Prion proteins with insertion mutations have altered N-terminal conformation and increased ligand binding activity and are more susceptible to oxidative attack.
We compared the biochemical properties of a wild type recombinant normal human cellular prion protein, rPrP(c), with a recombinant mutant human prion protein that has three additional octapeptide repeats, rPrP(8OR). Monoclonal antibodies that are specific for the N terminus of rPrP(c) react much better with rPrP(8OR) than rPrP(c), suggesting that the N terminus of rPrP(8OR) is more exposed and hence more available for antibody binding. The N terminus of PrP(c) contains a glycosaminoglycan binding motif. Accordingly, rPrP(8OR) also binds more glycosaminoglycan than rPrP(c). In addition, the divalent cation copper modulates the conformations of rPrP(c) and rPrP(8OR) differently. When compared with rPrP(c), rPrP(8OR) is also more susceptible to oxidative damage. Furthermore, the abnormalities associated with rPrP(8OR) are recapitulated, but even more profoundly, in another insertion mutant, which has five extra octapeptide repeats, rPrP(10OR). Therefore, insertion mutants appear to share common features, and the degree of abnormality is proportional to the number of insertions. Any of these anomalies may contribute to the pathogenesis of inherited human prion disease.
Yin
Shaoman
S
Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44120, USA.
Yu
Shuiliang
S
Li
Chaoyang
C
Wong
Poki
P
Chang
Binggong
B
Xiao
Fan
F
Kang
Shin-Chung
SC
Yan
Huimin
H
Xiao
Gengfu
G
Grassi
Jacques
J
Tien
Po
P
Sy
Man-Sun
MS
D020816:Amino Acid Motifs; D000911:Antibodies, Monoclonal / Q000737:chemistry; D002118:Calcium / Q000378:metabolism; D002244:Carbon / Q000737:chemistry; D002412:Cations; D003300:Copper / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D006025:Glycosaminoglycans / Q000737:chemistry; D006801:Humans; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008957:Models, Genetic; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D018621:PrPC Proteins / Q000737:chemistry; D011328:Prions / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry
D000911:Antibodies, Monoclonal; D002412:Cations; D018076:DNA, Complementary; D000939:Epitopes; D006025:Glycosaminoglycans; D008024:Ligands; D010455:Peptides; D018621:PrPC Proteins; D011328:Prions; D011994:Recombinant Proteins; D002244:Carbon; D003300:Copper; D010100:Oxygen; D002118:Calcium