Article (Scientific journals)
Characterization of Oligomeric Species on the Aggregation Pathway of Human Lysozyme
Frare, Erica; Mossuto, Maria F.; Polverino de Laureto, Patrizia et al.
2009In Journal of Molecular Biology, 387, p. 17-27
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Abstract :
[en] The aggregation process of wild-type human lysozyme at pH 3.0 and 60 °C has been analyzed by characterizing a series of distinct species formed on the aggregation pathway, specifically the amyloidogenic monomeric precursor protein, the oligomeric soluble prefibrillar aggregates, and the mature fibrils. Particular attention has been focused on the analysis of the structural properties of the oligomeric species, since recent studies have shown that the oligomers formed by lysozyme prior to the appearance of mature amyloid fibrils are toxic to cells. Here, soluble oligomers of human lysozyme have been analyzed by a range of techniques including binding to fluorescent probes such as thioflavin T and 1-anilino-naphthalene-8-sulfonate, Fourier transform infrared spectroscopy, and controlled proteolysis. Oligomers were isolated after 5 days of incubation of the protein and appear as spherical particles with a diameter of 8–17 nm when observed by transmission electron microscopy. Unlike the monomeric protein, oligomers have solvent-exposed hydrophobic patches able to bind the fluorescent probe 1-anilino-naphthalene-8-sulfonate. Fourier transform infrared spectroscopy spectra of oligomers are indicative of misfolded species when compared to monomeric lysozyme, with a prevalence of random structure but with significant elements of the β-sheet structure that is characteristic of the mature fibrils. Moreover, the oligomeric lysozyme aggregates were found to be more susceptible to proteolysis with pepsin than both the monomeric protein and the mature fibrils, indicating further their less organized structure. In summary, this study shows that the soluble lysozyme oligomers are locally unfolded species that are present at low concentration during the initial phases of aggregation. The nonnative conformational features of the lysozyme molecules of which they are composed are likely to be the factors that confer on them the ability to interact inappropriately with a variety of cellular components including membranes.
Disciplines :
Biochemistry, biophysics & molecular biology
Author, co-author :
Frare, Erica;  University of Padua > CRIBI Biotechnology Centre
Mossuto, Maria F.;  University of Padua > CRIBI Biotechnology Centre
Polverino de Laureto, Patrizia;  University of Padua > CRIBI Biotechnology Centre
Tolin, Serena;  University of Padua > CRIBI Biotechnology Centre
Menzer, Linda ;  Université de Liège - ULiège > CIP
Dumoulin, Mireille  ;  Université de Liège - ULiège > Département des sciences de la vie > Enzymologie et repliement des protéines
Dobson, Christopher M.
Fontana, Angelo
Language :
English
Title :
Characterization of Oligomeric Species on the Aggregation Pathway of Human Lysozyme
Publication date :
30 January 2009
Journal title :
Journal of Molecular Biology
ISSN :
0022-2836
eISSN :
1089-8638
Publisher :
Academic Press, London, United Kingdom
Volume :
387
Pages :
17-27
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 15 September 2009

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