Cited by 84Heat shock proteins researchUbiquitin and proteasome pathwaysFungal and yeast genetics research

p23/Sba1p protects against Hsp90 inhibitors independently of its intrinsic chaperone activity

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Forafonov, Fedor, Toogun, Oyetunji A., Grad, Iwona, Suslova, Elena, Freeman, Brian C., Picard, Didier·2008·Molecular and Cellular Biology

Abstract

The molecular chaperone Hsp90 assists a subset of cellular proteins and is essential in eukaryotes. A cohort of cochaperones contributes to and regulates the multicomponent Hsp90 machine. Unlike the biochemical activities of the cochaperone p23, its in vivo functions and the structure-function relationship remain poorly understood, even in the genetically tractable model organism Saccharomyces cerevisiae. The SBA1 gene that encodes the p23 ortholog in this species is not an essential gene. We found that in the absence of p23/Sba1p, yeast and mammalian cells are hypersensitive to Hsp90 inhibitors. This protective function of Sba1p depends on its abilities to bind Hsp90 and to block the Hsp90 ATPase and inhibitor binding. In contrast, the protective function of Sba1p does not require the Hsp90-independent molecular chaperone activity of Sba1p. The structure-function analysis suggests that Sba1p undergoes considerable structural rearrangements upon binding Hsp90 and that the large size of the p23/Sba1p-Hsp90 interaction surface facilitates maintenance of high affinity despite sequence divergence during evolution. The large interface may also contribute to preserving a protective function in an environment in which Hsp90 inhibitory compounds can be produced by various microorganisms.

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  • The difference in in vitro ATPase IC50 is not sufficient alone to explain the cellular-level observation because in vivo Hsp90 ATPase activity is regulated by cochaperones.

    “However, since in vivo ATPase activity of Hsp90 is known to be regulated by many cochaperones which either stimulate or bring down Hsp90 ATPase activity, the difference in ATPase IC50 observed in vitro is not sufficient alone to explain the observation at the cellular level.”

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Authors
Forafonov, F., Toogun, O. A., Grad, I., Suslova, E., Freeman, B. C., & Picard, D.
Affiliations
  • University of Geneva (CH)
  • University of Illinois Urbana-Champaign (US)
Corresponding author
Picard, Didier
Venue
Molecular and Cellular Biology
Published
2008-05-01
Volume
28
Issue
10
Pages
3446-3456
ISSN
  • 0270-7306 (ISSN-L)
  • 1098-5549
OpenAlex
W2041894424
Cited by
84
References
64
Citations by year
2025: 1 · 2024: 1 · 2023: 4 · 2022: 3 · 2021: 1 · 2020: 5 · 2019: 2 · 2018: 1 · 2017: 3 · 2016: 5 · 2015: 2 · 2014: 13 · 2013: 9 · 2012: 6
FWCI
3.71
Type
journal article
Language
en
Open access
Locations
  • Molecular and Cellular Biology (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • Archive ouverte UNIGE (University of Geneva) (publishedVersion)
  • Archive ouverte UNIGE (University of Geneva) (submittedVersion, cc-by)
Funders
  • National Science Foundation
  • Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
  • Fondation Medic
  • National Institutes of Health
  • University of Illinois at Urbana-Champaign
  • National Institute of Diabetes and Digestive and Kidney Diseases (R01DK074270, DK074270)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Heat shock proteins research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Ubiquitin and proteasome pathways
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Fungal and yeast genetics research
Keywords
Hsp90 co-chaperone, Hsp90 inhibitors, chaperone activity, structure-function relationship, protein-protein interfaces, Saccharomyces cerevisiae, sequence divergence
MeSH terms
Prostaglandin-E Synthases, Amino Acid Sequence, Animals, Base Sequence, Cells, Cultured, DNA, Fungal, Genes, Fungal, Genetic Complementation Test, Models, Molecular, Phenotype, Protein Binding, Recombinant Proteins, Saccharomyces cerevisiae, Mutagenesis, Site-Directed, Point Mutation, Sequence Deletion, Sequence Homology, Amino Acid, DNA Primers, Molecular Chaperones, HSP90 Heat-Shock Proteins, Intramolecular Oxidoreductases, Saccharomyces cerevisiae Proteins, Mice

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