Conformational intermediate of the amyloidogenic protein beta 2-microglobulin at neutral pH.
Aggregation and fibrillation of beta(2)-microglobulin are hallmarks of dialysis-related amyloidosis. We characterize perturbations of the native conformation of beta(2)-microglobulin that may precede fibril formation. For a beta(2)-microglobulin variant cleaved at lysine 58, we show using capillary electrophoresis that two conformers spontaneously exist in aqueous buffers at neutral pH. Upon treatment of wild-type beta(2)-microglobulin with acetonitrile or trifluoroethanol, two conformations were also observed. These conformations were in equilibrium dependent on the sample temperature and the percentage of organic solvent present. Circular dichroism showed a loss of beta-structures and gain of alpha-helices. Reversal to the native conformation occurred when removing the organics. Affinity capillary electrophoresis experiments showed increased specific interactions of the nonnative beta(2)-microglobulin conformation with the dyes 8-anilino-1-naphthalene sulfonic acid and Congo red. The observations may relate to early folding events prior to amyloid fibrillation and facilitate the development of methods to detect and inhibit pro-amyloid protein and peptide conformations.
Heegaard
N H
NH
Department of Autoimmunology, Statens Serum Institut, 2300 Copenhagen S, Denmark. nhe@ssi.dk
Sen
J W
JW
Kaarsholm
N C
NC
Nissen
M H
MH
D000911:Antibodies, Monoclonal; D001665:Binding Sites; D002942:Circular Dichroism; D003224:Congo Red; D014644:Genetic Variation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008239:Lysine; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D021241:Spectrometry, Mass, Electrospray Ionization; D014511:Uremia / Q000652:urine; D001613:beta 2-Microglobulin / Q000737:chemistry* / Q000302:isolation & purification / Q000652:urine
D000911:Antibodies, Monoclonal; D010446:Peptide Fragments; D001613:beta 2-Microglobulin; D003224:Congo Red; D008239:Lysine