Thermostability of model protocell membranes

Area of Science:

• Origin of life studies
• Biochemistry
• Astrobiology

Background:

• The earliest life forms likely originated from self-replicating molecules enclosed within membranes.
• Understanding the properties of primitive membranes is crucial for understanding early cellular evolution.

Purpose of the Study:

• To investigate the thermostability of simple amphiphile-based vesicles.
• To determine if these vesicles can retain genetic material (RNA and DNA) under extreme temperatures.
• To explore the potential role of thermal fluctuations in early cellular processes like replication and nutrient uptake.

Main Methods:

• Vesicles were synthesized using single-chain amphiphiles like fatty acids, fatty alcohols, and fatty-acid glycerol esters.
• Vesicle thermostability and retention of RNA and DNA oligonucleotides were tested across a temperature range of 0°C to 100°C.
• The permeability of fatty-acid membranes to charged molecules like nucleotides at elevated temperatures was assessed.

Main Results:

• Vesicles composed of simple amphiphiles exhibited remarkable thermostability, maintaining integrity from 0°C to 100°C.
• Internal RNA and DNA oligonucleotides were successfully retained within the vesicles across the tested temperature range.
• Strand separation of double-stranded DNA occurred at high temperatures while remaining encapsulated, and nucleotides rapidly crossed membranes at elevated temperatures.

Conclusions:

• Simple amphiphile-based membranes are sufficiently thermostable to encapsulate and protect genetic material during thermal cycling.
• Thermal fluctuations may have played a key role in primitive protocell replication by facilitating DNA strand separation and nutrient uptake.
• These findings support the hypothesis that fatty-acid-based vesicles could have served as early protocells, enabling the transition from non-living matter to life.