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Protein dispensability and rate of evolution
1enter for Computational Genetics and Biological Modeling, Department of Biological Sciences, Stanford University, California, USA. aehirsch@stanford.edu
Nature
|June 29, 2001
Summary
Protein dispensability, or how essential a protein is to an organism, correlates with its evolutionary rate. This finding, confirmed in yeast and worms, explains previous difficulties in detecting this relationship.
Area of Science:
- Evolutionary biology
- Genomics
- Molecular biology
Background:
- The rate of protein evolution is hypothesized to increase with decreased protein importance to organismal fitness.
- This is because less essential proteins are under weaker purifying selection, allowing faster accumulation of slightly deleterious mutations.
- Previous studies have failed to confirm this relationship, with some showing no difference in evolutionary rates between essential and non-essential genes.
Purpose of the Study:
- To investigate the relationship between protein dispensability and evolutionary rate using a quantitative measure of dispensability.
- To determine if protein dispensability influences evolutionary rate more accurately than a simple essential/non-essential categorization.
- To assess the evolutionary conservation of the relationship between protein dispensability and evolutionary rate.
Main Methods:
- Quantitative assessment of protein dispensability using high-throughput growth assays of single gene deletions in yeast.
- Estimation of evolutionary rates through comparative sequence analysis of 21 fully annotated genomes.
- Statistical analysis to correlate protein dispensability with evolutionary rates.
Main Results:
- A highly significant positive correlation was found between protein dispensability and evolutionary rate.
- The relationship is more nuanced than a simple essential versus non-essential dichotomy, explaining previous failed attempts at confirmation.
- The identified relationship between protein dispensability and evolutionary rate in yeast is conserved and predictive in other species, such as the nematode worm.
Conclusions:
- Protein dispensability is a significant predictor of evolutionary rate.
- Quantitative measures of dispensability reveal a conserved relationship between protein function importance and evolutionary speed.
- This study reconciles previous conflicting findings and provides a more accurate model for understanding protein evolution.
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