Bovine Serum Albumin protofibril-like aggregates formation: Solo but not simple mechanism

Year: 2011

Authors: Vetri V., D’Amico M., Fodera V., Leone M., Ponzoni A., Sberveglieri G., Militello V.

Autors Affiliation: Univ Palermo, Dipartimento Sci Fis & Astron, I-90123 Palermo, Italy; Consorzio Nazl Interuniv Sci Fis Mat CNISM, MeSIAM, I-90123 Palermo, Italy; Italian Natl Res Council, Inst Biophys Palermo, I-90146 Palermo, Italy; Univ Brescia, CNR, IDASC SENSOR Lab, I-25133 Brescia, Italy; Univ Brescia, Dept Chem, I-25133 Brescia, Italy; Univ Brescia, Dept Phys, I-25133 Brescia, Italy

Abstract: We report an experimental study on the model protein Bovine Serum Albumin (BSA), with the aim of elucidating the mechanisms by which a fully folded globular protein undergoes different aggregation pathways leading to the formation of amyloid fibrils or amorphous aggregates. We observe thermally induced formation of fibrillar structures at pH far from the protein isoelectric point. The increase of electrostatic repulsion results in protein destabilization and in modifications of inter and intra-molecular interactions leading to the growth of fibril-like aggregates stabilized by inter-molecular-p sheets. The aggregation kinetics is studied by means of fluorescence techniques, light scattering, Circular Dichroism (CD), infrared spectroscopy (FTIR) and Atomic Force Microscopy (AFM). Changes in protein secondary structures turn out to be the driving mechanism of the observed aggregation and they progress in parallel with the growth of Thioflavin T emission intensity and scattering signal. This concurrent behavior suggests a mutual stabilization of elongated protofibril-like structures and of protein conformational and structural changes, which lead to a more rigid and ordered structures. Our results give new insights on BSA self-assembly process in alkaline conditions clearly providing new pieces of evidences of the interplay of several and interconnected mechanisms occurring on different time and length scales. (C) 2011 Elsevier Inc. All rights reserved.

Journal/Review: ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS

Volume: 508      Pages from: 13  to: 24

More Information: This work was partially supported by a National Project (PRIN2008) of the Italian Ministry of University Research. We thank members of Molecular Biophysics and Soft Matter Group-University of Palermo (http://www.fisica.unipa.it/biophysmol) for useful discussions and Prof. M. Cannas for scientific support in fluorescence lifetime measurements.
KeyWords: Protein aggregation; Bovine Serum Albumin; Conformational changes; Fibrils; Fluorescence lifetime
DOI: 10.1016/j.abb.2011.01.024

Citations: 78
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