The exocyst subunit Sec3 is regulated by a protein quality control pathway
Autor: | Isabelle Jourdain, Rasmus Hartmann-Petersen, Amanda B Abildgaard, Anne-Marie B. Lauridsen, Caroline Kampmeyer, Signe M. Schenstrøm, Antonina Karakostova |
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Jazyk: | angličtina |
Rok vydání: | 2017 |
Předmět: |
0301 basic medicine
Proteasome Endopeptidase Complex Protein subunit Recombinant Fusion Proteins Ubiquitin-Protein Ligases Vesicular Transport Proteins Exocyst Endocytosis Biochemistry Models Biological Exocytosis 03 medical and health sciences Microscopy Electron Transmission Stress Physiological Endopeptidases Schizosaccharomyces HSP70 Heat-Shock Proteins Enzyme Inhibitors Molecular Biology biology Deubiquitinating Enzymes Protein Stability Secretory Vesicles Temperature Ubiquitination Lipid bilayer fusion Cell Biology Cell biology 030104 developmental biology Proteasome Membrane protein Protein Synthesis and Degradation Chaperone (protein) Mutation Proteolysis biology.protein Schizosaccharomyces pombe Proteins Gene Deletion |
Popis: | Exocytosis involves fusion of secretory vesicles with the plasma membrane, thereby delivering membrane proteins to the cell surface and releasing material into the extracellular space. The tethering of the secretory vesicles before membrane fusion is mediated by the exocyst, an essential phylogenetically conserved octameric protein complex. Exocyst biogenesis is regulated by several processes, but the mechanisms by which the exocyst is degraded are unknown. Here, to unravel the components of the exocyst degradation pathway, we screened for extragenic suppressors of a temperature-sensitive fission yeast strain mutated in the exocyst subunit Sec3 (sec3-913). One of the suppressing DNAs encoded a truncated dominant-negative variant of the 26S proteasome subunit, Rpt2, indicating that exocyst degradation is controlled by the ubiquitin-proteasome system. The temperature-dependent growth defect of the sec3-913 strain was gene dosage-dependent and suppressed by blocking the proteasome, Hsp70-type molecular chaperones, the Pib1 E3 ubiquitin-protein ligase, and the deubiquitylating enzyme Ubp3. Moreover, defects in cell septation, exocytosis, and endocytosis in sec3 mutant strains were similarly alleviated by mutation of components in this pathway. We also found that, particularly under stress conditions, wild-type Sec3 degradation is regulated by Pib1 and the 26S proteasome. In conclusion, our results suggest that a cytosolic protein quality control pathway monitors folding and proteasome-dependent turnover of an exocyst subunit and, thereby, controls exocytosis in fission yeast. |
Databáze: | OpenAIRE |
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