The monomer-seed interaction mechanism in the formation of the β2-microglobulin amyloid fibril clarified by solution NMR techniques.
Amyloid fibrils are proteinous aggregates associated with various diseases, including Alzheimer's disease, type II diabetes, and dialysis-related amyloidosis. It is generally thought that, during the progression of these diseases, a precursor peptide or protein assumes a partially denatured structure, which interacts with the fibril seed to change into the final amyloid form. β2-Microglobulin (β2m), associated with dialysis-related amyloidosis, is known to form amyloid fibrils at low pH via a partially structured state. However, the molecular mechanism by which the conformation of β2m changes from the precursor to the final fibril structure is poorly understood. We performed various NMR experiments to characterize acid-denatured β2m. The analysis of the transverse relaxation rates revealed that acid-denatured β2m undergoes a structural exchange with an extensively unfolded form. The results of transferred cross-saturation experiments indicated that residues with a residual structure in the acid-denatured state are associated with the interaction with the fibril seed. Our experimental data suggest the partially structured state to be "activated" to become extensively unfolded, in which state the hydrophobic residues are exposed and associate with the seed. Our results provide general information about the extension of amyloid fibrils.
Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
Kotaro
K
Yanagi
Kazumasa
K
Sakurai
Yuichi
Y
Yoshimura
Tsuyoshi
T
Konuma
Young-Ho
YH
Lee
Kenji
K
Sugase
Takahisa
T
Ikegami
Hironobu
H
Naiki
Yuji
Y
Goto
D000682:Amyloid / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000686:Amyloidosis / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012996:Solutions / Q000737:chemistry; D001613:beta 2-Microglobulin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D000682:Amyloid; D011994:Recombinant Proteins; D012996:Solutions; D001613:beta 2-Microglobulin