Scientists create tiny RNA molecule with big implications for life's origins

An extremely small RNA molecule created by a University of Colorado at Boulder team can catalyze a key reaction needed to synthesize proteins, the building blocks of life. The findings could be a substantial step toward understanding "the very origin of Earthly life," the lead researcher contends.

The smallest RNA enzyme ever known to perform a cellular chemical reaction is described in a paper published this week in the Proceedings of the National Academy of Sciences. The paper was written by CU graduate student Rebecca Turk, research associate Nataliya Chumachenko and Professor Michael Yarus of the molecular, cellular and developmental biology department.

Cellular RNA can have hundreds or thousands of its basic structural units, called nucleotides. Yarus' team focused on a ribozyme -- a form of RNA that can catalyze chemical reactions -- with only five nucleotides.

Tom Blumenthal, a professor and chair of the MCDB department, noted that Tom Cech, a Nobel laureate and distinguished professor of chemistry and biochemistry at CU, and Professor Norman Pace of MCDB, independently discovered that RNA can act as an enzyme, carrying out chemical reactions. That "pioneering work" has been carried on further by Yarus, Blumenthal said.

Because proteins are complex, one vexing question is where the first proteins came from, Blumenthal said. "It now appears that the first catalytic macromolecules could have been RNA molecules, since they are somewhat simpler, were likely to exist early in the formation of the first life forms, and are capable of catalyzing chemical reactions without proteins being present," he said.

"In this paper the Yarus group has made the amazing discovery that even an extremely tiny RNA can by itself catalyze a key reaction that would be needed to synthesize proteins," Blumenthal said. "Nobody expected an RNA molecule this small and simple to be able to do such a complicated thing as that."

The finding adds weight to the "RNA World" hypothesis, which proposes that life on Earth evolved from early forms of RNA. "Mike Yarus has been one of the strongest proponents of this idea, and his lab has provided some of the strongest evidence for it over the past two decades," Blumenthal said. ...

via U. of Colorado scientists create tiny RNA molecule with big implications for life's origins.