Ultrastructural organization of ex vivo amyloid fibrils formed by the apolipoprotein A-I Leu174Ser variant: an atomic force microscopy study.
Atomic force microscopy was employed to study ex vivo amyloid material isolated from the transplanted hearts of two patients affected by systemic amyloidosis caused by the Leu174Ser apolipoprotein A-I variant. The purified material consists of fibrils and globular aggregates. For both patients the same morphological patterns are observed; in addition, fibril diameters obtained for the two patients turn out to be compatible, both in air (2.00+/-0.02 and 2.04+/-0.04 nm) and under liquid (10.7+/-0.4 and 11.3+/-0.5 nm). Fibrils display heterogeneous morphologies, occasionally showing a left-handed twist. Inspection of fibril ends, the study of fibril contour shape and the analysis of partially unfolded fibrils yield independent evidences suggesting that most twisted fibrils are composed of three protofilaments. The size of globular aggregates is the same for both patients (4.4+/-0.4 and 5.1+/-0.5 nm, measured under liquid) and is compatible with the protofilament expected diameter, suggesting that globules may represent protofilament precursors.
Relini
Annalisa
A
National Institute for the Physics of Matter and Department of Physics, University of Genoa, via Dodecaneso 33, I-16146, Genoa, Italy. relini@fisica.unige.it
Rolandi
Ranieri
R
Bolognesi
Martino
M
Aboudan
Manuela
M
Merlini
Giampaolo
G
Bellotti
Vittorio
V
Gliozzi
Alessandra
A
D000682:Amyloid / Q000378:metabolism / Q000648:ultrastructure*; D028226:Amyloidosis, Familial / Q000235:genetics / Q000473:pathology; D016632:Apolipoprotein A-I / Q000235:genetics*; D014644:Genetic Variation; D006801:Humans; D066298:In Vitro Techniques; D018625:Microscopy, Atomic Force; D009206:Myocardium / Q000378:metabolism
D000682:Amyloid; D016632:Apolipoprotein A-I