Secondary structure analysis of the scrapie-associated protein PrP 27-30 in water by infrared spectroscopy.
A protease-resistant form of the protein PrP (PrP-res) accumulates in tissues of mammals infected with scrapie, Creutzfeldt-Jakob disease, and related transmissible neurodegenerative diseases. This abnormal form of PrP can aggregate into insoluble amyloid-like fibrils and plaques and has been identified as the major component of brain fractions enriched for scrapie infectivity. Using a recently developed technique in Fourier transform infrared spectroscopy which allows protein conformational analysis in aqueous media, we have studied the secondary structure of the proteinase K resistant core of PrP-res (PrP-res 27-30) as it exists in highly infectious fibril preparations. Second-derivative analysis of the infrared spectra has enabled us to quantitate the relative amounts of different secondary structures in the PrP-res aggregates. The analysis indicated that PrP-res 27-30 is predominantly composed of beta-sheet (47%), which is consistent with its amyloid-like properties. In addition, significant amounts of turn (31%) and alpha-helix (17%) were identified, indicating that amyloid-like fibrils need not be exclusively beta-sheet. The infrared-based secondary structure compositions were then used as constraints to improve the theoretical localization of the secondary structures within PrP-res 27-30.
Caughey
B W
BW
NIAID, National Institutes of Health, Rocky Mountain Laboratories, Hamilton, Montana 59840.
Dong
A
A
Bhat
K S
KS
Ernst
D
D
Hayes
S F
SF
Caughey
W S
WS
D000117:Acetylglucosamine / Q000737:chemistry; D000818:Animals; D001921:Brain / Q000382:microbiology; D006224:Cricetinae; D004591:Electrophoresis, Polyacrylamide Gel; D008647:Mesocricetus; D008854:Microscopy, Electron; D008970:Molecular Weight; D018622:PrP 27-30 Protein; D011328:Prions / Q000378:metabolism*; D011487:Protein Conformation; D012608:Scrapie / Q000382:microbiology; D013055:Spectrophotometry, Infrared; D014764:Viral Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification / Q000648:ultrastructure; D014867:Water
D011328:Prions; D014764:Viral Proteins; D014867:Water; D018622:PrP 27-30 Protein; D000117:Acetylglucosamine