The Mechanism of Prion Inhibition by Het-S.
Greenwald, J., Buhtz, C., Ritter, C., Kwiatkowski, W., Choe, S., Maddelein, M.L., Ness, F., Cescau, S., Soragni, A., Leitz, D., Saupe, S.J., Riek, R.(2010) Mol Cell 38: 889
- PubMed: 20620958 
- DOI: https://doi.org/10.1016/j.molcel.2010.05.019
- Primary Citation of Related Structures:  
2WVN, 2WVO, 2WVQ - PubMed Abstract: 
HET-S (97% identical to HET-s) has an N-terminal globular domain that exerts a prion-inhibitory effect in cis on its own prion-forming domain (PFD) and in trans on HET-s prion propagation. We show that HET-S fails to form fibrils in vitro and that it inhibits HET-s PFD fibrillization in trans. In vivo analyses indicate that beta-structuring of the HET-S PFD is required for HET-S activity. The crystal structures of the globular domains of HET-s and HET-S are highly similar, comprising a helical fold, while NMR-based characterizations revealed no differences in the conformations of the PFDs. We conclude that prion inhibition is not encoded by structure but rather in stability and oligomerization properties: when HET-S forms a prion seed or is incorporated into a HET-s fibril via its PFD, the beta-structuring in this domain induces a change in its globular domain, generating a molecular species that is incompetent for fibril growth.
Organizational Affiliation: 
Laboratory of Physical Chemistry, ETH Zürich, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland.