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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.

The mechanism of prion inhibition by HET-S., Greenwald J, Buhtz C, Ritter C, Kwiatkowski W, Choe S, Maddelein ML, Ness F, Cescau S, Soragni A, Leitz D, Saupe SJ, Riek R, Mol Cell. 2010 Jun 25;38(6):889-99. PMID:20620958

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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Categories: Podospora anserina | Buhtz, C. | Choe, S. | Greenwald, J. | Kwiatkowski, W. | Riek, R. | Ritter, C. | Saupe, S J. | Heterokaryon incompatibility | Prion regulatory domain | Prion-binding protein