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Scientists have found new evidence that the earliest RNA molecules may have been able to repair themselves before complex proteins evolved, offering fresh insight into one of the key steps in the origin of life on Earth, according to a study published in Nature Communications.
The findings support the long-standing RNA world hypothesis, which proposes that RNA was the first molecule capable of both storing genetic information and catalyzing chemical reactions before DNA and proteins became dominant.
Researchers used laboratory-directed evolution to search for RNA molecules capable of joining fragments together. Instead, they discovered a ribozyme that efficiently repairs breaks in RNA strands.
The repair process works by recognizing a phosphate group that forms at the site of damage, binding to a specific nucleotide sequence, and using magnesium ions to accelerate the repair reaction by up to 100,000 times. The repaired strand forms an unusual 2'-5' chemical bond, which is rare in modern organisms but was found not to impair the RNA molecule's function.
Scientists say the discovery strengthens the idea that early RNA molecules were capable of maintaining themselves without the help of proteins, acting simultaneously as genetic material, catalysts, and repair systems in the earliest stages of life.
Beyond its implications for understanding evolution, the newly identified ribozyme could have medical applications. Researchers believe its ability to recognize specific damaged RNA sequences could eventually help develop highly precise diagnostic tools and RNA-based therapies for viral diseases and certain cancers.
The study also adds to growing evidence that the building blocks of life may have originated before Earth formed, with components of RNA and DNA previously detected in samples returned from the asteroids Ryugu and Bennu.
