Characterization of prion protein (PrP)-derived peptides that discriminate full-length PrPSc from PrPC.
On our initial discovery that prion protein (PrP)-derived peptides were capable of capturing the pathogenic prion protein (PrP(Sc)), we have been interested in how these peptides interact with PrP(Sc). After screening peptides from the entire human PrP sequence, we found two peptides (PrP(19-30) and PrP(100-111)) capable of binding full-length PrP(Sc) in plasma, a medium containing a complex mixture of other proteins including a vast excess of the normal prion protein (PrP(C)). The limit of detection for captured PrP(Sc) was calculated to be 8 amol from a approximately 10(5)-fold dilution of 10% (wt/vol) human variant Creutzfeldt-Jakob disease brain homogenate, with >3,800-fold binding specificity to PrP(Sc) over PrP(C). Through extensive analyses, we show that positively charged amino acids play an important, but not exclusive, role in the interaction between the peptides and PrP(Sc). Neither hydrophobic nor polar interactions appear to correlate with binding activity. The peptide-PrP(Sc) interaction was not sequence-specific, but amino acid composition affected binding. Binding occurs through a conformational domain that is only present in PrP(Sc), is species-independent, and is not affected by proteinase K digestion. These and other findings suggest a mechanism by which cationic domains of PrP(C) may play a role in the recruitment of PrP(C) to PrP(Sc).
Lau
Anthony L
AL
Novartis Vaccines and Diagnostics, Inc., 4560 Horton Street, Emeryville, CA 94608, USA.
Yam
Alice Y
AY
Michelitsch
Melissa M D
MM
Wang
Xuemei
X
Gao
Carol
C
Goodson
Robert J
RJ
Shimizu
Robert
R
Timoteo
Gulliver
G
Hall
John
J
Medina-Selby
Angelica
A
Coit
Doris
D
McCoin
Colin
C
Phelps
Bruce
B
Wu
Ping
P
Hu
Celine
C
Chien
David
D
Peretz
David
D
D000906:Antibodies / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D008863:Microspheres; D010446:Peptide Fragments / Q000097:blood / Q000138:chemical synthesis* / Q000276:immunology; D018621:PrPC Proteins / Q000097:blood / Q000138:chemical synthesis* / Q000145:classification / Q000276:immunology; D018620:PrPSc Proteins / Q000097:blood / Q000138:chemical synthesis* / Q000145:classification / Q000276:immunology; D017096:Prion Diseases / Q000175:diagnosis / Q000276:immunology; D011485:Protein Binding
D000906:Antibodies; D007074:Immunoglobulin G; D010446:Peptide Fragments; D018621:PrPC Proteins; D018620:PrPSc Proteins