Evolution in an RNA world

Cold Spring Harb Symp Quant Biol. 2009:74:17-23. doi: 10.1101/sqb.2009.74.004. Epub 2009 Aug 10.

Abstract

A long-standing research goal has been to develop a self-sustained chemical system that is capable of undergoing Darwinian evolution. The notion of primitive RNA-based life suggests that this goal might be achieved by constructing an RNA enzyme that catalyzes the replication of RNA molecules, including the RNA enzyme itself. This reaction was demonstrated recently in a cross-catalytic system involving two RNA enzymes that catalyze each other's synthesis from a total of four component substrates. The cross-replicating RNA enzymes undergo self-sustained exponential amplification at a constant temperature in the absence of proteins or other biological materials. Amplification occurs with a doubling time of approximately 1 hour and can be continued indefinitely. Small populations of cross-replicating RNA enzymes can be made to compete for limited resources within a common environment. The molecules reproduce with high fidelity but occasionally give rise to recombinants that also can replicate. Over the course of many "generations" of selective amplification, novel variants arise and grow to dominate the population based on their relative fitness under the chosen reaction conditions. This is the first example, outside of biology, of evolutionary adaptation in a molecular genetic system.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Base Sequence
  • Directed Molecular Evolution
  • Evolution, Molecular*
  • Models, Genetic
  • Nucleic Acid Conformation
  • Polynucleotide Ligases / chemistry
  • Polynucleotide Ligases / genetics
  • Polynucleotide Ligases / metabolism
  • RNA / chemistry
  • RNA / genetics*
  • RNA / metabolism*
  • RNA, Catalytic / chemistry
  • RNA, Catalytic / genetics
  • RNA, Catalytic / metabolism

Substances

  • RNA, Catalytic
  • RNA
  • Polynucleotide Ligases
  • R3C ligase