Before the emergence of DNA on Earth some four billion years ago, some scientists theorize that our planet was an “RNA World.” The idea gained traction in the 1980s, when scientists discovered that RNA held catalytic properties—evidence that it could store genetic information and catalyze chemical reactions on its own, before DNA or even basic proteins existed.
“Many doubts have been raised about whether or not the original genetic/catalytic material could have been RNA as we know it today because extreme conditions on the primitive Earth might have led to the rapid chemical degradation of RNA,” wrote Yale chemist and Nobel laureate Sidney Altman, who discovered RNA’s catalytic properties. “Nevertheless, even if the precise chemical nature of the early genetic/catalytic material differed from present-day RNA, it seems reasonable to conclude that the RNA World did exist at some time.”
If human ingenuity one day devises a time machine, any temporal explorer would be wise to avoid Earth during the Hadean Eon. The planet’s incredibly fast spin meant days were only six hours long, landscapes bubbled from molten activity, and the surface was regularly bombarded by leftover material from our star’s protoplanetary disk. One collision was so large that it created the Moon. This less-than-cozy setting is one reason some scientists doubt that fragile RNA could survive such heat and acidity, let alone interact enough to form the foundation of life as we know it.
Now, researchers at the University at Buffalo (UB) and Princeton University have taken a closer look at this head-scratching question and found that one key chemical difference between RNA and DNA might explain its unexpected survival. In research published in the journal Nature Communications, UB professor and lead author Priya Banerjee and his team specifically analyzed the chemical group 2′-hydroxyl (2′-OH), which is absent in DNA, using temperature-controlled microscopy, small-angle x-ray scattering, and molecular-dynamics simulations. What the researchers found is that this group essentially nudges the RNA to interact more readily as temperatures rise, forming gel-like droplets that, on the early Earth, could have sheltered the molecule long before cell walls evolved.
“These findings reveal, for the first time, how remarkably small changes in molecular chemistry can control the emergence of much larger, self-organized biomolecular structures like RNA condensates,” Banerjee said in a press statement. “They could allow us to eventually address even deeper questions, like whether these condensates helped bridge the gap between simple molecules and the earliest forms of life.”
This work builds on a 2023 Nature Chemistry study in which Banerjee and his colleagues first showed that these RNA droplets form at high temperatures. Having pinned down the key ingredient behind this nifty bit of chemical self-preservation, Banerjee and his team are now testing whether the droplets behave in cell-like ways. That work, he says, could help uncover an important piece of life's early story on Earth. “These kinds of self-organizing RNA compartments were possibly a step along the way to single-cell organisms,” he said.
Darren lives in Portland, has a cat, and writes/edits about sci-fi and how our world works. You can find his previous stuff at Gizmodo and Paste if you look hard enough.