Departure from randomness: Evolution of self-replicators that can self-sort through steric zipper formation

Area of Science:

• Origin of life studies
• Synthetic biology
• Chemical evolution

Background:

• Darwinian evolution requires self-replicators with accessible structural space, limited occupancy, and navigation via mutation and selection.
• The emergence of life from inanimate matter likely involved Darwinian evolution of self-replicating entities.

Purpose of the Study:

• To investigate a synthetic system exhibiting Darwinian evolution.
• To explore how self-replicating macrocycles adapt to different selection pressures.

Main Methods:

• Formation of self-replicating hexameric macrocycles from two building blocks.
• Analysis of sequence space occupancy and favored sequences (alternating blocks via steric zipper formation).
• Studying replication and destruction dynamics under varying conditions (non-selective vs. selective destruction).

Main Results:

• The system formed self-replicating hexameric macrocycles occupying a subset of possible sequences.
• Steric zipper formation favored alternating block sequences.
• Under non-selective destruction, faster replicators dominated.
• Under selective destruction, a mutant balancing replication speed and resistance to reduction became dominant.

Conclusions:

• The synthetic macrocycle system demonstrates a rudimentary form of Darwinian evolution.
• Replicators can adapt to changing selection pressures through mutation and selection.
• This system provides insights into the fundamental principles of evolution and the origin of life.