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Rewiring the keyboard: evolvability of the genetic code.
R D Knight1, S J Freeland, L F Landweber
1Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA. rdknight@princeton.edu
Nature Reviews. Genetics
|March 17, 2001
Summary
The genetic code evolved, with secondary deviations arising mainly from changes in transfer RNA (tRNA). These alterations often occur through post-transcriptional modifications rather than anticodon substitutions.
Area of Science:
- Evolutionary biology
- Genetics
- Molecular biology
Background:
- The canonical genetic code predates the last universal ancestor.
- Subsequent divergence occurred in nuclear and organelle lineages.
- Understanding secondary deviations is crucial for evolutionary insights.
Purpose of the Study:
- To investigate the distribution and causes of secondary deviations from the canonical genetic code.
- To identify the primary mechanisms driving these genetic code variations.
Main Methods:
- Analysis of genetic code variations across different lineages.
- Examination of transfer RNA (tRNA) alterations.
- Distinguishing between tRNA anticodon substitutions and post-transcriptional modifications.
Main Results:
- The majority of non-standard genetic codes originate from alterations in tRNA.
- Most tRNA alterations involve post-transcriptional modifications like base modification or RNA editing.
- Substitutions within tRNA anticodons are a less common cause of deviation.
Conclusions:
- Secondary deviations in the genetic code are predominantly driven by tRNA modifications.
- Post-transcriptional modifications represent a key evolutionary mechanism for genetic code plasticity.
- The study clarifies the molecular basis of genetic code evolution beyond the canonical system.