NR AUAD
AU Fayard,B.; Fay,N.; David,G.; Doucet,J.; Melki,R.
TI Packing of the prion Ure2p in protein fibrils probed by fluorescence X-ray near-edge structure spectroscopy at sulfur K-edge
QU Journal of Molecular Biology 2006 Mar 3; 356(4): 843-9
PT journal article
AB The soluble protein Ure2p from the yeast Saccharomyces cerevisiae assembles in vitro into straight and insoluble protein fibrils, through subtle changes of conformation. Whereas the structure of soluble Ure2p has been revealed by X-ray crystallography, further characterization of the structure of insoluble Ure2p fibrils is needed. We performed X-ray absorption near-edge spectroscopy (XANES) at the sulfur K-edge to probe the state of Cys221 in the fibrillar form of Ure2pC221 and provide structural information on the structure of Ure2p within fibrils. Although the Ure2p dimer dissociation into its constituent monomers has proven to be a prerequisite for assembly into fibrils, we showed the ability of every Ure2pC221 monomer to establish disulfide bonds upon incubation of the fibrils under oxidizing conditions. Our result indicates either that the constituent unit of the fibrillar form of the protein is a dimeric Ure2p or that the fibrils are made of protofilaments assembled in such a way that the residue C221 from a Ure2p molecule in one protofilament is located in the vicinity of a C221 residue from another molecule belonging to a neighbor protofilament.
MH Disulfides/chemistry; Oxidation-Reduction; Prions/*chemistry/genetics; *Protein Conformation; Research Support, Non-U.S. Gov't; Saccharomyces cerevisiae/chemistry; Saccharomyces cerevisiae Proteins/*chemistry/genetics; Spectrum Analysis/methods; Sulfur/*chemistry
AD Laboratoire de Physique des Solides, Universite Paris-Sud, F-91405 Orsay cedex, France. fayard@lps.u-psud.fr
SP englisch
PO England