Yeast Prion
Sup35p is a yeast protein involved in recognising stop codons and causing translation to stop correctly at the ends of proteins. Sup35p comes in a normal form and a prion form . When is present, this depletes the amount of normal Sup35p available. As a result, the rate of errors in which translation continues beyond a stop codon increases from about 0.3% to about 1%.
This can lead to different growth rates, and sometimes different morphologies, in matched and strains in a variety of stressful environments. Sometimes the strain grows faster, sometimes : this depends on the genetic background of the strain, suggesting that taps into pre-existing cryptic genetic variation. Mathematical models suggest that may have evolved, as an evolutionary capacitor, to promote evolvability.
appears more frequently in response to environmental stress. In yeast, more stop codon disappearances are in-frame, mimicking the effects of, than would be expected from mutation bias or than are observed in other taxa that do not form the prion. These observations are compatible with acting as an evolutionary capacitor in the wild.
Read more about this topic: Evolutionary Capacitance
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