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Calcyclin Binding Protein/Siah-1 Interacting Protein Is a Hsp90 Binding Chaperone
Agnieszka Góral1, Paweł Bieganowski2, Wiktor Prus1
1Nencki Institute of Experimental Biology PAS, Warsaw, Poland.
Plos One
|June 2, 2016
Summary
CacyBP/SIP interacts with Hsp90, acting as a chaperone and potentially dephosphorylating it. This suggests CacyBP/SIP plays a role in regulating the Hsp90 chaperone machinery within the cell.
Area of Science:
- Molecular Biology
- Cell Biology
- Protein Biochemistry
Background:
- Heat shock protein 90 (Hsp90) is a crucial molecular chaperone whose activity is regulated by co-chaperones.
- CacyBP/SIP shares sequence homology with Sgt1, a known Hsp90 co-chaperone, prompting investigation into its interaction with Hsp90.
Purpose of the Study:
- To determine if CacyBP/SIP interacts with Hsp90.
- To elucidate the binding domain and cellular localization of CacyBP/SIP-Hsp90 complexes.
- To investigate the functional role of CacyBP/SIP in Hsp90 chaperone activity and regulation.
Main Methods:
- Immunoprecipitation assays to detect CacyBP/SIP-Hsp90 binding.
- Proximity Ligation Assay (PLA) for in situ visualization of protein complexes.
- Enzyme-Linked Immunosorbent Assay (ELISA) for direct protein interaction studies.
- In vitro chaperone assays (luciferase renaturation, citrate synthase aggregation).
- 2D electrophoresis to analyze Hsp90 modifications.
Main Results:
- CacyBP/SIP directly binds to the middle (M) domain of Hsp90.
- CacyBP/SIP-Hsp90 complexes are predominantly found in the cytoplasm.
- CacyBP/SIP exhibits intrinsic chaperone properties.
- CacyBP/SIP expression leads to more basic Hsp90 forms, suggesting dephosphorylation.
Conclusions:
- CacyBP/SIP is a novel Hsp90-interacting protein.
- CacyBP/SIP functions as a chaperone and may regulate Hsp90 activity through dephosphorylation.
- These findings identify CacyBP/SIP as a component of the Hsp90 regulatory network.
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