title: Fibrillar vs crystalline full-length beta-2-microglobulin studied by high-resolution solid-state NMR spectroscopy.
abstract: 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.
authors.affiliation: Centre de RMN à Très Hauts Champs, Université de Lyon (CNRS/ENS Lyon/UCB Lyon 1), 69100 Villeurbanne, France.
authors.forename: Emeline
authors.initials: E
authors.lastname: Barbet-Massin
authors.forename: Stefano
authors.initials: S
authors.lastname: Ricagno
authors.forename: Józef R
authors.initials: JR
authors.lastname: Lewandowski
authors.forename: Sofia
authors.initials: S
authors.lastname: Giorgetti
authors.forename: Vittorio
authors.initials: V
authors.lastname: Bellotti
authors.forename: Martino
authors.initials: M
authors.lastname: Bolognesi
authors.forename: Lyndon
authors.initials: L
authors.lastname: Emsley
authors.forename: Guido
authors.initials: G
authors.lastname: Pintacuda
mesh_terms: 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
chemical_list: D000682:Amyloid; D001613:beta 2-Microglobulin