Reference : Characterization of Oligomeric Species on the Aggregation Pathway of Human Lysozyme
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
Characterization of Oligomeric Species on the Aggregation Pathway of Human Lysozyme
Frare, Erica [ > > ]
Mossuto, Maria F. [ > > ]
Polverino de Laureto, Patrizia [ > > ]
Tolin, Serena [ > > ]
Menzer, Linda [ > > ]
Dumoulin, Mireille mailto [Université de Liège - ULg > Département des sciences de la vie > Enzymologie et repliement des protéines >]
Dobson, Christopher M. [ > > ]
Fontana, Angelo [ > > ]
Journal of Molecular Biology
Academic Press
Yes (verified by ORBi)
United Kingdom
[en] 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
transforminfrared 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 solventexposed
hydrophobic patches able to bind the fluorescent probe 1-anilinonaphthalene-
8-sulfonate. Fourier transforminfrared 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.

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