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Updated: Sep 30, 2025
A Model Membrane Platform for Reconstituting Mitochondrial Membrane Dynamics
Published on: September 2, 2020
Recovery of particulate methane monooxygenase structure and activity in a lipid bilayer
Christopher W Koo1, Frank J Tucci1, Yuan He1
1Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
Abstract:
Bacterial methane oxidation using the enzyme particulate methane monooxygenase (pMMO) contributes to the removal of environmental methane, a potent greenhouse gas. Crystal structures determined using inactive, detergent-solubilized pMMO lack several conserved regions neighboring the proposed active site. We show that reconstituting pMMO in nanodiscs with lipids extracted from the native organism restores methane oxidation activity. Multiple nanodisc-embedded pMMO structures determined by cryo-electron microscopy to 2.14- to 2.46-angstrom resolution reveal the structure of pMMO in a lipid environment. The resulting model includes stabilizing lipids, regions of the PmoA and PmoC subunits not observed in prior structures, and a previously undetected copper-binding site in the PmoC subunit with an adjacent hydrophobic cavity. These structures provide a revised framework for understanding and engineering pMMO function.
Insights
Researchers restored bacterial methane oxidation (pMMO) activity by embedding the enzyme in nanodiscs with native lipids. This revealed pMMO’s structure in a lipid environment, uncovering new details for enzyme engineering.
Area of Science:
- Biochemistry and Structural Biology
- Environmental Microbiology
- Biotechnology
Background:
- Bacterial methane oxidation by particulate methane monooxygenase (pMMO) is crucial for mitigating environmental methane, a potent greenhouse gas.
- Previous crystal structures of pMMO were derived from inactive, detergent-solubilized enzyme, missing key regions near the active site.
Purpose of the Study:
- To determine the high-resolution structure of pMMO within a native lipid environment.
- To understand how lipids influence pMMO structure and activity.
- To provide a revised structural framework for pMMO engineering and function.
Main Methods:
- Reconstitution of pMMO into nanodiscs using lipids from its native organism.
- Cryo-electron microscopy (cryo-EM) to determine high-resolution structures (2.14–2.46 Å).
- Structural analysis to identify stabilizing lipids and novel protein features.
Main Results:
- Reconstitution in nanodiscs restored methane oxidation activity.
- High-resolution cryo-EM structures revealed pMMO within a lipid bilayer.
- The structures identified stabilizing lipids, previously unobserved regions of PmoA and PmoC subunits, and a new copper-binding site in PmoC with an adjacent hydrophobic cavity.
Conclusions:
- The native lipid environment is essential for pMMO structure and function.
- The novel structural features, including the PmoC copper-binding site, offer new insights into the enzyme's catalytic mechanism.
- These findings provide a critical foundation for future engineering efforts to enhance pMMO's efficiency in methane removal.
