Ion- and Temperature-Programmable Reconfiguration of Subcompartments in Synthetic Cells

Area of Science:

• Synthetic biology
• Biophysics
• Materials science

Background:

• Spatial reorganization of cellular subcompartments is vital for biological functions.
• Dynamic reconfiguration of synthetic cells is a significant challenge.
• The role of specific ions, particularly magnesium ions (Mg2+), in bottom-up synthetic biology is underexplored.

Purpose of the Study:

• To present a magnesium ion (Mg2+)-mediated mechanism for reversible subcompartment assembly in synthetic cells.
• To investigate Mg2+ as a key regulator of membrane interactions and organization in synthetic systems.

Main Methods:

• Utilized giant unilamellar vesicles (GUVs) as synthetic cell chassis and large unilamellar vesicles (LUVs) as subcompartments.
• Investigated Mg2+-mediated adhesion between oppositely charged GUVs and neutral LUVs.
• Manipulated Mg2+ concentration (using EDTA for chelation) and temperature to control subcompartment assembly and disassembly.

Main Results:

• Demonstrated that Mg2+ mediates stable adhesion between GUVs and LUVs, forming subcompartment layers.
• Showcased reversible control: Mg2+ removal disrupted adhesion, while its reintroduction restored it.
• Identified factors influencing adhesion: membrane charge density, lipid phase state, and temperature.
• Observed temperature-programmed reassembly, with adhesion lost above the LUV phase transition temperature and regained upon cooling.

Conclusions:

• Established a minimal physicochemical framework for dynamic synthetic cell organization using Mg2+ and physical stimuli.
• Highlighted a primitive lipid-ion mechanism for membrane contact phenomena, relevant to early cellular evolution.
• Provided a novel strategy for controlling subcompartment dynamics in synthetic cells through ion concentration and temperature.