title: Multivesicular bodies mature from the trans-Golgi network/early endosome in Arabidopsis.
abstract: The plant trans-Golgi network/early endosome (TGN/EE) is a major hub for secretory and endocytic trafficking with complex molecular mechanisms controlling sorting and transport of cargo. Vacuolar transport from the TGN/EE to multivesicular bodies/late endosomes (MVBs/LEs) is assumed to occur via clathrin-coated vesicles, although direct proof for their participation is missing. Here, we present evidence that post-TGN transport toward lytic vacuoles occurs independently of clathrin and that MVBs/LEs are derived from the TGN/EE through maturation. We show that the V-ATPase inhibitor concanamycin A significantly reduces the number of MVBs and causes TGN and MVB markers to colocalize in Arabidopsis thaliana roots. Ultrastructural analysis reveals the formation of MVBs from the TGN/EE and their fusion with the vacuole. The localization of the ESCRT components VPS28, VPS22, and VPS2 at the TGN/EE and MVBs/LEs indicates that the formation of intraluminal vesicles starts already at the TGN/EE. Accordingly, a dominant-negative mutant of VPS2 causes TGN and MVB markers to colocalize and blocks vacuolar transport. RNA interference-mediated knockdown of the annexin ANNAT3 also yields the same phenotype. Together, these data indicate that MVBs originate from the TGN/EE in a process that requires the action of ESCRT for the formation of intraluminal vesicles and annexins for the final step of releasing MVBs as a transport carrier to the vacuole.
authors.affiliation: Plant Cell Biology, Centre for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Scheuring
authors.forename: Corrado
authors.initials: C
authors.lastname: Viotti
authors.forename: Falco
authors.initials: F
authors.lastname: Krüger
authors.forename: Fabian
authors.initials: F
authors.lastname: Künzl
authors.forename: Silke
authors.initials: S
authors.lastname: Sturm
authors.forename: Julia
authors.initials: J
authors.lastname: Bubeck
authors.forename: Stefan
authors.initials: S
authors.lastname: Hillmer
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Frigerio
authors.forename: David G
authors.initials: DG
authors.lastname: Robinson
authors.forename: Peter
authors.initials: P
authors.lastname: Pimpl
authors.forename: Karin
authors.initials: K
authors.lastname: Schumacher
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D022163:Clathrin-Coated Vesicles / Q000378:metabolism; D004705:Endocytosis; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism*; D057146:Multivesicular Bodies / Q000378:metabolism* / Q000648:ultrastructure; D018517:Plant Roots / Q000378:metabolism; D021381:Protein Transport; D014617:Vacuoles / Q000378:metabolism / Q000648:ultrastructure; D021601:trans-Golgi Network / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport