Hsp90 constitutes one of the major chaperone machinery in the cell. The Hsp70 assists Hsp90 in its client maturation though the underlying basis of the Hsp70 role remains to be explored. In the present study, using S. cerevisiae strain expressing Ssa1 as sole Ssa Hsp70, we identified novel mutations in the nucleotide-binding domain of yeast Ssa1 Hsp70 (Ssa1-T175N and Ssa1-D158N) that adversely affect the maturation of Hsp90 clients v-Src and Ste11. The identified Ssa1 amino acids critical for Hsp90 function were also found to be conserved across species such as in E.coli DnaK and the constitutive Hsp70 isoform (HspA8) in humans. These mutations are distal to the C-terminus of Hsp70, that primarily mediates Hsp90 interaction through the bridge protein Sti1, and proximal to Ydj1 (Hsp40 co-chaperone of Hsp70 family) binding region. Intriguingly, we found that the bridge protein Sti1 is critical for cellular viability in cells expressing Ssa1-T175N (A1-T175N) or Ssa1-D158N (A1-D158N) as sole Ssa Hsp70. The growth defect was specific for sti1Δ, as deletion of none of the other Hsp90 co-chaperones showed lethality in A1-T175N or A1-D158N. Mass-spectrometry based whole proteome analysis of A1-T175N cells lacking Sti1 showed an altered abundance of various kinases and transcription factors suggesting compromised Hsp90 activity. Further proteomic analysis showed that pathways involved in signaling, signal transduction, and protein phosphorylation are markedly downregulated in the A1-T175N upon repressing Sti1 expression using doxycycline regulatable promoter. In contrast to Ssa1, the homologous mutations in Ssa4 (Ssa4-T175N/D158N), the stress inducible Hsp70 isoform, supported cell growth even in the absence of Sti1. Overall, our data suggest that Ydj1 competes with Hsp90 for binding to Hsp70, and thus regulates Hsp90 interaction with the nucleotide-binding domain of Hsp70. The study thus provides new insight into the Hsp70-mediated regulation of Hsp90 and broadens our understanding of the intricate complexities of the Hsp70-Hsp90 network.
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http://dx.doi.org/10.1371/journal.pgen.1010442 | DOI Listing |
Nat Commun
January 2025
Department for NMR-based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
The pathological deposition of tau and amyloid-beta into insoluble amyloid fibrils are pathological hallmarks of Alzheimer's disease. Molecular chaperones are important cellular factors contributing to the regulation of tau misfolding and aggregation. Here we reveal an Hsp90-independent mechanism by which the co-chaperone p23 as well as a molecular complex formed by two co-chaperones, p23 and FKBP51, modulates tau aggregation.
View Article and Find Full Text PDFZhongguo Zhong Yao Za Zhi
December 2024
Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences Beijing 100700, China.
This study aimed to investigate the potential role of Colquhounia Root Tablets against bone destruction in rheumatoid arthritis(RA) and its molecular mechanism. The study used ultra-performance liquid chromatography-mass spectrometry to analyze the major components of Colquhounia Root Tablets and predicted its candidate target gene set based on the major components. The key targets of RA bone destruction were obtained through GeneCards and the Database of Genetics and Medical Literature(OMIM), protein-protein interaction(PPI) network was constructed, and the key targets were identified by topological analysis.
View Article and Find Full Text PDFLife Sci
January 2025
Institute of Radiation Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Tianjin 300192, China. Electronic address:
As a common side effect of radiotherapy, radiation-induced intestinal injury (RIII) greatly affects the prognosis of patients and the efficacy of radiotherapy. Current therapeutic strategies for RIII are still very limited. Thus, the identification of effective radioprotective agents is of great importance.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Key Laboratory of Cryogenics Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Laboratory of Controllable Preparation and Application of Nanomaterials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Sublethal tumor cells have an urgent need for energy, making it common for them to switch metabolic phenotypes between glycolysis and oxidative phosphorylation (OXPHOS) for compensatory energy supply; thus, the synchronous interference of dual metabolic pathways for limiting energy level is essential in inhibiting sublethal tumor growth. Herein, a multifunctional nanoplatform of Co-MOF-loaded anethole trithione (ADT) and myristyl alcohol (MA), modified with GOx and hyaluronic acid (HA) was developed, namely, CAMGH. It could synchronously interfere with dual metabolic pathways including glycolysis and OXPHOS to restrict the adenosine triphosphate (ATP) supply, achieving the inhibition to sublethal tumors after microwave (MW) thermal therapy.
View Article and Find Full Text PDFSmall
January 2025
School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, 646000, China.
Covalent organic frameworks (COFs), known for their exceptional in situ encapsulation and precise release capabilities, are emerging as pioneering drug delivery systems. This study introduces a hypoxia-responsive COF designed to encapsulate the chemotherapy drug gambogic acid (GA) in situ. Bimetallic gold-palladium islands were grown on UiO-66-NH (UiO) to form UiO@Au-Pd (UAPi), which were encapsulated with GA through COF membrane formation, resulting in a core-shell structure (UAPiGC).
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