Small angle X-ray scattering study of the yeast prion Ure2p.
The GdmCl-induced equilibrium unfolding and dissociation of the dimeric yeast prion protein Ure2, and its prion domain deletion mutants Delta 15-42Ure2 and 90Ure2, was studied by small angle X-ray scattering (SAXS) using synchrotron radiation and by chemical cross-linking with dithiobis(succinimidyl propionate) (DTSP). The native state is globular and predominantly dimeric prior to the onset of unfolding. R(g) values of 32 and 45A were obtained for the native and 5M GdmCl denatured states of Delta 15-42Ure2, respectively; the corresponding values for 90Ure2 were 2-3A lower. SAXS suggests residual structure in the 4M GdmCl denatured state and chemical cross-linking detects persistence of dimeric structure under these conditions. Hexamers consisting of globular subunits could be detected by SAXS at high protein concentration under partially denaturing conditions. The increased tendency of partially folded states to form small oligomers points to a mechanism for prion formation.
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, PR China.
Li
L
Zhu
Hiroshi
H
Kihara
Masaki
M
Kojima
Jun-Mei
JM
Zhou
Sarah
S
Perrett
D001665:Binding Sites; D019281:Dimerization; D005979:Glutathione Peroxidase; D011328:Prions / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D017356:Synchrotrons; D014961:X-Ray Diffraction / Q000379:methods*
D011328:Prions; D029701:Saccharomyces cerevisiae Proteins; D005979:Glutathione Peroxidase; C067020:URE2 protein, S cerevisiae