Metabolism, not RNA, jump-started life's molecular beginnings

By Brooks Hays  |  May 17, 2017 at 2:41 PM
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May 17 (UPI) -- How did organic molecules come to birth life?

Some scientists have hypothesized that ribonucleic acid molecules, or RNA, jump-started life. But others say RNA is too big and complex to have come first. Instead, "metabolism-first" proponents argue simple carbon-based molecules first evolved metabolic functions.

New research published in the journal PLOS ONE lends support to the metabolism-first hypothesis.

Researchers traced the evolution of metabolism using the Gene Ontology database, which features a catalogue of biological functions and their corresponding protein or RNA molecule found in the genomes of 249 organisms.

"You can take an entire genome that represents an organism, like the human genome, and visualize it through the collection of functionalities of its genes," Gustavo Caetano-Anollés, a bioinformatician at the University of Illinois, said in a news release. "The study of these 'functionomes' tells us what genes do, instead of focusing on their names and locations."

The most ancient genetic functions appear in genomes more frequently than functions that evolved more recently.

Researchers built a computational model to analyze the Gene Ontology database and produce an evolutionary tree of genetic functions. The study authors found the most ancient genetic functions, found at the roots of the evolutionary tree, were related to metabolism and binding.

"It is logical that these two functions started very early because molecules first needed to generate energy through metabolism and had to interact with other molecules through binding," Caetano-Anollés said.

The genetic functions that made the production of macromolecules like RNA possible were found farther up the trunk.

Researchers say their unique analytical method and model could be used to bioengineer molecules for medical treatments, or to predict the genetic adaptations of tomorrow.

"People think of evolution as looking backwards," Caetano-Anollés said. "But we could use our chronologies and methodologies to ask what novel molecular functions will be generated in the future."

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