Author
Cristian Ionescu-Zanetti
Other affiliations: University of California, Santa Barbara
Bio: Cristian Ionescu-Zanetti is an academic researcher from University of California, Santa Cruz. The author has contributed to research in topics: Fibril & Amyloid. The author has an hindex of 8, co-authored 9 publications receiving 1924 citations. Previous affiliations of Cristian Ionescu-Zanetti include University of California, Santa Barbara.
Topics: Fibril, Amyloid, Polymer blend, Polarization (waves), Magnetic field
Papers
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TL;DR: The data suggests that the micelles of thioflavin T bind amyloid fibrils leading to enhancement of fluorescence emission, which suggests that positive charge on the thioFlavin T molecule has a role in its micelle formation that then bind the amyloids fibril.
770 citations
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TL;DR: The data support the hypothesis that amyloid fibril formation involves the ordered self-assembly of partially folded species that are critical soluble precursors of fibrils.
Abstract: Light chain, or AL, amyloidosis is a pathological condition arising from systemic extracellular deposition of monoclonal immunoglobulin light chain variable domains in the form of insoluble amyloid fibrils, especially in the kidneys. Substantial evidence suggests that amyloid fibril formation from native proteins occurs via a conformational change leading to a partially folded intermediate conformation, whose subsequent association is a key step in fibrillation. In the present investigation, we have examined the properties of a recombinant amyloidogenic light chain variable domain, SMA, to determine whether partially folded intermediates can be detected and correlated with aggregation. The results from spectroscopic and hydrodynamic measurements, including far- and near-UV circular dichroism, FTIR, NMR, and intrinsic tryptophan fluorescence and small-angle X-ray scattering, reveal the build-up of two partially folded intermediate conformational states as the pH is decreased (low pH destabilized the protein and accelerated the kinetics of aggregation). A relatively nativelike intermediate, I(N), was observed between pH 4 and 6, with little loss of secondary structure, but with significant tertiary structure changes and enhanced ANS binding, indicating exposed hydrophobic surfaces. At pH below 3, we observed a relatively unfolded, but compact, intermediate, I(U), which was characterized by decreased tertiary and secondary structure. The I(U) intermediate readily forms amyloid fibrils, whereas I(N) preferentially leads to amorphous aggregates. Except at pH 2, where negligible amorphous aggregate is formed, the amorphous aggregates formed significantly more rapidly than the fibrils. This is the first indication that different partially folded intermediates may be responsible for different aggregation pathways (amorphous and fibrillar). The data support the hypothesis that amyloid fibril formation involves the ordered self-assembly of partially folded species that are critical soluble precursors of fibrils.
308 citations
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TL;DR: It is proposed that the hierarchical assembly model describes a general mechanism of assembly for all amyloid fibrils.
299 citations
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TL;DR: In the present investigation, the in vitro assembly of a recombinant amyloidogenic light chain variable domain, SMA, on various surfaces was monitored using atomic force microscopy and the mechanism of fibril formation on the surfaces was significantly different from in solution.
245 citations
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TL;DR: The fibrils and protofibrils showed a braided structure, suggesting that their formation involves the winding of protofibils and filaments, respectively, which support a model in which two filaments combine to form a protofafibril, two prot ofibrils intertwine toform a type I fibrill, and three filaments form a type II fibril.
Abstract: Aggregation of Ig light chains to form amyloid fibrils is a characteristic feature of light-chain amyloidosis, a light-chain deposition disease. A recombinant variable domain of the light chain SMA was used to form amyloid fibrils in vitro. Fibril formation was monitored by atomic force microscopy imaging. Single filaments 2.4 nm in diameter were predominant at early times; protofibrils 4.0 nm in diameter were predominant at intermediate times; type I and type II fibrils 8.0 nm and 6.0 nm in diameter, respectively, were predominant at the endpoints. The increase in number of fibrils correlated with increased binding of the fluorescent dye thioflavin T. The fibrils and protofibrils showed a braided structure, suggesting that their formation involves the winding of protofibrils and filaments, respectively. These observations support a model in which two filaments combine to form a protofibril, two protofibrils intertwine to form a type I fibril, and three filaments form a type II fibril.
195 citations
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TL;DR: The relative importance of the common main-chain and side-chain interactions in determining the propensities of proteins to aggregate is discussed and some of the evidence that the oligomeric fibril precursors are the primary origins of pathological behavior is described.
Abstract: Peptides or proteins convert under some conditions from their soluble forms into highly ordered fibrillar aggregates. Such transitions can give rise to pathological conditions ranging from neurodegenerative disorders to systemic amyloidoses. In this review, we identify the diseases known to be associated with formation of fibrillar aggregates and the specific peptides and proteins involved in each case. We describe, in addition, that living organisms can take advantage of the inherent ability of proteins to form such structures to generate novel and diverse biological functions. We review recent advances toward the elucidation of the structures of amyloid fibrils and the mechanisms of their formation at a molecular level. Finally, we discuss the relative importance of the common main-chain and side-chain interactions in determining the propensities of proteins to aggregate and describe some of the evidence that the oligomeric fibril precursors are the primary origins of pathological behavior.
5,897 citations
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TL;DR: Theoretical and experimental approaches to the characterization of crowding- and confinement-induced effects in systems approaching the complexity of living organisms are suggested.
Abstract: Expected and observed effects of volume exclusion on the free en- ergy of rigid and flexible macromolecules in crowded and confined systems, and consequent effects of crowding and confinement on macromolecular reaction rates and equilibria are summarized. Find- ings from relevant theoretical/simulation and experimental literature published from 2004 onward are reviewed. Additional complexity arising from the heterogeneity of local environments in biological media, and the presence of nonspecific interactions between macro- molecules over and above steric repulsion, are discussed. Theoretical and experimental approaches to the characterization of crowding- and confinement-induced effects in systems approaching the com- plexity of living organisms are suggested.
1,891 citations
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TL;DR: The molecular basis of various types of amyloidosis is reviewed and new ways of treating these disorders are proposed.
Abstract: Amyloidosis affects millions of people, as a cause of Alzheimer's disease or a complication of dialysis, and also causes rare conditions. The many forms of the disorder have one underlying principle: misfolded proteins. Prompt, correct diagnosis is essential, especially in the inherited forms of amyloidosis. This article reviews the molecular basis of various types of amyloidosis and proposes new ways of treating these disorders.
1,650 citations
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TL;DR: Recent progress in the understanding of ThT-fibril interactions at an atomic resolution is reviewed to offer guidance for designing the next generation of amyloid assembly diagnostics, inhibitors, and therapeutics.
1,580 citations
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TL;DR: The purpose of the current review is to provide a fundamental understanding of the mechanisms by which proteins aggregate and by which varying solution conditions, such as temperature, pH, salt type, salt concentration, cosolutes, preservatives, and surfactants, affect this process.
Abstract: Irreversible protein aggregation is problematic in the biotechnology industry, where aggregation is encountered throughout the lifetime of a therapeutic protein, including during refolding, purification, sterilization, shipping, and storage processes. The purpose of the current review is to provide a fundamental understanding of the mechanisms by which proteins aggregate and by which varying solution conditions, such as temperature, pH, salt type, salt concentration, cosolutes, preservatives, and surfactants, affect this process.
1,359 citations