How was membrane permeability produced in an RNA world?

Area of Science:

• Origin of Life Studies
• Biochemistry
• Molecular Evolution

Background:

• Darwinian evolution in an RNA World necessitated compartmentalization within membranes.
• Cellular membranes pose challenges for nutrient uptake and waste excretion due to impermeability.
• RNA molecules interact with lipid membranes, with potential for specific binding via SELEX.

Purpose of the Study:

• To explore RNA-based mechanisms for membrane permeability in early cellular evolution.
• To investigate the role of RNA in nutrient transport and waste excretion.
• To understand the evolutionary pressure for protein development in membrane function.

Main Methods:

• Review of existing hypotheses on RNA-membrane interactions.
• Consideration of SELEX (Systematic Evolution of Ligands by Exponential Enrichment) for generating binding species.
• Theoretical analysis of supramolecular RNA complexes and their potential membrane interactions.

Main Results:

• No natural or selected RNA channels or transmembrane shuttles are currently known.
• RNA can form weak, non-specific interactions with lipid membranes.
• Supramolecular RNA complexes are hypothesized to transiently open membranes.

Conclusions:

• RNA-based transport mechanisms are crucial for early cellular life but remain largely undiscovered.
• The need for selective membrane permeability likely drove the evolution of proteins.
• Proteins may have been essential for creating hydrophobic structures enabling controlled transport across membranes.