Topological investigation of amyloid fibrils obtained from β2-microglobulin
| Autor: | Anne Clark, Vittorio Bellotti, Serena Principe, Gianpaolo Merlini, Maria Chiara Monti, Piero Pucci, Angela Amoresano, Sofia Giorgetti, Palma Mangione |
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| Přispěvatelé: | Monti, Maria, Principe, S, Giorgetti, S, Mangione, P, Merlini, G, Clark, A, Bellotti, V, Amoresano, Angela, Pucci, Pietro |
| Jazyk: | angličtina |
| Rok vydání: | 2002 |
| Předmět: |
Proteases
Amyloid Proteolysis macromolecular substances Fibril Biochemistry Article Mass Spectrometry amyloid fibril Endopeptidases medicine Chymotrypsin Humans Molecular Biology Chromatography High Pressure Liquid amyloidosi biology medicine.diagnostic_test Beta-2 microglobulin Chemistry Amyloidosis Metalloendopeptidases medicine.disease In vitro Microscopy Electron limited proteolysi biology.protein Biophysics beta 2-Microglobulin |
| Popis: | Amyloid fibrils of patients treated with regular hemodialysis essentially consists of beta2-microglobulin (beta2-m) and its truncated species DeltaN6beta2-m lacking six residues at the amino terminus. The truncated fragment has a more flexible three-dimensional structure and constitutes an excellent candidate for the analysis of a protein in the amyloidogenic conformation. The surface topology of synthetic fibrils obtained from intact beta2-m and truncated DeltaN6beta2-m was investigated by the limited proteolysis/mass spectrometry approach that appeared particularly suited to gain insights into the structure of beta2-m within the fibrillar polymer. The distribution of prefential proteolytic sites observed in both fibrils revealed that the central region of the protein, which had been easily cleaved in the full-length globular beta2-m, was fully protected in the fibrillar form. In addition, the amino- and carboxy-terminal regions of beta2-m became exposed to the solvent in the fibrils, whereas they were masked completely in the native protein. These data indicate that beta2-m molecules in the fibrils consist of an unaccessible core comprising residues 20-87 with the strands I and VIII being not constrained in the fibrillar polymer and exposed to the proteases. Moreover, proteolytic cleavages observed in vitro at Lys 6 and Lys 19 reproduce specific cleavages that have to occur in vivo to generate the truncated forms of beta2-m occurring in natural fibrils. On the basis of these data, a possible mechanism for fibril formation from native beta2-m is discussed and an explanation for the occurrence of truncated protein species in natural fibrils is given. |
| Databáze: | OpenAIRE |
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