title: Artificial ubiquitylation is sufficient for sorting of a plasma membrane ATPase to the vacuolar lumen of Arabidopsis cells.
abstract: Sorting of transmembrane proteins into the inner vesicles of multivesicular bodies for subsequent delivery to the vacuole/lysosome can be induced by attachment of a single ubiquitin or K63-linked ubiquitin chains to the cytosolic portion of the cargo in yeast and mammals. In plants, large efforts have been undertaken to elucidate the mechanisms of vacuolar trafficking of soluble proteins. Sorting of transmembrane proteins, by contrast, is still largely unexplored. As a proof of principle, that ubiquitin is involved in vacuolar sorting in plants we show that a translational fusion of a single ubiquitin to the Arabidopsis plasma membrane ATPase PMA-EGFP is sufficient to induce its endocytosis and sorting into the vacuolar lumen. Sorting of the artificial reporter is not dependent on ubiquitin chain formation, but involves ubiquitin's hydrophobic patch and can be inhibited by coexpression of a dominant-negative version of the ESCRT (endosomal sorting complex required for transport) related protein AtSKD1 (SUPPRESSOR OF K+ TRANSPORT GROWTH DEFECT1). Our results suggest that ubiquitin can in principle act as vacuolar sorting signal in plants.
authors.affiliation: Botanical Institute III, Biocenter, University of Cologne, Zülpicher Str. 47b, 50674, Cologne, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Herberth
authors.forename: Mojgan
authors.initials: M
authors.lastname: Shahriari
authors.forename: Michael
authors.initials: M
authors.lastname: Bruderek
authors.forename: Florian
authors.initials: F
authors.lastname: Hessner
authors.forename: Britta
authors.initials: B
authors.lastname: Müller
authors.forename: Martin
authors.initials: M
authors.lastname: Hülskamp
authors.forename: Swen
authors.initials: S
authors.lastname: Schellmann
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D017360:Arabidopsis / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology*; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology*; D015398:Signal Transduction; D025801:Ubiquitin / Q000378:metabolism*; D057149:Ubiquitinated Proteins / Q000378:metabolism*; D054875:Ubiquitination; D014617:Vacuoles / Q000502:physiology*
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D025801:Ubiquitin; D057149:Ubiquitinated Proteins; D000251:Adenosine Triphosphatases