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Updated: May 17, 2026

In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells
Published on: September 2, 2019
The DNAJA2 substrate release mechanism is essential for chaperone-mediated folding
Imad Baaklini1, Michael J H Wong, Christine Hantouche
1Department of Biochemistry, McGill University and Groupe de Recherche Axé sur la Structure des Protéines, Montreal, Quebec H3G 0B1, Canada.
DNAJA1 and DNAJA2 are crucial co-chaperones for Hsp70/Hsc70. Specific domains within DNAJA2 are essential for substrate release and cellular functions, highlighting distinct mechanisms in protein folding.
Area of Science:
- Molecular Biology
- Protein Folding
- Chaperone Proteins
Background:
- DNAJA1 and DNAJA2 are key J domain partners of Hsp70/Hsc70 chaperones.
- While similar to yeast/bacterial co-chaperones, their specific functions are not well understood.
Purpose of the Study:
- To investigate the distinct functional mechanisms of DNAJA1 and DNAJA2.
- To identify specific domains responsible for DNAJA2's cellular activities and substrate release.
Main Methods:
- Utilized purified proteins and site-directed mutagenesis to study DNAJA1 and DNAJA2 mutants.
- Assessed substrate binding and release during Hsc70 transfer.
- Limited proteolysis to analyze conformational differences.
Main Results:
- DNAJA2 exhibits specific activities in luciferase folding and HERG trafficking.
- A mutation (DJA2-Δm2) impaired substrate release, an effect mirrored in DNAJA1.
- Substrate release requires the J domain and Hsc70 ATP hydrolysis, with differing nucleotide dependence between DNAJA1 and DNAJA2.
Conclusions:
- Specific domains within DNAJA proteins are critical for their function as co-chaperones.
- DNAJA1 and DNAJA2 possess distinct mechanisms for substrate release and cellular roles.
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