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Modulating Liposome Surface Charge for Maximized ATP Regeneration in Synthetic Nanovesicles.
Sabina Deutschmann1,2, Stefan Theodore Täuber1, Lukas Rimle1,2
1Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, Bern 3012, Switzerland.
ACS Synthetic Biology
|November 26, 2024
Summary
Researchers developed a novel liposome system to study bacterial respiration. This system enhances ATP synthesis rates by 3-fold using natural substrates and precisely orienting respiratory enzymes.
Area of Science:
- Biochemistry
- Membrane Biophysics
- Bioenergetics
Background:
- Reconstructed respiratory chains in liposomes model in vitro enzyme interactions.
- Escherichia coli cytochrome *bo*3 oxidase and ATP synthase drive ATP synthesis via proton motive force (pmf).
- Previous systems used artificial electron donors and mediators.
Purpose of the Study:
- To extend in vitro respiratory chain models using natural electron entry points (Complex II or NDH-2) and long-chain ubiquinones.
- To optimize liposome composition for efficient enzyme activity and proton motive force generation.
- To develop a strategy for unidirectional enzyme orientation and enhanced ATP synthesis.
Main Methods:
- Coreconstitution of cytochrome *bo*3 oxidase and ATP synthase into liposomes.
- Utilizing Complex II or NDH-2 with succinate or NADH as electron sources.
- Employing natural long-chain ubiquinones (Q8, Q10).
- Testing various lipid compositions, including charged and ionizable lipids.
- Developing a pH-dependent liposome fusion strategy for enzyme orientation.
Main Results:
- Negatively charged lipids are essential for NDH-2 activity but reduce pmf and ATP synthesis.
- Positively charged lipids promote desired oxidase orientation but hinder quinone reduction.
- A novel strategy using ionizable lipids and pH-dependent fusion achieved unidirectional enzyme orientation.
- Up to 3-fold increased ATP synthesis rates were observed with natural substrates (NADH, Q8/10) compared to artificial systems.
Conclusions:
- Lipid composition critically influences respiratory enzyme activity and proton motive force in reconstituted systems.
- Ionizable lipids and controlled pH-dependent fusion enable precise enzyme orientation and efficient bioenergetic function.
- This advanced liposome system provides a powerful platform for studying respiratory chain mechanisms with natural substrates.
