Thermotolerance requires refolding of aggregated proteins by substrate translocation through the central pore of ClpB |
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Authors: | Weibezahn Jimena Tessarz Peter Schlieker Christian Zahn Regina Maglica Zeljka Lee Sukyeong Zentgraf Hanswalter Weber-Ban Eilika U Dougan David A Tsai Francis T F Mogk Axel Bukau Bernd |
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Institution: | Zentrum für Molekulare Biologie der Universit?t Heidelberg, Universit?t Heidelberg, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany. |
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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. |
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