Mellitic Acid as a Stable Abiotic Precursor for Liquid-Liquid Phase Separation: An RNA-Independent Pathway for...

Area of Science:

• Origin of life studies
• Prebiotic chemistry
• Biophysics

Background:

• Liquid-liquid phase separation (LLPS) is crucial for intracellular organization.
• Prebiotic compartmentalization via LLPS faces challenges due to limited early Earth biopolymers like RNA.
• Abiotic molecules are key to understanding early life formation.

Purpose of the Study:

• To investigate the potential of abiotic molecules for prebiotic compartmentalization.
• To explore mellitic acid (MAc) and poly-L-lysine (PLL) in forming liquid droplets.
• To assess the MAc-PLL system's properties and suitability for early protocells.

Main Methods:

• Formation of MAc-PLL liquid droplets across various pH and mixing ratios.
• Investigated PLL chain-length requirements for LLPS with MAc and ATP.
• Analyzed droplet dynamics, reversibility, and response to ATP using physical parameters.
• Utilized isothermal titration calorimetry (ITC) to study interaction forces.

Main Results:

• MAc and PLL form dynamic liquid droplets over a wide range of conditions.
• MAc requires shorter PLL chain lengths for LLPS compared to ATP.
• MAc-PLL droplets exhibit reversible mixing and demixing with ATP.
• Coulombic interactions are identified as the primary force maintaining droplet stability.

Conclusions:

• MAc-PLL system demonstrates a viable abiotic mechanism for prebiotic membraneless compartments.
• MAc's ability to induce LLPS with short oligocations supports its role in early protocells.
• Abiotic synthesis routes and LLPS capacity position MAc as a key prebiotic ingredient.