Solution conditions can promote formation of either amyloid protofilaments or mature fibrils from the HypF N-terminal domain.
The HypF N-terminal domain has been found to convert readily from its native globular conformation into protein aggregates with the characteristics of amyloid fibrils associated with a variety of human diseases. This conversion was achieved by incubation at acidic pH or in the presence of moderate concentrations of trifluoroethanol. Electron microscopy showed that the fibrils grown in the presence of trifluoroethanol were predominantly 3-5 nm and 7-9 nm in width, whereas fibrils of 7-9 nm and 12-20 nm in width prevailed in samples incubated at acidic pH. These results indicate that the assembly of protofilaments or narrow fibrils into mature amyloid fibrils is guided by interactions between hydrophobic residues that may remain exposed on the surface of individual protofilaments. Therefore, formation and isolation of individual protofilaments appears facilitated under conditions that favor the destabilization of hydrophobic interactions, such as in the presence of trifluoroethanol.
Chiti
F
F
Dipartimento di Scienze Biochimiche, Università degli Studi di Firenze, Viale Morgagni 50, 50134 Firenze, Italy.
Bucciantini
M
M
Capanni
C
C
Taddei
N
N
Dobson
C M
CM
Stefani
M
M
D000682:Amyloid / Q000737:chemistry*; D016229:Amyloid beta-Peptides / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D052160:Benzothiazoles; D002942:Circular Dichroism; D003001:Cloning, Molecular; D004396:Coloring Agents / Q000494:pharmacology; D003224:Congo Red / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism; D005456:Fluorescent Dyes / Q000494:pharmacology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008854:Microscopy, Electron; D017434:Protein Structure, Tertiary; D013844:Thiazoles / Q000494:pharmacology; D013997:Time Factors; D014270:Trifluoroethanol / Q000494:pharmacology; D014508:Urea / Q000494:pharmacology
D000682:Amyloid; D016229:Amyloid beta-Peptides; D001426:Bacterial Proteins; D052160:Benzothiazoles; D004396:Coloring Agents; D005456:Fluorescent Dyes; C108878:HypF protein, Bacteria; D013844:Thiazoles; C009462:thioflavin T; D003224:Congo Red; D014270:Trifluoroethanol; D014508:Urea