Characterization of the interaction domains of Ure2p, a prion-like protein of yeast.

In the yeast Saccharomyces cerevisiae, the non-Mendelian inherited genetic element [URE3] behaves as a prion. A hypothesis has been put forward which states that [URE3] arises spontaneously from its cellular isoform Ure2p (the product of the URE2 gene), and propagates through interactions of the N-terminal domain of the protein, thus leading to its aggregation and loss of function. In the present study, various N- and C-terminal deletion mutants of Ure2p were constructed and their cross-interactions were tested in vitro and in vivo using affinity binding and a two-hybrid analysis. We show that the self-interaction of the protein is mediated by at least two domains, corresponding to the first third of the protein (the so-called prion-forming domain) and the C-terminal catalytic domain.