A promiscuous intermediate underlies the evolution of LEAFY DNA binding specificity

LEAFY Evolution It is generally believed that redundancy across gene copies allows for the evolution of novel function in proteins. However, it is less clear how single-copy genes with crucial function may evolve. Sayou et al. (p. 645 , published online 16 January; see the Perspective by Kovach and Lamb ) examined the evolution of the essential plant transcription factor LEAFY, which is generally found as a single-copy gene. LEAFY homologs in taxa representing the major evolutionary branches of the land plants and algae exhibited three classes of LEAFY binding sites. Structural analysis identified amino acid changes in the proteins, that were responsible for contacts with specific DNA motifs and allowed the likely effects of specific amino acid changes over the evolution of land plants to be resolved.