Substrate specificity in the context of molecular chaperones

Bose, Deepak; Chakrabarti, Abhijit

doi:10.1002/iub.1656

Cited by 27 publications

(18 citation statements)

References 134 publications

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“…It is plausible to think of the chaperone potential of spectrin fragments to be driven by the presence of surface exposed hydrophobic patches, as is the case with many chaperones (Reddy, Kumar, & Kumar, ; Xu et al, ), for example the chaperones such as sHSPs and GroEL also act with the help of exposed hydrophobic patches (Haslbeck, ; Lin, Schwartz, & Eisenstein, ). It is known that chaperones act by recognizing the exposed hydrophobic clusters in structurally perturbed, misfolded, partially folded or stressed proteins with the help of hydrophobic patches of their own (Bose & Chakrabarti, ). As we have confirmed the presence of hydrophobic patches on all the spectrin domains and have determined that they all have about the same hydrophobicity it is reasonable to think that they are the determining factor in chaperone activity.…”

Section: Discussionmentioning

confidence: 99%

“…It is known that all chaperones have some features in common which aid in substrate recognition; most often, these are charged and/or hydrophobic patches which are solvent exposed (Bose & Chakrabarti, ). Keeping in mind the known presence of hydrophobic patches on spectrin as well as our hypothesis linking hydrophobic patches to chaperone activity (Bhattacharyya et al, ; Haque, Ray, & Chakrabarti, ), the most likely loci on spectrin to harbor chaperone activity should also have hydrophobic patches.…”

Section: Introductionmentioning

confidence: 99%

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Localizing the chaperone activity of erythroid spectrin

Bose

Chakrabarti

2019

Cytoskeleton

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Spectrin, the major protein of the erythrocyte membrane skeleton has canonically been thought to only serve a structural function. We have previously described a novel chaperone‐like property of spectrin and also hypothesized that the chaperone activity and binding of a hydrophobic ligand, Prodan are localized in the self‐association domain. Here we probe the location and molecular origin of the chaperone activity of multi‐domain spectrin using a selection of individual recombinant spectrin domains, which we have characterized using intrinsic tryptophan fluorescence and CD spectroscopy to show their identity to native spectrin. Aggregation assays using insulin, ADH, α‐ and β‐globin as well as enzyme refolding assays using alkaline phosphatase and α‐glucosidase show that the chaperone activity is not only localized in the self‐association domain but is a generalized property of spectrin domains. This is to our understanding, a unique feature in the case of modular multi‐repeat proteins, possibly implicating that the large family of “spectrin‐repeat” domain containing proteins may also have chaperone like property. Substrate selectivity of chaperone activity as evidenced by the preferential protection of α‐ over β‐globin chains is seen; which has implications in hemoglobin diseases. Moreover, enzyme‐refolding assays also indicate alternate modes of chaperone action. We propose that the molecular origin of chaperone activity resides in the surface exposed hydrophobic patches of the spectrin domains as shown by ANS (1‐anilinonaphthalene‐8‐sulfonic acid) and Prodan (6‐propionyl‐2[dimethylamino]‐naphthalene) binding. We also show that Prodan does indeed have a unique binding site on spectrin located at the self‐association domain.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Localizing the chaperone activity of erythroid spectrin

Bose

Chakrabarti

2019

Cytoskeleton

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“…It is plausible to think of the chaperone potential of spectrin fragments to be driven by the presence of surface exposed hydrophobic patches, as is the case with many chaperones (65,66), for example the chaperones such as sHSPs and GroEL also act with the help of exposed hydrophobic patches (67,68). It is known that chaperones act by recognizing the exposed hydrophobic clusters in structurally perturbed, misfolded, partially folded or stressed proteins with the help of hydrophobic patches of their own (29). As we have confirmed the presence of hydrophobic patches on all the spectrin domains and have determined that they all have about the same hydrophobicity it is reasonable to think that they are the determining factor in chaperone activity.…”

