Self-Making Ribozyme Pairs Get Competitive

Inspired by the notion that RNA might have been the original chemical machinery of life, researchers have generated an RNA-based system that can replicate itself in a test tube (Science, DOI: 10.1126/science.1167856). The system consists of two RNA enzymes, or ribozymes, that build each other by joining two oligonucleotide building blocks. Previous incarnations of this synthetic system weren't efficient because the enzymes were too slow and the building blocks associated too tightly with each other to allow many rounds of replication. To overcome these limitations, Scripps Research Institute's Tracey A. Lincoln and Gerald F. Joyce used an in vitro evolution screening process to identify a pair of ribozymes that can replicate indefinitely—as long as they're supplied with building blocks. To illustrate their ribozymes' potential as a model genetic system, Lincoln and Joyce made 12 variations of the original pair and allowed them to compete for a common pool of building blocks. Hybrid pairings eventually emerged, and a few of these pairings came to dominate the population, resembling processes that may have occurred when life first evolved.