Myoglobin forms amyloid fibrils by association of unfolded polypeptide segments.
Observations that beta-sheet proteins form amyloid fibrils under at least partially denaturing conditions has raised questions as to whether these fibrils assemble by docking of preformed beta-structure or by association of unfolded polypeptide segments. By using alpha-helical protein apomyoglobin, we show that the ease of fibril assembly correlates with the extent of denaturation. By contrast, monomeric beta-sheet intermediates could not be observed under the conditions of fibril formation. These data suggest that amyloid fibril formation from apomyoglobin depends on disordered polypeptide segments and conditions that are selectively unfavorable to folding. However, it is inevitable that such conditions often stabilize protein folding intermediates.
Fändrich
Marcus
M
Institut für Molekulare Biotechnologie, Beutenbergstrasse 11, D-07745 Jena, Germany. fandrich@imb-jena.de
Forge
Vincent
V
Buder
Katrin
K
Kittler
Marlis
M
Dobson
Christopher M
CM
Diekmann
Stephan
S
D000595:Amino Acid Sequence; D000818:Animals; D006736:Horses; D008969:Molecular Sequence Data; D009210:Myofibrils / Q000737:chemistry*; D009211:Myoglobin / Q000737:chemistry* / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D011489:Protein Denaturation; D017510:Protein Folding; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014961:X-Ray Diffraction
D009211:Myoglobin; D010455:Peptides