Lab one step closer to understanding how life on Earth began

How did life on Earth begin and could it exist elsewhere? Researchers at Simon Fraser University have found a genetic clue – an enzyme known as RNA polymerase – that provides new insights into the origins of life. The research is published in the journal today Science

Researchers in the SFU Molecular Biology and Biochemistry Laboratory, Professor Peter Unrau, are working to advance the RNA world hypothesis in response to fundamental questions about the beginning of life.

The hypothesis suggests that life on our planet began with self-replicating ribonucleic acid (RNA) molecules, which can not only contain genetic information but also direct chemical reactions essential to life, prior to the evolution of deoxyribonucleic acid (DNA) and proteins. they now perform both functions within our cells.

Through a process of in vitro evolution in the laboratory, the team has isolated a promoter-based RNA polymerase ribozyme – an enzyme capable of synthesizing RNA using RNA as a template – that has process clamping capabilities equivalent to modern protein polymerases.

“This RNA polymerase has many of the features of modern protein polymerases; it is designed to recognize an RNA promoter and then processively copy RNA,” says Unrau. “What our finding implies is that similar RNA enzymes early in life’s evolution could also have manifested such advanced biological features.”

There is some evidence that RNA came before DNA and proteins. The ribosome, the ‘machine’ that makes proteins in our cells, is made up of RNA. Still, proteins are better at catalyzing reactions.

This has led experts to theorize that this machine was an invention of the late RNA world that was never discarded by evolution.

DNA is also made from RNA. Since RNA is an all-rounder and can perform the functions of both protein and DNA, this suggests that DNA and proteins later evolved as an “upgrade” to enhance cellular functions originally supported by RNA.

The clamping polymerase ribozyme discovered by Unrau’s lab, located on SFU’s Burnaby campus, indicates that RNA replication by RNA catalysts would indeed have been possible in such a primitive life.

The long-term goal of Unrau and his team is to build a self-evolving system in the laboratory. This would involve creating an RNA polymerase ribozyme that can also replicate and sustain itself, to gain a better understanding of how early RNA-based organisms came into being.

“If we were able to create a living and evolving RNA-based system in the lab, we would have created something very remarkable, something that probably never existed since the beginning of life on this planet”, says Unrau, who published the Scientific article with SFU Ph.D. student Razvan Cojocaru.

“By understanding the fundamental complexities of life, we can start in the lab to estimate the probabilities of life on other planets and determine the likelihood that planets like Mars had or still have the potential to harbor life.”