Prions of Yeast Are Genes Made of Protein: Amyloids and Enzymes
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Excerpt
In 1994 we described two infectious proteins (prions)of Saccharomyces cerevisiae, showing that the nonchromosomal genes [URE3] and [PSI] are inactive, self-propagating forms of Ure2p and Sup35p, respectively (Wickner 1994). Since then, [Het-s], a prion of Podosporaanserina (Coustou et al. 1997), and [PIN+], another S.cerevisiae prion (Derkatch et al. 1997, 2001; Sondheimerand Lindquist 2000), have been found. All of the aboveprions are based on self-propagating amyloids. Recently,we described another prion, called [β], which is based onthe trans self-activation by the yeast vacuolar protease B(Roberts and Wickner 2003). Evidence has appeared suggesting that C, the non-Mendelian gene of Podosporaanserina determining Crippled Growth, is also a self-activating prion of a MAP kinase kinase kinase (Kicka andSilar 2004). Study of these yeast and fungal phenomenahas established that proteins can be genes and infectiousentities and has revealed many details of what makes aprotein infectious...
