bi2004894_si_001.pdf (569.35 kB)
Structural Insights into the Pre-Amyloid Tetramer of β-2-Microglobulin from Covalent Labeling and Mass Spectrometry
journal contribution
posted on 2011-08-09, 00:00 authored by Vanessa
Leah Mendoza, Mario A. Barón-Rodríguez, Cristian Blanco, Richard W. VachetThe main pathogenic process underlying dialysis-related
amyloidosis is the accumulation of β-2-microglobulin (β2m)
as amyloid fibrils in the musculoskeletal system, and some evidence
suggests that Cu(II) may play a role in β2m amyloid formation.
Cu(II)-induced β2m fibril formation is preceded by the formation
of discrete, oligomeric intermediates, including dimers, tetramers,
and hexamers. In this work, we use selective covalent labeling reactions
combined with mass spectrometry to investigate the amino acids responsible
for mediating tetramer formation in wild-type β2m. By comparing
the labeling patterns of the monomer, dimer, and tetramer, we find
evidence that the tetramer interface is formed by the interaction
of D strands from one dimer unit and G strands from another dimer
unit. These covalent labeling data along with molecular dynamics calculations
allow the construction of a tetramer model that indicates how the
protein might proceed to form even higher-order oligomers.