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bioRxiv · 10.1101/305854

The holdase function of Escherichia coli Hsp70 (DnaK) chaperone

Winardhi, R. S.·Tang, Q.·You, H.·Sheetz, M.·Yan, J.
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Abstract

In Escherichia coli, the DnaK/DnaJ/GrpE system plays a critical role in mediating protein refolding and buffering against protein aggregation due to environmental stress. The underlying mechanism remains unclear. In this work, we probe the activity of DnaK/DnaJ/GrpE system with single-molecule protein refolding assay using tandem repeats of titin immunoglobulin 27 (I27)8. We provide direct evidence that DnaK in apo- and ADP-bound state is predominantly a holdase, which kinetically stabilizes the polyprotein in its unfolded form. Binding of ATP relieves DnaKs holding, allowing protein refolding. The presence of co-chaperone DnaJ and GrpE modulates this holding-release switching, possibly by altering DnaKs nucleotide state. Our findings thus provide important insights to the molecular mechanism of DnaK/DnaJ/GrpE system.

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Winardhi, R. S., Tang, Q., You, H., Sheetz, M., Yan, J.. 2018-04-21. The holdase function of Escherichia coli Hsp70 (DnaK) chaperone. https://doi.org/10.1101/305854

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