Vac8 Controls Vacuolar Membrane Dynamics during Different Autophagy Pathways in <i>Saccharomyces cerevisiae</i>

The yeast vacuole is a vital organelle, which is required for the degradation of aberrant intracellular or extracellular substrates and the recycling of the resulting nutrients as newly available building blocks for the cellular metabolism. Like the plant vacuole or the mammalian lysosome, the yeast...

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Main Authors: Fahd Boutouja, Christian M. Stiehm, Christina Reidick, Thomas Mastalski, Rebecca Brinkmeier, Fouzi El Magraoui, Harald W. Platta
Format: Article
Language:English
Published: MDPI AG 2019-06-01
Series:Cells
Subjects:
Online Access:https://www.mdpi.com/2073-4409/8/7/661
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author Fahd Boutouja
Christian M. Stiehm
Christina Reidick
Thomas Mastalski
Rebecca Brinkmeier
Fouzi El Magraoui
Harald W. Platta
author_facet Fahd Boutouja
Christian M. Stiehm
Christina Reidick
Thomas Mastalski
Rebecca Brinkmeier
Fouzi El Magraoui
Harald W. Platta
author_sort Fahd Boutouja
collection DOAJ
description The yeast vacuole is a vital organelle, which is required for the degradation of aberrant intracellular or extracellular substrates and the recycling of the resulting nutrients as newly available building blocks for the cellular metabolism. Like the plant vacuole or the mammalian lysosome, the yeast vacuole is the destination of biosynthetic trafficking pathways that transport the vacuolar enzymes required for its functions. Moreover, substrates destined for degradation, like extracellular endocytosed cargoes that are transported by endosomes/multivesicular bodies as well as intracellular substrates that are transported via different forms of autophagosomes, have the vacuole as destination. We found that non-selective bulk autophagy of cytosolic proteins as well as the selective autophagic degradation of peroxisomes (pexophagy) and ribosomes (ribophagy) was dependent on the armadillo repeat protein Vac8 in <i>Saccharomyces cerevisiae</i>. Moreover, we showed that pexophagy and ribophagy depended on the palmitoylation of Vac8. In contrast, we described that Vac8 was not involved in the acidification of the vacuole nor in the targeting and maturation of certain biosynthetic cargoes, like the aspartyl-protease Pep4 (PrA) and the carboxy-peptidase Y (CPY), indicating a role of Vac8 in the uptake of selected cargoes. In addition, we found that the hallmark phenotype of the <i>vac8</i>&#916; strain, namely the characteristic appearance of fragmented and clustered vacuoles, depended on the growth conditions. This fusion defect observed in standard glucose medium can be complemented by the replacement with oleic acid or glycerol medium. This complementation of vacuolar morphology also partially restores the degradation of peroxisomes. In summary, we found that Vac8 controlled vacuolar morphology and activity in a context- and cargo-dependent manner.
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spelling doaj.art-1ce3c3badd664b57b476fffeb64b058c2023-09-03T00:32:10ZengMDPI AGCells2073-44092019-06-018766110.3390/cells8070661cells8070661Vac8 Controls Vacuolar Membrane Dynamics during Different Autophagy Pathways in <i>Saccharomyces cerevisiae</i>Fahd Boutouja0Christian M. Stiehm1Christina Reidick2Thomas Mastalski3Rebecca Brinkmeier4Fouzi El Magraoui5Harald W. Platta6Biochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44780 Bochum, GermanyBiochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44780 Bochum, GermanyBiochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44780 Bochum, GermanyBiochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44780 Bochum, GermanyBiochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44780 Bochum, GermanyBiomedizinische Forschung, Leibniz-Institute for Analytical Sciences (ISAS e.V.), 44139 Dortmund, GermanyBiochemie Intrazellulärer Transportprozesse, Ruhr-Universität Bochum, 44780 Bochum, GermanyThe yeast vacuole is a vital organelle, which is required for the degradation of aberrant intracellular or extracellular substrates and the recycling of the resulting nutrients as newly available building blocks for the cellular metabolism. Like the plant vacuole or the mammalian lysosome, the yeast vacuole is the destination of biosynthetic trafficking pathways that transport the vacuolar enzymes required for its functions. Moreover, substrates destined for degradation, like extracellular endocytosed cargoes that are transported by endosomes/multivesicular bodies as well as intracellular substrates that are transported via different forms of autophagosomes, have the vacuole as destination. We found that non-selective bulk autophagy of cytosolic proteins as well as the selective autophagic degradation of peroxisomes (pexophagy) and ribosomes (ribophagy) was dependent on the armadillo repeat protein Vac8 in <i>Saccharomyces cerevisiae</i>. Moreover, we showed that pexophagy and ribophagy depended on the palmitoylation of Vac8. In contrast, we described that Vac8 was not involved in the acidification of the vacuole nor in the targeting and maturation of certain biosynthetic cargoes, like the aspartyl-protease Pep4 (PrA) and the carboxy-peptidase Y (CPY), indicating a role of Vac8 in the uptake of selected cargoes. In addition, we found that the hallmark phenotype of the <i>vac8</i>&#916; strain, namely the characteristic appearance of fragmented and clustered vacuoles, depended on the growth conditions. This fusion defect observed in standard glucose medium can be complemented by the replacement with oleic acid or glycerol medium. This complementation of vacuolar morphology also partially restores the degradation of peroxisomes. In summary, we found that Vac8 controlled vacuolar morphology and activity in a context- and cargo-dependent manner.https://www.mdpi.com/2073-4409/8/7/661autophagypexophagyribophagybulk autophagyvacuoleVac8
spellingShingle Fahd Boutouja
Christian M. Stiehm
Christina Reidick
Thomas Mastalski
Rebecca Brinkmeier
Fouzi El Magraoui
Harald W. Platta
Vac8 Controls Vacuolar Membrane Dynamics during Different Autophagy Pathways in <i>Saccharomyces cerevisiae</i>
Cells
autophagy
pexophagy
ribophagy
bulk autophagy
vacuole
Vac8
title Vac8 Controls Vacuolar Membrane Dynamics during Different Autophagy Pathways in <i>Saccharomyces cerevisiae</i>
title_full Vac8 Controls Vacuolar Membrane Dynamics during Different Autophagy Pathways in <i>Saccharomyces cerevisiae</i>
title_fullStr Vac8 Controls Vacuolar Membrane Dynamics during Different Autophagy Pathways in <i>Saccharomyces cerevisiae</i>
title_full_unstemmed Vac8 Controls Vacuolar Membrane Dynamics during Different Autophagy Pathways in <i>Saccharomyces cerevisiae</i>
title_short Vac8 Controls Vacuolar Membrane Dynamics during Different Autophagy Pathways in <i>Saccharomyces cerevisiae</i>
title_sort vac8 controls vacuolar membrane dynamics during different autophagy pathways in i saccharomyces cerevisiae i
topic autophagy
pexophagy
ribophagy
bulk autophagy
vacuole
Vac8
url https://www.mdpi.com/2073-4409/8/7/661
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