Hsp70 Inhibits Aggregation of IAPP by Binding to the Heterogeneous Prenucleation Oligomers
| Autor: | Mithun Maddheshiya, Bankanidhi Sahoo, Sreelakshmi Cherakara, Timir Baran Sil, Kanchan Garai, S. Deepa, Neeraja Chilukoti |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Amyloid
endocrine system 0303 health sciences Chemistry Size-exclusion chromatography Biophysics Fluorescence correlation spectroscopy Articles Intrinsically disordered proteins Oligomer Islet Amyloid Polypeptide 03 medical and health sciences chemistry.chemical_compound Amyloid disease 0302 clinical medicine Förster resonance energy transfer Monomer HSP70 Heat-Shock Proteins 030217 neurology & neurosurgery 030304 developmental biology |
| Zdroj: | Biophys J |
| ISSN: | 0006-3495 |
| DOI: | 10.1016/j.bpj.2020.12.019 |
| Popis: | Molecular chaperone Hsp70 plays important roles in the pathology of amyloid diseases by inhibiting aberrant aggregation of proteins. However, the biophysical mechanism of the interaction of Hsp70 with the intrinsically disordered proteins (IDPs) is unclear. Here, we report that Hsp70 inhibits aggregation of islet amyloid polypeptide (IAPP) at substoichiometric concentrations under diverse solution conditions, including in the absence of ATP. The inhibitory effect is strongest if Hsp70 is added in the beginning of aggregation but progressively less if added later, indicating a role for Hsp70 in preventing nucleation of IAPP. However, ensemble measurement of the binding affinity suggests poor interactions between Hsp70 and IAPP. Therefore, we hypothesize that the interaction must involve a rare species (e.g., the oligomeric intermediates of IAPP). Size exclusion chromatography and field flow fractionation are then used to fractionate the constituent species. Multiangle light scattering and fluorescence correlation spectroscopy measurements indicate that the dominant fraction in size exclusion chromatography contains a few nanomolar Hsp70-IAPP complexes amid several μmoles of free Hsp70. Using single-particle two-color coincidence detection measurements, we detected a minor fraction that exhibits fluorescence bursts arising from heterogeneous oligomeric complexes of IAPP and Hsp70. Taken together, our results indicate that Hsp70 interacts poorly with the monomers but strongly with oligomers of IAPP. This is likely a generic feature of the interactions of Hsp70 chaperones with the amyloidogenic IDPs. Whereas high-affinity interactions with the oligomers prevent aberrant aggregation, poor interaction with the monomers averts interference with the physiological functions of the IDPs. |
| Databáze: | OpenAIRE |
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