metabolism; Membrane Proteins - metabolism; membrane remodeling; Mice; mitochondria; Mitochondrial Dynamics; mitochondrial fission; mitochondrial fission factor; Mitochondrial Membranes - metabolism; Mitochondrial Proteins - metabolism; Models, Biological; Mutant Proteins - metabolism; Mutation - genetics; Protein Binding; Protein Multimerization; Protein Structure, Tertiary; protein-protein interaction; Solutions; mitochondrial fission factor; membrane remodeling; mitochondria; dynamin-related protein 1; protein-protein interaction; mitochondrial fission; GTPase; dynamin; electron microscopy (EM)
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M115.680025

Mitochondrial fission is a crucial cellular process mediated by the mechanoenzymatic GTPase, dynamin-related protein 1 (Drp1). During mitochondrial division, Drp1 is recruited from the cytosol to the outer mitochondrial membrane by one, or several, integral membrane proteins. One such Drp1 partner protein, mitochondrial fission factor (Mff), is essential for mitochondrial division, but its mechanism of action remains unexplored. Previous studies have been limited by a weak interaction between Drp1 and Mff in vitro. Through refined in vitro reconstitution approaches and multiple independent assays, we show that removal of the regulatory variable domain (VD) in Drp1 enhances formation of a functional Drp1-Mff copolymer. This protein assembly exhibits greatly stimulated cooperative GTPase activity in solution. Moreover, when Mff was anchored to a lipid template, to mimic a more physiologic environment, significant stimulation of GTPase activity was observed with both WT and ΔVD Drp1. Contrary to recent findings, we show that premature Drp1 self-assembly in solution impairs functional interactions with membrane-anchored Mff. Instead, dimeric Drp1 species are selectively recruited by Mff to initiate assembly of a functional fission complex. Correspondingly, we also found that the coiled-coil motif in Mff is not essential for Drp1 interactions, but rather serves to augment cooperative self-assembly of Drp1 proximal to the membrane. Taken together, our findings provide a mechanism wherein the multimeric states of both Mff and Drp1 regulate their collaborative interaction.