[30] Lens α-crystallin: Chaperone-like properties

Horwitz, Joseph; Huang, Qingling; Ding, Linlin; Bova, Michael P.

doi:10.1016/s0076-6879(98)90032-5

Cited by 214 publications

(171 citation statements)

References 27 publications

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“…residues 84 -176 (Hsp27core), was a kind gift from Professor A. Laganowsky (Texas A&M Health Science Center, USA). All recombinant proteins were expressed in Escherichia coli BL21(DE3), previously transformed with each plasmid, and purified as described previously (23,67,68). Protein molecular mass standards used in gel electrophoresis were Protein Precision Plus Dual Colour obtained from Bio-Rad Laboratories (Hercules, USA), and dithiothreitol (DTT) was purchased from Amresco (Solon, USA).…”

Section: Methodsmentioning

confidence: 99%

The small heat shock protein Hsp27 binds α-synuclein fibrils, preventing elongation and cytotoxicity

Cox

Whiten

Brown

et al. 2018

Journal of Biological Chemistry

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Section: Methodsmentioning

confidence: 99%

The small heat shock protein Hsp27 binds α-synuclein fibrils, preventing elongation and cytotoxicity

Cox

Whiten

Brown

et al. 2018

Journal of Biological Chemistry

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“…residues 68 -153 (␣B-c core ), was a kind gift from Professor A. Laganowsky (Texas A&M Health Science Center). All recombinant proteins were expressed in Escherichia coli BL21(DE3) cells transformed with each plasmid, and purified as described previously (12,88,89). Dithiothreitol (DTT) was purchased from Amresco (Solon, OH), and protein molecular mass standards used in gel electrophoresis were Protein Precision Plus Dual Color obtained from Bio-Rad Laboratories.…”

Section: Methodsmentioning

confidence: 99%

Small Heat-shock Proteins Prevent α-Synuclein Aggregation via Transient Interactions and Their Efficacy Is Affected by the Rate of Aggregation

Cox

Selig

Griffin

et al. 2016

Journal of Biological Chemistry

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The aggregation of ␣-synuclein (␣-syn) into amyloid fibrils is associated with neurodegenerative diseases, collectively referred to as the ␣-synucleinopathies. In vivo, molecular chaperones, such as the small heat-shock proteins (sHsps), normally act to prevent protein aggregation; however, it remains to be determined how aggregation-prone ␣-syn evades sHsp chaperone action leading to its disease-associated deposition. This work examines the molecular mechanism by which two canonical sHsps, ␣B-crystallin (␣B-c) and Hsp27, interact with aggregation-prone ␣-syn to prevent its aggregation in vitro. Both sHsps are very effective inhibitors of ␣-syn aggregation, but no stable complex between the sHsps and ␣-syn was detected, indicating that the sHsps inhibit ␣-syn aggregation via transient interactions. Moreover, the ability of these sHsps to prevent ␣-syn aggregation was dependent on the kinetics of aggregation; the faster the rate of aggregation (shorter the lag phase), the less effective the sHsps were at inhibiting fibril formation of ␣-syn. Thus, these findings indicate that the rate at which ␣-syn aggregates in cells may be a significant factor in how it evades sHsp chaperone action in the ␣-synucleinopathies.

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“…The resuspended cultures were disrupted by sonication, and the DNA was precipitated by the addition of 0.017% polyethyleneimine. The lysates were then centrifuged at 15,000 ϫ g. ␣B-crystallin and its single variants were purified using anion exchange chromatography followed by size exclusion chromatography as described previously (6). ␣B-D2 and ␣B-D3 were loaded on a Source Q column, washed with buffer A (20 mM Tris, 100 mM NaCl, 0.1 mM EDTA, pH 8.0), and eluted with a gradient of 0.1-1 M NaCl in buffer A.…”

Section: Methodsmentioning

confidence: 99%

Mechanism of Chaperone Function in Small Heat-shock Proteins

Koteiche

Mchaourab

2003

Journal of Biological Chemistry

101

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The consequences of ␣B-crystallin phosphorylation on its chaperone activity were investigated using a detailed analysis of the recognition and binding of destabilized T4 lysozyme (T4L) mutants by ␣B-crystallin phosphorylation mimics containing combinations of serine to aspartate substitutions. The T4L site-directed mutants were selected to constitute an energetic ladder of progressively destabilized proteins having similar structures in the folded state. ␣B-crystallin and its variants differentially recognize the T4L mutants, binding the more destabilized ones to a larger extent. Furthermore, the aspartate substitutions result in an increase in the extent of binding to the same T4L mutant and in the appearance of biphasic binding isotherms. The latter indicates the presence of two modes of binding characterized by different affinities and different numbers of binding sites. The transition to two-mode binding can also be induced by temperature or pH activation of the second mode. The similarity between the phosphorylation, pH, and temperature effects suggests a common structural origin. The location of the phosphorylation sites in the N-terminal domain and the hypothesized burial of this domain in the core of the oligomeric structure are consistent with a critical role for the destabilization of the quaternary structure in the process of recognition and binding by small heat-shock proteins.Lens transparency is the consequence of a unique molecular architecture that involves the packing of three families of proteins, the crystallins, in a glass-like state (1-3). One of these families, consisting of the two highly homologous proteins ␣A-crystallin and ␣B-crystallin, belongs to the small heat-shock protein (sHSP) 1 superfamily of chaperones and shares the common structural and functional characteristics of the superfamily (4 -6). sHSP form oligomeric complexes that recognize and bind non-native protein states without the hydrolysis of ATP. The binding capacity is remarkably high with reported stoichiometries that approach one substrate of equal molecular mass per sHSP subunit. Current models of lens transparency hypothesize a critical role of the chaperone function of ␣-crystallins in delaying aggregation of damaged proteins and the onset of opacity in the fiber cells that lack the machineries necessary for protein turnover (3, 7).One of the two ␣-crystallin subunits, ␣B-crystallin, is also widely expressed in other tissues such as cardiac (8) and skeletal muscles and the brain (9, 10), where it appears to be involved in transduction pathways activated during growth and differentiation and in response to various forms of stress (11). Evidence for the participation of ␣B-crystallin and other mammalian sHSP in these pathways includes their phosphorylation by mitogen-activated protein kinase-activated protein kinases (12-15). ␣B-crystallin is phosphorylated at three serine residues during ischemia and in response to cytotoxic signals and mitogenic and inflammatory agents (16,17). Phosphorylation is presumably used to m...

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[30] Lens α-crystallin: Chaperone-like properties

Cited by 214 publications

References 27 publications

The small heat shock protein Hsp27 binds α-synuclein fibrils, preventing elongation and cytotoxicity

The small heat shock protein Hsp27 binds α-synuclein fibrils, preventing elongation and cytotoxicity

Small Heat-shock Proteins Prevent α-Synuclein Aggregation via Transient Interactions and Their Efficacy Is Affected by the Rate of Aggregation

Mechanism of Chaperone Function in Small Heat-shock Proteins

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