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Spécificités fonctionnelles des Hsp70 cytoplasmiques chez la levure

Abstract : Hsp70 are a highly conserved family of ubiquitous molecular chaperones that play essential roles in protein folding, transport or degradation. The cytosol of most eukaryotic cells contains multiple highly conserved Hsp70 orthologs that differ mainly by their spatio-temporal expression patterns. While several reports suggest that specialized functions of Hsp70 orthologs were selected through evolution, few studies addressed systematically this issue. First, we compared the ability of Ssa1-Ssa4 from Saccharomyces cerevisiae and Ssa5-Ssa8 from the evolutionary distant yeast Yarrowia lipolytica to perform Hsp70-dependent tasks when expressed as the sole Hsp70 for S. cerevisiae in vivo. We showed that Hsp70 isoforms: 1) supported yeast viability yet with markedly different growth rates; 2) influenced the propagation and stability of the [PSI+] and [URE3] prions; but 3) did not significantly affect the proteasomal degradation rate of CFTR. Second, we showed that biofilm formation in yeast depends on the Hsp70 machinery that controls, through distinct pathways, the expression, maturation and recycling of a cell-surface adhesin (Flo11) required for this process. Finally, we constructed and analyzed Y. lipolytica mutants bearing one or multiple deletion(s) in genes encoding molecular chaperones and others proteostasis modulators (e.g. Hsp70, Hsp104, CHIP). Despite very high homology and overlapping functions, the different Hsp70 orthologs have evolved to possess distinct activities that are required to cope with different types of substrates or stress situations.
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Submitted on : Friday, August 26, 2011 - 10:46:38 AM
Last modification on : Friday, August 5, 2022 - 2:38:10 PM
Long-term archiving on: : Sunday, December 4, 2016 - 3:39:15 PM


  • HAL Id : pastel-00617115, version 1
  • PRODINRA : 246171


Céline Martineau. Spécificités fonctionnelles des Hsp70 cytoplasmiques chez la levure. Biochimie, Biologie Moléculaire. AgroParisTech, 2010. Français. ⟨NNT : 2010AGPT0012⟩. ⟨pastel-00617115⟩



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