A recent study published in the online Early Edition of the Proceedings of the National Academy of Scientists details how scientists have managed to create a ribozyme that can amplify genetic information and generate functional molecules. Senior author of the study, TSRI Professor Gerald F. Joyce states “This is probably the first time some of these complex RNA molecules have been synthesized with a ribozyme since the end of the RNA world four billion years ago.”
The new ribozyme has the ability to replicate short sections of RNA efficiently and perform transcription on longer RNA’s. This resulted in the creation of functional RNA molecules that have complex structures similar to what scientists predict in terms of an RNA replicator that could have supported life before modern biology was around. Joyce and TSRI Research Associate David P. Horning set out by using the RNA polymerase ribozyme first as is already known to be able to perform RNA synthesis. But, prior forms were limited to the RNA sequences they could handle and were unable to transcribe RNA’s that were of the simplest form. Due to these factors, they couldn’t perform full replication of the RNA.
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So, Joyce and Horning then used previous research to create around 100 trillion different variants of the molecule by adding random mutations to it. By imitating the process of natural selection, they were able to set up a system to isolate only the ribozyme variants that were able to be synthesized. They finally found a winner in the polymerase ribozyme 24-3 that proved successful in both synthesizing the two target-binding RNA’s and other RNA molecules in existence. It was also able to do this about 100 times faster than its predecessor. The other big success for the ribozyme 24-3 was that could copy RNA’s of up to 24 nucleotides and create around 40,000 copies of a target RNA in just one day.
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The team is very happy with the results of the study as have discovered that the 24-3 ribozyme is the first ever to combine RNA synthesis with RNA replication (both of which are necessary for a world of RNA life). But, there are still improvements to be made in enabling the replication of longer RNA molecules and studies are still ongoing at the Joyce laboratory.
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