Self-similarity properties of alpha-crystallin supramolecular aggregates

Bassi, Francesco; Arcòvito, Giuseppe; Spirito, Marco De; Mordente, Alvaro; Martorana, GE

doi:10.1016/s0006-3495(95)80143-8

Cited by 26 publications

(13 citation statements)

References 33 publications

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“…The second exponential growth, already investigated in detail [19], is consistent with an RLCA process where HMWs, of radius , after a large number of collisions can stick together. The time at which appears the crossing between these two steps it is called .…”

Section: Resultssupporting

confidence: 78%

The Thermal Structural Transition of α-Crystallin Inhibits the Heat Induced Self-Aggregation

et al. 2011

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-crystallin, the major constituent of human lens, is a member of the heat-shock proteins family and it is known to have a quaternary structural transition at . The presence of calcium ions and/or temperature changes induce supramolecular self-aggregation, a process of relevance in the cataractogenesis. Here we investigate the potential effect of the bovine -crystallin's structural transition on the self-aggregation process. Along all the temperatures investigated, aggregation proceeds by forming intermediate molecular assemblies that successively aggregate in clusters. The final morphology of the aggregates, above and below , is similar, but the aggregation kinetics are completely different. The size of the intermediate molecular assemblies, and their repulsive energy barrier show a marked increase while crossing . Our results highlight the key role of heat modified form of -crystallin in protecting from aggregation and preserving the transparency of the lens under hyperthermic conditions.

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Section: Resultssupporting

confidence: 78%

The Thermal Structural Transition of α-Crystallin Inhibits the Heat Induced Self-Aggregation

et al. 2011

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“…On-line analysis of the kinetics of protein aggregation can be carried out using dynamic light scattering (DLS). There are numerous investigations of the aggregation kinetics for different proteins, where the size of protein aggregates was estimated by DLS [ 14 , 52 , 80 , 82 – 89 ].…”

Section: Mechanisms Of Protein Aggregationmentioning

confidence: 99%

Mechanism of Suppression of Protein Aggregation by α-Crystallin

Markossian

Yudin

2009

IJMS

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This review summarizes experimental data illuminating the mechanism of suppression of heat-induced protein aggregation by -crystallin, one of the small heat shock proteins. The dynamic light scattering data show that the initial stage of thermal aggregation of proteins is the formation of the initial aggregates involving hundreds of molecules of the denatured protein. Further sticking of the starting aggregates proceeds in a regime of diffusion-limited cluster-cluster aggregation. The protective effect of -crystallin is due to transition of the aggregation process to the regime of reaction-limited cluster-cluster aggregation, wherein the sticking probability for the colliding particles becomes lower than unity.

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“…The conserved C-terminal domain of ϳ100 amino acids shares sequence homology with the major eye lens protein ␣A-crystallin (4). Almost all sHsps assemble into large oligomeric complexes of 9 to Ͼ30 subunits, and complexes in the range of 125 kDa to 2 MDa have been found (5)(6)(7)(8)(9)(10)(11). Some sHsps such as those from plants form assemblies with well defined stoichiometries, whereas other sHsps, including the mammalian proteins, form a range of oligomeric sizes (12,13).…”

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confidence: 99%

Analysis of the Interaction of Small Heat Shock Proteins with Unfolding Proteins

Stromer

Ehrnsperger

Gaestel

et al. 2003

Journal of Biological Chemistry

165

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The ubiquitous small heat shock proteins (sHsps) are efficient molecular chaperones that interact with nonnative proteins, prevent their aggregation, and support subsequent refolding. No obvious substrate specificity has been detected so far. A striking feature of sHsps is that they form large complexes with nonnative proteins. Here, we used several well established model chaperone substrates, including citrate synthase, ␣-glucosidase, rhodanese, and insulin, and analyzed their interaction with murine Hsp25 and yeast Hsp26 upon thermal unfolding. The two sHsps differ in their modes of activation. In contrast to Hsp25, Hsp26 undergoes a temperature-dependent dissociation that is required for efficient substrate binding. Our analysis shows that Hsp25 and Hsp26 reacted in a similar manner with the nonnative proteins. For all substrates investigated, complexes of defined size and shape were formed. Interestingly, several different nonnative proteins could be incorporated into defined sHsp-substrate complexes. The first substrate protein bound seems to determine the complex morphology. Thus, despite the differences in quaternary structure and mode of activation, the formation of large uniform sHsp-substrate complexes seems to be a general feature of sHsps, and this unique chaperone mechanism is conserved from yeast to mammals.In response to environmental stress such as heat shock, which leads to the accumulation of nonnative proteins, cells increase the expression of several classes of proteins (1). The major conserved families of these heat shock proteins (Hsps) 1 have been shown to be involved in protein folding as molecular chaperones (2).The most divergent of these chaperone classes are the small heat shock proteins (sHsps). sHsps have been found in almost all organisms investigated so far, with the number of members varying from species to species. They share conserved regions mostly in the C-terminal part of the protein, whereas the Nterminal part differs in sequence and length, leading to molecular masses of 16 -42 kDa for sHsps in different organisms (3). The conserved C-terminal domain of ϳ100 amino acids shares sequence homology with the major eye lens protein ␣A-crystallin (4). Almost all sHsps assemble into large oligomeric complexes of 9 to Ͼ30 subunits, and complexes in the range of 125 kDa to 2 MDa have been found (5-11). Some sHsps such as those from plants form assemblies with well defined stoichiometries, whereas other sHsps, including the mammalian proteins, form a range of oligomeric sizes (12, 13). This polydispersity has limited the amount of structural information available. The crystal structure of an archaeal sHsp (14) and the cryo-electron microscopy reconstruction of ␣B-crystallin (15) revealed that the overall organization is that of a hollow globular sphere. A variation of this scheme is the three-dimensional structure of wheat Hsp16.9, which assembles into a dodecameric double disk, where each disk is organized as a trimer of dimers (16). Many sHsps have dynamic and variable quaternary s...

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Self-similarity properties of alpha-crystallin supramolecular aggregates

Cited by 26 publications

References 33 publications

The Thermal Structural Transition of α-Crystallin Inhibits the Heat Induced Self-Aggregation

The Thermal Structural Transition of α-Crystallin Inhibits the Heat Induced Self-Aggregation

Mechanism of Suppression of Protein Aggregation by α-Crystallin

Analysis of the Interaction of Small Heat Shock Proteins with Unfolding Proteins

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