Fibrillar vs crystalline full-length beta-2-microglobulin studied by high-resolution solid-state NMR spectroscopy.
Elucidating the fine structure of amyloid fibrils as well as understanding their processes of nucleation and growth remains a difficult yet essential challenge, directly linked to our current poor insight into protein misfolding and aggregation diseases. Here we consider beta-2-microglobulin (beta2m), the MHC-1 light chain component responsible for dialysis-related amyloidosis, which can give rise to amyloid fibrils in vitro under various experimental conditions, including low and neutral pH. We have used solid-state NMR to probe the structural features of fibrils formed by full-length beta2m (99 residues) at pH 2.5 and pH 7.4. A close comparison of 2D (13)C-(13)C and (15)N-(13)C correlation experiments performed on beta2m, in both the crystalline and fibrillar states, suggests that, in spite of structural changes affecting the protein loops linking the protein beta-strands, the protein chain retains a substantial share of its native secondary structure in the fibril assembly. Moreover, variations in the chemical shifts of the key Pro32 residue suggest the involvement of a cis-trans isomerization in the process of beta2m fibril formation. Lastly, the analogy of the spectra recorded on beta2m fibrils grown at different pH values hints at a conserved architecture of the amyloid species thus obtained.
Barbet-Massin
Emeline
E
Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100 Villeurbanne, France.
Ricagno
Stefano
S
Lewandowski
Józef R
JR
Giorgetti
Sofia
S
Bellotti
Vittorio
V
Bolognesi
Martino
M
Emsley
Lyndon
L
Pintacuda
Guido
G
D000682:Amyloid / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D001613:beta 2-Microglobulin / Q000737:chemistry* / Q000378:metabolism
D000682:Amyloid; D001613:beta 2-Microglobulin