Protein-Rich Rafts in Hybrid Polymer/Lipid Giant Unilamellar Vesicles

Area of Science:

• Biophysics
• Synthetic Biology
• Membrane Protein Biochemistry

Background:

• Lipid rafts are crucial for cell functions like signaling and trafficking.
• Artificial vesicles aid in understanding lipid phase separation and protein interactions.
• Integrating complex membrane proteins into synthetic systems is challenging.

Purpose of the Study:

• To develop a method for co-reconstituting proton pump (bo3 oxidase) and proton consumer (ATP synthase) into hybrid polymer/lipid giant unilamellar vesicles (GUVs).
• To explore tailored reconstitution protocols for controlling vesicle size and protein function.
• To investigate protein labeling as a synthetic mechanism for phase separation and domain formation.

Main Methods:

• Co-reconstitution of bo3 oxidase and ATP synthase into hybrid polymer/lipid GUVs using fusion/electroformation.
• Variations in vesicle preparation, including mixing protein-free and protein-functionalized nanovesicles.
• Protein labeling to induce synthetic phase separation.

Main Results:

• Successful co-reconstitution of proton pump and consumer in hybrid GUVs.
• Method allows for control over GUV size and tailored reconstitution.
• Separate reconstitution of enzymes led to higher ATP synthesis rates.
• Protein labeling enabled synthetic phase separation, mimicking natural domain formation.

Conclusions:

• The developed method provides a versatile platform for studying membrane protein function in synthetic systems.
• This approach facilitates the bottom-up design of cellular mimics with controlled protein organization.
• Protein-mediated phase separation in synthetic vesicles opens avenues for studying complex biological phenomena like supercomplex assembly.