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IM30 IDPs form a membrane-protective carpet upon super-complex disassembly

Benedikt Junglas1, Roberto Orru2, Amelie Axt3,4

  • 1Department of Chemistry, Biochemistry, Johannes Gutenberg University Mainz, 55128, Mainz, Germany.

Communications Biology
|October 22, 2020
PubMed

Insights

Inner membrane protein IM30 (phage shock protein A family) stabilizes stressed membranes by disassembling into a protective protein carpet. This reveals a new mechanism for membrane stabilization by intrinsically disordered proteins.

Area of Science:

  • Cellular biology
  • Membrane biophysics
  • Protein structure and function

Background:

  • Phage shock protein A (PspA) family proteins, including IM30, are implicated in stabilizing cellular membranes under stress.
  • IM30 is crucial for thylakoid membrane biogenesis and remodeling in chloroplasts and cyanobacteria.
  • The precise mechanism by which PspA and IM30 stabilize membranes remains unclear.

Purpose of the Study:

  • To elucidate the structural mechanism underlying IM30-mediated membrane stabilization.
  • To investigate the in vivo observed IM30 assemblies at membranes.

Main Methods:

  • In vitro structural analysis of IM30 super-complexes.
  • Observation of IM30 behavior on lipid membranes.
  • Correlation of structural findings with in vivo observations.

Main Results:

  • Ring-shaped IM30 super-complexes disassemble upon membrane interaction.
  • Dissociation leads to the formation of a membrane-protecting protein carpet.
  • The C-terminal domain of IM30 unfolds, facilitating protomer self-assembly on membranes.
  • Identified membrane-associated assemblies correspond to previously observed in vivo stress structures.

Conclusions:

  • The study reveals the structural basis for IM30's membrane stabilization function.
  • A novel mechanism of membrane protection via intrinsically disordered protein assembly is highlighted.
  • Findings provide insights into the function of IM30 and related PspA proteins in stress response.

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