Microautophagy of the nucleus coincides with a vacuolar diffusion barrier at nuclear-vacuolar junctions.

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Serval ID
serval:BIB_25EA5A83466C
Type
Article: article from journal or magazin.
Collection
Publications
Title
Microautophagy of the nucleus coincides with a vacuolar diffusion barrier at nuclear-vacuolar junctions.
Journal
Molecular Biology of the Cell
Author(s)
Dawaliby R., Mayer A.
ISSN
1939-4586 (Electronic)
ISSN-L
1059-1524
Publication state
Published
Issued date
2010
Volume
21
Number
23
Pages
4173-4183
Language
english
Abstract
Nuclei bind yeast vacuoles via nucleus-vacuole (NV) junctions. Under nutrient restriction, NV junctions invaginate and release vesicles filled with nuclear material into vacuoles, resulting in piecemeal microautophagy of the nucleus (PMN). We show that the electrochemical gradient across the vacuolar membrane promotes invagination of NV junctions. Existing invaginations persist independently of the gradient, but final release of PMN vesicles requires again V-ATPase activity. We find that NV junctions form a diffusion barrier on the vacuolar membrane that excludes V-ATPase but is enriched in the VTC complex and accessible to other membrane-integral proteins. V-ATPase exclusion depends on the NV junction proteins Nvj1p,Vac8p, and the electrochemical gradient. It also depends on factors of lipid metabolism, such as the oxysterol binding protein Osh1p and the enoyl-CoA reductase Tsc13p, which are enriched in NV junctions, and on Lag1p and Fen1p. Our observations suggest that NV junctions form in two separable steps: Nvj1p and Vac8p suffice to establish contact between the two membranes. The electrochemical potential and lipid-modifying enzymes are needed to establish the vacuolar diffusion barrier, invaginate NV junctions, and form PMN vesicles.
Keywords
Autophagy, Carrier Proteins/metabolism, Cell Nucleus/physiology, Cell Nucleus/ultrastructure, Cytoplasmic Vesicles/metabolism, Diffusion, Flap Endonucleases/metabolism, Intracellular Membranes/physiology, Intracellular Membranes/ultrastructure, Membrane Proteins/metabolism, Oxidoreductases Acting on CH-CH Group Donors/metabolism, Proton-Motive Force, Receptors, Cytoplasmic and Nuclear/metabolism, Saccharomyces cerevisiae Proteins/metabolism, Vacuolar Proton-Translocating ATPases/metabolism, Vacuoles/physiology, Vacuoles/ultrastructure, Vesicular Transport Proteins/metabolism, Yeasts
Pubmed
Web of science
Create date
27/01/2012 11:24
Last modification date
03/03/2018 15:05
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