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Updated: Sep 10, 2025

Reconstitution of Msp1 Extraction Activity with Fully Purified Components
05:52

Reconstitution of Msp1 Extraction Activity with Fully Purified Components

Published on: August 10, 2021

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Lipid bilayer properties govern substrate engagement and extraction by the AAA+ ATPase Msp1

Heidi L Fresenius1, Brian Acquaviva2, Deepika Gaur3

  • 1Department of Chemistry & Biochemistry, Previously at University of Toledo, Toledo, Ohio, USA.

The Journal of Biological Chemistry
|August 21, 2025
PubMed

Insights

Msp1, an ATPase, removes faulty membrane proteins from mitochondria. It recognizes substrates via hydrophobic mismatch with the lipid bilayer, with TMD extraction being the rate-limiting step in this essential protein quality control process.

Area of Science:

  • Cellular Biology
  • Biochemistry
  • Membrane Protein Biology

Background:

  • Protein quality control is vital for cellular health, involving the removal of aberrant proteins.
  • Failures in membrane protein removal are linked to diseases like cancer and neurodegeneration.
  • Msp1 (ATPases Associated with diverse cellular Activities) is an ATPase crucial for removing mistargeted proteins from the outer mitochondrial membrane.

Purpose of the Study:

  • To elucidate the mechanism by which Msp1 recognizes and extracts substrates from the outer mitochondrial membrane.
  • To investigate the impact of the lipid bilayer environment on Msp1-mediated membrane protein extraction.

Main Methods:

  • Development of a novel, quantitative, and rapid in vitro assay for Msp1 extraction.
  • Systematic modification of model substrates and the lipid environment to test Msp1 activity.
  • Analysis of substrate recognition and extraction kinetics.

Main Results:

  • Msp1 recognizes substrates based on a hydrophobic mismatch between the substrate's transmembrane domain (TMD) and the surrounding lipid bilayer.
  • The rate-limiting step in Msp1's function is the extraction of the substrate's TMD from the lipid bilayer.
  • The developed assay maintains physiological substrate selectivity.

Conclusions:

  • The lipid bilayer composition significantly influences AAA+ ATPase-mediated membrane protein extraction.
  • Hydrophobic mismatch is a key recognition mechanism for Msp1.
  • This study provides fundamental insights into Msp1 function and AAA+ ATPase mechanisms in membrane protein quality control.
Keywords:
ATPase associated with diverse cellular activities (AAA+)lipid bilayermembrane proteinmitochondriaproteostasis

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