In Sup35p filaments (the [PSI+] prion), the globular C-terminal domains are widely offset from the amyloid fibril backbone.

ABSTRACT: In yeast cells infected with the [PSI+] prion, Sup35p forms aggregates and its activity in translation termination is downregulated. Transfection experiments have shown that Sup35p filaments assembled in vitro are infectious, suggesting that they reproduce or closely resemble the prion. We have used several EM techniques to study the molecular architecture of filaments, seeking clues as to the mechanism of downregulation. Sup35p has an N-terminal 'prion' domain; a highly charged middle (M-)domain; and a C-terminal domain with the translation termination activity. By negative staining, cryo-EM and scanning transmission EM (STEM), filaments of full-length Sup35p show a thin backbone fibril surrounded by a diffuse 65-nm-wide cloud of globular C-domains. In diameter (∼8 nm) and appearance, the

SUBMITTER: Baxa U 

PROVIDER: S-EPMC3079393 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature