Researchers seeking to understand how life may have emerged from Earth’s primordial soup have found an interesting behavior of ribonucleic acid (RNA), which they suggest could have given way to RNA-based life.
The team’s research, published this week in the Proceedings of the National Academy of Sciences, describes a ribozyme that could create an environment in which RNA replicates itself more accurately. Other efforts at self-replicating RNA had resulted in new versions with far too many errors to remain functional.
“We’re chasing the dawn of evolution,” says Gerald Joyce, a co-author of the paper and president of the Salk Institute, in an institute release. “By revealing these novel capabilities of RNA, we’re uncovering the potential origins of life itself, and how simple molecules could have paved the way for the complexity and diversity of life we see today.”
The RNA World hypothesis is the idea that RNA could have jumpstarted Earth’s biology without DNA or proteins. The hypothesis relies on ribozymes, RNA molecules that do the functions of enzymes, which are proteins that catalyze and accelerate chemical reactions.
In their lab experiment, the researchers developed a particular RNA polymerase ribozyme that is able to produce RNA strands with greater accuracy than previous efforts. Those previous efforts yielded ribozymes that were able to produce new versions of themselves, but eventually so many errors were added to the strands that the ribozymes lost their functionality.
The ribozymes the team worked with were “hammerheads,” a kind that splits other RNA molecules. New variants of the ribozyme hammerhead produced in the process were easier to replicate than the original hammerheads the team used. The hammerheads from the higher-fidelity polymerase (depicted at right in the video above) retained their functions and produced new sequences, while the hammerheads yielded by the lower-fidelity polymerase lost their function (depicted as a white dot in the above plots).
“This study suggests the dawn of evolution could have been very early and very simple,” said Nikolaos Papastavrou, a researcher at the Salk Institute and the study’s lead author, in the release. “Something at the level of individual molecules could sustain Darwinian evolution, and that might have been the spark that allowed life to become more complex, going from molecules to cells to multicellular organisms.”
The team has not yet produced a self-replicating RNA polymerase; that is to say, a ribozyme for which this replication process is self-sustaining. According to the researchers, that autonomous RNA operation could happen in the next decade.