Allosteric Mechanisms and Regulation of Drp1-catalyzed Mitochondrial Fission

Mitochondria are dynamic organelles that undergo cycles of division and fusion. Mitochondrial division (MD) is essential for mitochondrial quality control, transport, distribution, and inheritance. Defects in MD underlie various neurological disorders, including Alzheimer’s, Parkinson’s, and Huntington’s diseases, as well as cardiovascular disease and cancer. While the mechanochemical GTPase dynamin-related protein 1 (Drp1) is key to MD, the molecular mechanisms governing Drp1 function in mitochondrial membrane remodeling remain poorly understood. Recent studies indicate that Drp1 is both structurally and functionally autoinhibited, necessitating an essential role for binding partners in alleviating this autoinhibition. Here, we will investigate the distinct allosteric nodes of functional control exercised by the protein partners GIPC1, MiD51, and Dynamin 2 (Dyn2) on Drp1-catalyzed MD. This grant application aims to address several unknown fundamental issues essential for understanding Drp1-catalyzed MD. These include: 1) understanding the structural basis and mechanism of autoinhibition by the intrinsically disordered Drp1 C-terminal Short Linear Motif, and its alleviation by GIPC1, 2) investigating the mechanisms involved in the MiD51-directed conformational transition of Drp1 from the autoinhibited form in solution to the assembly-competent form on membranes, including the role of the putative interface-4 in MiD51-directed Drp1 co-assembly, and 3) studying the mechanisms of Dyn2 in regulating Drp1 assembly-disassembly dynamics on membranes to improve membrane fission efficacy. We will combine mutagenesis and X-ray crystallography with cutting-edge cryo-EM, and multiple independent fluorescence spectroscopic and imaging techniques to address these aims. Successful outcomes of this research project will provide (i) a fundamentally improved understanding of the mechanisms underlying Drp1-catalyzed MD, and (ii) a molecular foundation for the design of drugs and therapeutics that can beneficially modulate MD in various diseased states. Project Number: 1R01GM160378-01A1 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of General Medical Sciences (NIGMS) | Principal Investigator: Rajesh Ramachandran | Institution: CASE WESTERN RESERVE UNIVERSITY, CLEVELAND, OH | Award Amount: $461,355 | Activity Code: R01 | Study Section: Biochemistry and Biophysics of Membranes Study Section[BBM] View on NIH RePORTER: https://reporter.nih.gov/project-details/11366096