We have been focusing our approach on studying how alterations in primary structure of prion proteins can affect chaperone interactions. We have been isolating mutants of prion proteins that fall into two major classes, those that interfere with propagation of prions formed of wild type proteins and those that don't. Both types of mutants contain subclasses that, in the absence of wild type protein, either form prions with weakened phenotypes or are unable to form prions. We are using genetic and biochemical methods to determine if the observed effects on prion phenotpye are due to differences in how the prion proteins self-associate or interact with various chaperones. We are also isolating mutations in the Ure2 pion protein (the prion determinant of the URE3 prion) to identify alterations that specifically interfere with the ability of the Hsp40 chaperone Ydj1 to cure cells of URE3. Our preliminary work suggests that the prion protein mutations can influence propagation of amyloid or the interaction of chaperones that in turn affect how efficiently the prions propagate.
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