Poliovirus 2Apro expression inhibits growth of yeast cells

Poliovirus encodes two proteases, 2Apro and 3Cpro that participate in the processing of the viral polyprotein and cleave a number of host proteins. Both proteases have been cloned and expressed in an inducible manner in Saccharomyces cerevisiae cells. The expression of 2Apro, but not 3Cpro, was highly toxic for yeast cells such that growth was arrested after 5 h of induction and cell survival sharply declined. Cellular morphology was profoundly modified by expression of poliovirus 2Apro, in such a way that electron dense granules and autophagosomic bodies arise in the cytoplasm. Experiments aimed at defining the yeast function affected by 2Apro suggested that translation was not the target of protease toxicity, but showed that RNA synthesis was profoundly blocked.