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Directed Evolution Method in Saccharomyces cerevisiae: Mutant Library Creation and Screening
Published on: April 1, 2016
In vitro evolution suggests multiple origins for the hammerhead ribozyme.
K Salehi-Ashtiani1, J W Szostak
1Howard Hughes Medical Institute and Department of Molecular Biology, Massachusetts General Hospital, Boston 02114, USA.
Nature
|November 2, 2001
Summary
The hammerhead ribozyme, a self-cleaving RNA motif, is the simplest and most common structure for RNA self-cleavage under physiological conditions. This suggests evolution favors the simplest solution for biochemical problems, explaining its widespread occurrence.
Area of Science:
- Molecular Biology
- Evolutionary Biology
- Biochemistry
Background:
- The hammerhead ribozyme is a self-cleaving RNA motif found in diverse organisms, including plants, newts, schistosomes, and cave crickets.
- Its sporadic distribution suggests either ancient origins or independent evolution across different species.
- Understanding the evolutionary pressures shaping ribozyme distribution is crucial.
Purpose of the Study:
- To investigate the evolutionary origins and distribution of the hammerhead ribozyme.
- To determine the simplest RNA structure capable of self-cleavage at biologically relevant rates.
- To explore whether evolutionary processes favor simpler solutions for biochemical functions.
Main Methods:
- In vitro selection was employed to screen an unbiased library of random RNA sequences.
- The selection aimed to identify self-cleaving motifs with activity comparable to known hammerhead ribozymes.
- Experiments were conducted under near-physiological conditions to mimic biological environments.
Main Results:
- The hammerhead ribozyme motif emerged as the most common and simplest RNA structure capable of self-cleavage.
- This self-cleavage occurred at rates comparable to those observed in biological systems.
- The findings were consistent across near-physiological conditions.
Conclusions:
- The hammerhead ribozyme's prevalence suggests that evolutionary pathways are often channeled towards the simplest biochemical solutions.
- This principle of selecting the simplest functional structure may explain its widespread occurrence in nature.
- Laboratory selection mirrors natural evolutionary processes in favoring simplicity.
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