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Free keywords:
Cell Survival/genetics
Escherichia coli/genetics/*metabolism
Escherichia coli Proteins/genetics/isolation & purification/*metabolism
HSP70 Heat-Shock Proteins/genetics/*metabolism
Heat-Shock Proteins/genetics/isolation & purification/*metabolism
Heat-Shock Response/*genetics
*Molecular Chaperones/genetics/metabolism
Molecular Motor Proteins
Molecular Sequence Data
Multiprotein Complexes/genetics/metabolism
Protein Engineering
*Protein Folding
Protein Transport/physiology
Sequence Homology, Amino Acid
Sequence Homology, Nucleic Acid
Abstract:
Cell survival under severe thermal stress requires the activity of the ClpB (Hsp104) AAA+ chaperone that solubilizes and reactivates aggregated proteins in concert with the DnaK (Hsp70) chaperone system. How protein disaggregation is achieved and whether survival is solely dependent on ClpB-mediated elimination of aggregates or also on reactivation of aggregated proteins has been unclear. We engineered a ClpB variant, BAP, which associates with the ClpP peptidase and thereby is converted into a degrading disaggregase. BAP translocates substrates through its central pore directly into ClpP for degradation. ClpB-dependent translocation is demonstrated to be an integral part of the disaggregation mechanism. Protein disaggregation by the BAP/ClpP complex remains dependent on DnaK, defining a role for DnaK at early stages of the disaggregation reaction. The activity switch of BAP to a degrading disaggregase does not support thermotolerance development, demonstrating that cell survival during severe thermal stress requires reactivation of aggregated proteins.
