Dynamics of DNA-protein interaction deduced from in vitro DNA evolution

We report the first experimental study of the dynamics of in vitro, evoluti on of DNA. Starting from a random pool of DNA sequences, we used cycles of selection (binding to the lac repressor protein), amplification, and mutati ons to evolve to a unique DNA sequence, the lac operator. Statistical analy sis of the DNA sequences obtained during the cycles of evolution shows that the DNA bases are selected at different rates. The rates of selection prov ide a quantitative measure of the interaction of the DNA bases with the pro tein during the complex formation. A model reproduces the evolution dynamic s of the DNA population but cannot give the fine structure of the DNA-prote in interaction.