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Proc Natl Acad Sci U S A. 2011 Jan 25;108(4):1314-9. doi: 10.1073/pnas.1008560108. Epub 2011 Jan 10.

Atomic structure of a nanobody-trapped domain-swapped dimer of an amyloidogenic beta2-microglobulin variant.

Author information

1
Department of Molecular and Cellular Interactions, Vlaams Instituut voor Biotechnologie, Pleinlaan 2, B-1050 Brussels, Belgium.

Abstract

Atomic-level structural investigation of the key conformational intermediates of amyloidogenesis remains a challenge. Here we demonstrate the utility of nanobodies to trap and characterize intermediates of β2-microglobulin (β2m) amyloidogenesis by X-ray crystallography. For this purpose, we selected five single domain antibodies that block the fibrillogenesis of a proteolytic amyloidogenic fragment of β2m (ΔN6β2m). The crystal structure of ΔN6β2m in complex with one of these nanobodies (Nb24) identifies domain swapping as a plausible mechanism of self-association of this amyloidogenic protein. In the swapped dimer, two extended hinge loops--corresponding to the heptapetide NHVTLSQ that forms amyloid in isolation--are unmasked and fold into a new two-stranded antiparallel β-sheet. The β-strands of this sheet are prone to self-associate and stack perpendicular to the direction of the strands to build large intermolecular β-sheets that run parallel to the axis of growing oligomers, providing an elongation mechanism by self-templated growth.

PMID:
21220305
PMCID:
PMC3029709
DOI:
10.1073/pnas.1008560108
[Indexed for MEDLINE]
Free PMC Article
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