Section: Discussionmentioning

confidence: 99%

“…It is known that all chaperones have some features in common which aid in substrate recognition; most often these are charged and/or hydrophobic patches which are solvent exposed (29). Keeping in mind the known presence of hydrophobic patches on spectrin as well as our hypothesis linking hydrophobic patches to chaperone activity (20,30), the most likely loci on spectrin to harbour chaperone activity should also have hydrophobic patches.…”

Section: Introductionmentioning

confidence: 90%

Localizing the chaperone activity of erythroid spectrin

Bose

Chakrabarti

2019

Preprint

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Spectrin, the major protein of the RBC membrane skeleton has canonically been thought to only serve a structural function. We have described a novel chaperone-like property of spectrin and have shown that it is able to prevent the aggregation of other proteins such as alcohol dehydrogenase, insulin and free globin chains. We have tried to localize the molecular origin of chaperonelike activity in multi-domain spectrin by using recombinant spectrin fragments and investigating individual domains. We have characterized the recombinant domains using intrinsic tryptophan fluorescence and CD spectroscopy to show their identity to native spectrin. Hydrophobic ligands Prodan (6propionyl-2[dimethylamino]-naphthalene) and ANS (1-anilinonaphthalene-8-sulfonic acid) binding has been used to probe the hydrophobicity of the recombinant domains and it is seen that all domains have surface exposed hydrophobic patches; and in accordance with our previous hypothesis only the reconstituted self-association domain binds Prodan. Recombinant domains display comparable chaperone potential in preventing protein aggregation; and substrate selectivity of α-over β-globin is seen. Enzyme refolding studies show alternate pathways of chaperone action. Our current study points to the presence of hydrophobic patches on the surface of these domains as the source of the chaperone activity of spectrin, as notably seen in the self-association domain. There is no one domain largely responsible for the chaperone activity of spectrin; rather all domains appear to contribute equally, such that the chaperone activity of spectrin seems to be a linear sum of the individual activities of the domains.

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“…The action of molecular chaperones Hsp70/Hsp90 is mediated by the cochaperones, proteins interacting with molecular chaperones and providing their functional specificity. 30 Disruption of specific protein-protein interactions within molecular chaperone network would not elicit major disturbance in molecular chaperone system. Here, we described development of inhibitors of molecular interaction between Hsp70/ Hsp90 and Tom70 a mitochondrial protein import receptor and TPR domain co-chaperone.…”

Section: Discussionmentioning

confidence: 99%

Development of GMP‐1 a molecular chaperone network modulator protecting mitochondrial function and its assessment in fly and mice models of Alzheimer's disease

Pavlov

Hutter‐Paier

Havas³

et al. 2018

J Cellular Molecular Medi

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Mitochondrial dysfunction is an early feature of Alzheimer's disease (AD) and may play an important role in the pathogenesis of disease. It has been shown that amyloid beta peptide (Aβ) and amyloid precursor protein (APP) interact with mitochondria contributing to the mitochondrial dysfunction in AD. Prevention of abnormal protein targeting to mitochondria can protect normal mitochondrial function, increase neuronal survival and at the end, ameliorate symptoms of AD and other neurodegenerative disorders. First steps of mitochondrial protein import are coordinated by molecular chaperones Hsp70 and Hsp90 that bind to the newly synthesized mitochondria‐destined proteins and deliver them to the protein import receptors on the surface of organelle. Here, we have described the development of a novel compound named GMP‐1 that disrupts interactions between Hsp70/Hsp90 molecular chaperones and protein import receptor Tom70. GMP‐1 treatment of SH‐SY5Y cells results in decrease in mitochondria‐associated APP and protects SH‐SY5Y cells from toxic effect of Aβ1‐42 exposure. Experiments in drosophila and mice models of AD demonstrated neuroprotective effect of GMP‐1 treatment, improvement in memory and behaviour tests as well as restoration of mitochondrial function.

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Substrate specificity in the context of molecular chaperones

Cited by 27 publications

References 134 publications

Localizing the chaperone activity of erythroid spectrin

Localizing the chaperone activity of erythroid spectrin

Localizing the chaperone activity of erythroid spectrin

Development of GMP‐1 a molecular chaperone network modulator protecting mitochondrial function and its assessment in fly and mice models of Alzheimer's disease

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