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Dynamins combine mechano-constriction and membrane remodeling to enable two-step mitochondrial fission via a

Haleh Alimohamadi1,2,3,4, Elizabeth Wei-Chia Luo1,2,3,4, Rena Yang1,2,3,4

  • 1Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA 90025, USA.

Biorxiv : the Preprint Server for Biology
|September 4, 2024
PubMed

Insights

Mitochondrial fission relies on dynamin proteins. This study reveals how dynamin assembly and disassembly synergistically drive membrane scission through a mechanical model, impacting disease understanding.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Biophysics

Background:

  • Mitochondrial fission is crucial for cellular function and is regulated by dynamin proteins.
  • Dysregulation of dynamin proteins is linked to various human diseases.
  • Dynamins act as GTP hydrolysis-driven mechanoenzymes, forming helical structures to constrict membranes.

Purpose of the Study:

  • To investigate the synergistic mechanisms by which dynamins influence membrane shape during fission.
  • To elucidate the role of negative Gaussian curvature in completing the fission process.
  • To understand how dynamin assembly and disassembly contribute to diverse scission pathways.

Main Methods:

  • Development of a mechanical model for dynamin-membrane interactions.
  • Calibration of the model using small-angle X-ray scattering (SAXS) structural data.
  • Analysis of membrane shape transitions induced by free and oligomerized dynamin.

Main Results:

  • Free dynamin can induce a 'snap-through instability' in confined membranes.
  • This instability drives a shape transition from a cylindrical membrane to a narrower catenoid neck.
  • The process is critically dependent on the length of the confined membrane tube.
  • Dynamin's ability to induce negative Gaussian curvature is key to fission.

Conclusions:

  • Dynamin's distinct mechanisms, including inducing negative Gaussian curvature, work synergistically to drive mitochondrial fission.
  • Both dynamin assembly and disassembly play paradoxical roles in achieving membrane scission.
  • Understanding these mechanisms provides insights into disease pathologies linked to dynamin dysregulation.

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