Nitrogen Starvation and Stationary Phase Lipophagy Have Distinct Molecular Mechanisms
In yeast, the selective autophagy of intracellular lipid droplets (LDs) or lipophagy can be induced by either nitrogen (N) starvation or carbon limitation (e.g., in the stationary (S) phase). We developed the yeast, <i>Komagataella phaffii</i> (formerly <i>Pichia pastoris</i>...
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| Format: | Article |
| Language: | English |
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MDPI AG
2020-11-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/21/23/9094 |
| _version_ | 1797546235729543168 |
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| author | Ravinder Kumar Muhammad Arifur Rahman Taras Y. Nazarko |
| author_facet | Ravinder Kumar Muhammad Arifur Rahman Taras Y. Nazarko |
| author_sort | Ravinder Kumar |
| collection | DOAJ |
| description | In yeast, the selective autophagy of intracellular lipid droplets (LDs) or lipophagy can be induced by either nitrogen (N) starvation or carbon limitation (e.g., in the stationary (S) phase). We developed the yeast, <i>Komagataella phaffii</i> (formerly <i>Pichia pastoris</i>), as a new lipophagy model and compared the N-starvation and S-phase lipophagy in over 30 autophagy-related mutants using the Erg6-GFP processing assay. Surprisingly, two lipophagy pathways had hardly overlapping stringent molecular requirements. While the N-starvation lipophagy strictly depended on the core autophagic machinery (Atg1-Atg9, Atg18, and Vps15), vacuole fusion machinery (Vam7 and Ypt7), and vacuolar proteolysis (proteinases A and B), only Atg6 and proteinases A and B were essential for the S-phase lipophagy. The rest of the proteins were only partially required in the S-phase. Moreover, we isolated the <i>prl1</i> (for the positive regulator of lipophagy 1) mutant affected in the S-phase lipophagy, but not N-starvation lipophagy. The <i>prl1</i> defect was at a stage of delivery of the LDs from the cytoplasm to the vacuole, further supporting the mechanistically different nature of the two lipophagy pathways. Taken together, our results suggest that N-starvation and S-phase lipophagy have distinct molecular mechanisms. |
| first_indexed | 2024-03-10T14:27:14Z |
| format | Article |
| id | doaj.art-7da682026fc949d38295329522e5b60a |
| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-10T14:27:14Z |
| publishDate | 2020-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | International Journal of Molecular Sciences |
| spelling | doaj.art-7da682026fc949d38295329522e5b60a2023-11-20T22:53:28ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672020-11-012123909410.3390/ijms21239094Nitrogen Starvation and Stationary Phase Lipophagy Have Distinct Molecular MechanismsRavinder Kumar0Muhammad Arifur Rahman1Taras Y. Nazarko2Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USADepartment of Biology, Georgia State University, Atlanta, GA 30303, USASection of Molecular Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USAIn yeast, the selective autophagy of intracellular lipid droplets (LDs) or lipophagy can be induced by either nitrogen (N) starvation or carbon limitation (e.g., in the stationary (S) phase). We developed the yeast, <i>Komagataella phaffii</i> (formerly <i>Pichia pastoris</i>), as a new lipophagy model and compared the N-starvation and S-phase lipophagy in over 30 autophagy-related mutants using the Erg6-GFP processing assay. Surprisingly, two lipophagy pathways had hardly overlapping stringent molecular requirements. While the N-starvation lipophagy strictly depended on the core autophagic machinery (Atg1-Atg9, Atg18, and Vps15), vacuole fusion machinery (Vam7 and Ypt7), and vacuolar proteolysis (proteinases A and B), only Atg6 and proteinases A and B were essential for the S-phase lipophagy. The rest of the proteins were only partially required in the S-phase. Moreover, we isolated the <i>prl1</i> (for the positive regulator of lipophagy 1) mutant affected in the S-phase lipophagy, but not N-starvation lipophagy. The <i>prl1</i> defect was at a stage of delivery of the LDs from the cytoplasm to the vacuole, further supporting the mechanistically different nature of the two lipophagy pathways. Taken together, our results suggest that N-starvation and S-phase lipophagy have distinct molecular mechanisms.https://www.mdpi.com/1422-0067/21/23/9094autophagic machineryautophagy<i>Komagataella phaffii</i>lipid dropletslipophagy<i>Pichia pastoris</i> |
| spellingShingle | Ravinder Kumar Muhammad Arifur Rahman Taras Y. Nazarko Nitrogen Starvation and Stationary Phase Lipophagy Have Distinct Molecular Mechanisms International Journal of Molecular Sciences autophagic machinery autophagy <i>Komagataella phaffii</i> lipid droplets lipophagy <i>Pichia pastoris</i> |
| title | Nitrogen Starvation and Stationary Phase Lipophagy Have Distinct Molecular Mechanisms |
| title_full | Nitrogen Starvation and Stationary Phase Lipophagy Have Distinct Molecular Mechanisms |
| title_fullStr | Nitrogen Starvation and Stationary Phase Lipophagy Have Distinct Molecular Mechanisms |
| title_full_unstemmed | Nitrogen Starvation and Stationary Phase Lipophagy Have Distinct Molecular Mechanisms |
| title_short | Nitrogen Starvation and Stationary Phase Lipophagy Have Distinct Molecular Mechanisms |
| title_sort | nitrogen starvation and stationary phase lipophagy have distinct molecular mechanisms |
| topic | autophagic machinery autophagy <i>Komagataella phaffii</i> lipid droplets lipophagy <i>Pichia pastoris</i> |
| url | https://www.mdpi.com/1422-0067/21/23/9094 |
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