I understand that prions have been implicated in the passing on of epigentic information[1]. Are prions thought to play a significant role in the evolution of organisms?

  1. Alberti S, Halfmann R, King O, Kapila A, Lindquist S. 2009. A systematic survey identifies prions and illuminates sequence features of prionogenic proteins. Cell 137: 146–58.
  • $\begingroup$ @aland Thanks for your effort to improve the quality of citations in the questions and answers on this site. You may be interested in this thread in the meta regarding the best location for complete/verbose references. $\endgroup$ Sep 14, 2012 at 19:51

1 Answer 1


It is proposed that prions are a good mechanism for "testing" phenotypic variation.

There are many identified proteins with prion-determining domains (PrD) in the yeast genome that can spontaneously switch between conformations with some low probability (eg: check SUP35 for one example, and [1] for a good overview of more). The theory is that:

  1. the low probability of switching from non-prion to prion state allows for many more mutations and variations to accumulate -- generating greater genetic diversity than in standard expressed gene variability where most mutations are silent or detrimental
  2. the prions provide a ready form of non-permanent inheritability that can be "trialed" by offspring and others in a colony of organisms -- this can be especially beneficial during say temporary changes in environment
  3. if the prion phenotype is widely successful, selective pressure can easily mutate it into a more permanent fixture in the genome.

Check out the excellent paper published just last week in Nature exploring this this topic [2]. To give a sense of just how evolutionarily-advantageous prions can be, in the author's experiments and analysis they note that 40% of the prion traits they analyzed were beneficial to growth (eg: in the paper strain UCD939 gains additional resistance to acidic conditions from the prion [PSI+]).

Assuming these hypothesis, prions would thus play a significant role in the evolution and variability of organisms.

[1] Crow, et. al. 2011. doi:10.1016/j.semcdb.2011.03.003

[2] Halfmann, et. al. 2012. doi:10.1038/nature10875


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