Wild-type Shadoo proteins convert to amyloid-like forms under native conditions.
The cellular prion protein PrP(C) refolds into a beta-sheet enriched, infectivity-associated form called PrP(Sc). Shadoo (Sho) is a newly discovered glycoprotein that is also expressed in the adult brain. Wild type (wt) mouse Sho consists of an arginine-rich region, a hydrophobic central domain of five tandem A/LAAG amino acid repeats R1-R5 with similarity to the hydrophobic domain of PrP(C), and a C-terminal domain with one N-linked carbohydrate. As some alanine-rich proteins and PrP with a shortened C-terminal domain form amyloid we investigated conformational properties of wt Sho and polymorphic variants with insertion/deletions centered on R3. Recombinant mouse and sheep Sho converted to an amyloid-like form without recourse to chemical denaturation or acidification. For wt proteins this transition was marked by increased thioflavin T binding, Congo red staining, presence of fibrillar structures by electron microscopy, formation of sodium dodecyl sulfate-resistant complexes and the generation of a C-terminal proteinase K resistant core of 5-8 kDa. Variant Sho proteins differing within the R1-R5 region exhibited most but not all of these properties. Our studies define a proteinase K -resistant signature fragment for the amyloid fold of Sho and raise the question of a physiological role for this form of the wt protein.
Daude
Nathalie
N
Centre for Prions and Protein Folding Diseases, University of Alberta, Alberta, Canada.
Ng
Vivian
V
Watts
Joel C
JC
Genovesi
Sacha
S
Glaves
John Paul
JP
Wohlgemuth
Serene
S
Schmitt-Ulms
Gerold
G
Young
Howard
H
McLaurin
Joanne
J
Fraser
Paul E
PE
Westaway
David
D
D000595:Amino Acid Sequence; D000682:Amyloid / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D003224:Congo Red; D017077:Culture Media, Conditioned / Q000494:pharmacology; D019286:Endopeptidase K / Q000494:pharmacology; D058851:GPI-Linked Proteins; D051379:Mice; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009419:Nerve Tissue Proteins / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D009447:Neuroblastoma / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018621:PrPC Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011328:Prions / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D011487:Protein Conformation / Q000187:drug effects; D017510:Protein Folding / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects; D012756:Sheep; D014162:Transfection / Q000379:methods
D000682:Amyloid; D017077:Culture Media, Conditioned; D058851:GPI-Linked Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D018621:PrPC Proteins; D011328:Prions; C523856:Sprn protein, mouse; D003224:Congo Red; D019286:Endopeptidase K