NR ASWA
AU Baxa,U.; Cheng,N.; Winkler,D.C.; Chiu,T.K.; Davies,D.R.; Sharma,D.; Inouye,H.; Kirschner,D.A.; Wickner,R.B.; Steven,A.C.
TI Filaments of the Ure2p prion protein have a cross-beta core structure
QU Journal of Structural Biology 2005 May; 150(2): 170-9
PT journal article
AB Formation of filaments by the Ure2 protein constitutes the molecular mechanism of the [URE3] prion in yeast. According to the "amyloid backbone" model, the N-terminal asparagine-rich domains of Ure2p polymerize to form an amyloid core fibril that is surrounded by C-terminal domains in their native conformation. Protease resistance and Congo Red binding as well as beta-sheet content detected by spectroscopy-all markers for amyloid-have supported this model, as has the close resemblance between 40 A N-domain fibrils and the fibrillar core of intact Ure2p filaments visualized by cryo-electron microscopy and scanning transmission electron microscopy. Here, we present electron diffraction and X-ray diffraction data from filaments of Ure2p, of N-domains alone, of fragments thereof, and of an N-domain-containing fusion protein that demonstrate in each case the 4.7A reflection that is typical for cross-beta structure and highly indicative of amyloid. This reflection was observed for specimens prepared by air-drying with and without sucrose embedding. To confirm that the corresponding structure is not an artifact of air-drying, the reflection was also demonstrated for specimens preserved in vitreous ice. Local area electron diffraction and X-ray diffraction from partially aligned specimens showed that the 4.7A reflection is meridional and therefore the underlying structure is cross-beta.
MH Microscopy, Electron, Transmission; Polymers; Prions/*chemistry; Protein Conformation; Research Support, Non-U.S. Gov't; Saccharomyces cerevisiae Proteins/*chemistry; X-Ray Diffraction
AD Laboratory of Structural Biology, National Institute of Arthritis, Musculoskeletal, and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
SP englisch
PO USA