Take a step closer to understanding how life on earth began

rnA

Credit: Pixabay / CC0 Public Domain

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

Researchers in SFU molecular biology and professor of biochemistry, Professor Peter Unrau, are working on advancing 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 carry not only genetic information but also chemical reactions that are essential for life, prior to the evolution of deoxyribonucleic acid (DNA). ) and proteins, which now perform both functions within our cells.

Through a process of in vitro evolution in the laboratory, the team isolated a promoter-based RNA polymerase ribosome – an enzyme that can synthesize RNA using RNA as a template, which has process clamping capabilities which is equivalent to the contemporary protein polymerases.

“This RNA polymerase has many of the characteristics of modern protein polymerases; it was developed to recognize an RNA promoter and then to copy RNA processively,” says Unrau. “What our finding implies is that similar RNA enzymes could also reveal such sophisticated biological features early in the evolution of life.”







At the beginning of life, polymerases made from RNA probably replicated RNA genomes and maintained metabolic RNA enzymes that are essential for life. The clamped RNA polymerase ribosome uses a specific primer to recognize an RNA promoter. Once localized, the polymerase rearranges into a processive complex that can copy extended regions of the pattern. This promoter recognition and processivity is similar to many aspects of modern promoter-dependent transcription and shows how early in evolution RNA genes could be replicated and expressed. Credit: Simon Fraser University

There is evidence to suggest that RNA preceded DNA and proteins. The ribosome, the ‘machine’ that produces proteins in our cells, for example, is made up of RNA. Yet proteins are better at catalyzing reactions.

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

DNA is also made from RNA. Since RNA is a practice and can perform the functions of proteins as well as DNA, this suggests that DNA and proteins later evolved as an ‘upgrade’ to improve cellular functions originally supported by RNA.

The clamping polymerase ribosome discovered by Unrau’s laboratory, within SFU’s Burnaby campus, suggests that RNA replication by RNA catalysts would indeed have been possible in such a primitive life.

Unrau and his team’s long-term goal is to build a self-developing system in the laboratory. It involves the creation of an RNA polymerase ribosome that can also replicate and sustain itself, in order to gain a deeper understanding of how early RNA-based organisms originated.







At the beginning of life, polymerases made from RNA probably replicated RNA genomes and maintained metabolic RNA enzymes that are essential for life. The clamped RNA polymerase ribozyme uses a specific primer to recognize an RNA promoter. Once localized, the polymerase rearranges into a process complex that can copy extensive regions of the template. This promoter recognition and processivity is similar to many aspects of modern promoter-dependent transcription and shows how early in evolution RNA genes could be replicated and expressed. Credit: Simon Fraser University

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

“By understanding the fundamental complexity of life in the laboratory, we can begin to estimate the chances of life on other planets and determine the probability that planets like Mars have the potential to house life.


Scientists take a big step towards recreating the original ‘RNA world’ of 4 billion years ago


More information:
Razvan Cojocaru et al, Processive RNA polymerization and promoter recognition in an RNA world, Science (2021). DOI: 10.1126 / science.abd9191

Provided by Simon Fraser University

Quotation: Lab a step closer to understanding how life on earth began (2021, March 19), retrieved on March 19, 2021 from https://phys.org/news/2021-03-lab-closer-life- earth.html

This document is subject to copyright. Except for any fair trade for the purpose of private study or research, no portion may be reproduced without the written permission. The content is provided for informational purposes only.

Source