Scientists to Recreate the Primordial "RNA World" of 4 Billion Years Ago

Scientists from The Scripps Research Institute takes a one step closer in recreating the RNA World of four billion years ago as they successfully created an enzyme capable of both amplifying genetic information and generating functional molecules.

"This is probably the first time some of these complex RNA molecules have been synthesized with a ribozyme [a special RNA enzyme] since the end of the RNA world four billion years ago," said Gerald F. Joyce, a professor at TSRI and senior author of the study, in a statement.

RNA World refers to the self-replicating ribonucleic acid (RNA) molecules that are generally believed to have preceded modern life forms based on deoxyribonucleic acid (DNA) and proteins.

The newly synthesized ribozyme, described in the paper published in the journal Proceedings of the National Academy of Science, is capable of replicating short lengths of RNA efficiently and perform transcription on even longer RNAs to make functional RNA molecules with complex structure.

In order to synthesize a rybozyme capable of supporting the RNA World, the researchers created a population of roughly 100 trillion distinct variants of class I RNA polymerase ribozyme. The class I RNA polymerase ribozyme is an enzyme developed and improved upon by other scientists since the early 1990s.

From the trillions of variants, the researchers selected ribozymes capable of producing two different and challenging RNA molecules. These RNA molecules should have mixed sequences and complex structures, with the ability to bind tightly to specific target molecules.

After two dozen rounds of selection, the best performer, polymerase ribozyme 24-3, proved to be capable of synthesizing not only wo target-binding RNAs but also several other structurally complex RNA molecules that exist in nature.

Polymerase ribozyme 24-3 also have the ability to stitch together RNA sequences about 100 times faster than the class I RNA polymerase ribozyme. Furthermore, the newly synthesized ribozyme could also copy RNAs of up to two dozen nucleotides, achieving what biologists call "exponential replication" and creating as many as 40,000 copies of a target RNA within 24 hours.

With their findings, the researchers are now searching for ways to improve the new ribozyme to replicate longer, more complex RNA molecules in order to generate and sustain true RNA World.