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Department Seminar: Exploring the evolutionary innovations of RNA molecules from a synthetic biology perspective
June 22, 2018 @ 1:00 pm - 2:00 pm
Exploring the evolutionary innovations of RNA molecules from a synthetic biology perspective
Dr. Eric Hayden
Department of Biological Sciences
Boise State University
Friday, June 22, 2018
Natural Sciences I, Room 1114
1:00 PM – 2:00 PM
The mechanisms by which evolution produces new structures and functions has intrigued biologists since the earliest formulations of evolutionary theory. In this context, a useful concept is the genotype network, defined as all the genotypes that produce the same phenotype3. It has been proposed that evolutionary innovations can occur where two genotype networks are in close proximity. RNA molecules have been an important model system for understanding genotype networks because each RNA molecule has both a genotype (nucleotide sequence) and a phenotype (structure or function). Computational predictions of RNA structures have shown that genotype networks of different structures can be intertwined, providing numerous points where two folds are in close proximity. In some cases, genotype networks may even intersect at genotypes that can produce two different phenotypes. Such intersections could promote evolutionary innovations by providing new functions prior to gene duplication and genetic divergence. However, only isolated examples of intersection sequences have been demonstrated. Here we show that the genotype networks of two different RNA enzymes overlap extensively through numerous intersection genotypes. We applied two different high-throughput RNA assays to the same RNA sequences and found that over half of the 16,384 mutational neighbors studied can perform both functions to some extent. From our quantitative phenotype measurements we conducted data-driven evolutionary simulations, which show that the rate of adaptation depends upon the specific starting locations in the genotype networks. The extensive overlap in our experimental networks suggest that functional divergence is likely to precede gene duplication in the evolution of RNA innovations, and that many new functional intersections are awaiting discovery.