Structural basis of mitochondrial receptor binding and constriction by DRP1

Abstract

Summary Mitochondrial inheritance, genome maintenance, and metabolic adaptation depend on organelle fission by Dynamin-Related Protein 1 (DRP1) and its mitochondrial receptors. DRP1 receptors include the paralogs Mitochondrial Dynamics 49 and 51 (MID49/MID51) and Mitochondrial Fission Factor (MFF), but the mechanisms by which these proteins recruit and regulate DRP1 are unknown. Here we present a cryoEM structure of human, full-length DRP1 coassembled with MID49 and an analysis of structure- and disease-based mutations. We report that GTP induces a remarkable elongation and rotation of the G-domain, Bundle-Signaling Element (BSE) and connecting hinge loops of DRP1. In this conformation, a network of multivalent interactions promotes polymerization of a linear DRP1 filament with MID49/MID51. Following coassembly, GTP hydrolysis and exchange lead to MID receptor dissociation, filament shortening and curling of DRP1 oligomers into constricted and closed rings. Together, these views of full-length, receptor- and nucleotide-bound conformations reveal how DRP1 performs mechanical work through nucleotide-driven allostery.

The structural biology of the dynamin‐related proteins: New insights into a diverse, multitalented family

“…Long‐range helical imperfections also limit the useable information in the power spectrum of the helix, leading to difficulties in indexing, which is a necessary step in generating initial models for the iterative reconstruction, though some brute‐force real‐space search procedures have been successful in identifying helical parameters. The results of these advances and others are that near‐atomic‐resolution reconstructions of lipid‐ and GMPPCP‐bound human dynamin 1 ΔPRD (3.75 å; Figure B), Drp1‐MiD49 co‐filaments (4.2 å; Figure D) and MxB polymers (4.6 å; Figure A) have recently been achieved by cryo‐EM. These models have supported the generation and refinement of detailed atomic models for how the DRPs assemble to generate their respective higher order assemblies.…”

“…Furthermore, Drp1 G362D, which harbors a mutation within Stalk Loop 1, thereby disrupting Interface 3, assembles into closed rings. In the presence of GMPPCP, stable rings were obtained of this mutant, which permitted the reconstruction of the predominant, 12‐membered form . In this case, Interface 2 was, indeed, conserved in conformation but extensive tilting at Interfaces 1 and 3 was observed to account for the turn between adjacent dimers.…”

“…In mammalian cells, proteins anchored in the mitochondrial outer membrane, such as MFF (mitochondrial fission factor) and the related adaptors MiD49 and MiD51 (mitochondrial dynamics), act in this capacity . Co‐filaments formed with MiD49 and Drp1 in the presence of GTP or GMPPCP display a unique linear morphology that is distinct from other Drp1 assembles (Figures D and B) . In this arrangement, Drp1 subunits associate with each other via the same three Stalk interfaces that stabilize the crystal packing of the dimeric dynamins, but each Drp1 monomer, additionally, contacts four independent MiD49 molecules.…”

“…The geometry of the interactions is such that MiD49 can only engage adjacent Drp1 G domains via its DRR (Drp1 recruitment region) when the BSEs are in the open conformation, as is the case in GTP‐ or GMPPCP‐bound Drp1. Addition of GTP triggers disassembly of these co‐filaments and promotes the formation of short, curved filaments that close into rings, consisting only of Drp1, in a time‐dependent manner . Perhaps adjacent linear filaments on the mitochondrial surface stimulate GTP hydrolysis by lateral formation of G‐G dimers, with the resulting buckling of the filaments initiating Drp1‐mediated constriction (Box ).…”

Mitochondrial integrity in neurodegeneration

“…However, although they are able to recruit drp1, it was found that the MiD receptors dissociate from the OMM during GTPase hydrolysis. It was discovered that overexpressing the MiD receptors can prevent mitochondrial fission . Fis1 is a protein first found to interact with the drp1 orthologue, Dnm1, in yeast, however, it was discovered that the interaction was not directly between drp1 and Dnm1, but rather through two adaptor molecules, Mdv1 and Caf4 .…”