ESCRTIII-associated protein AtALIX mediates high affinity phosphate transporter trafficking to maintain phosphate homeostasis in Arabidopsis

ABSTRACT: Prior to the release of their cargoes into the vacuolar lumen, sorting endosomes mature into multivesicular bodies (MVB) through the action of ENDOSOMAL COMPLEX REQUIRED FOR TRANSPORT (ESCRT) protein complexes. MVB-mediated sorting of high affinity phosphate transporters (PHT1) to the vacuole limits their plasma membrane levels under phosphate sufficient conditions, a process that allows plants to maintain phosphate homeostasis. We describe here AtALIX, a cytosolic protein that associates to MVB by interacting with ESCRT-III subunit SNF7 and enables PHT1;1 trafficking to the vacuole. Thus, we show that the partial loss of function mutant Atalix-1 displays reduced vacuolar degradation of PHT1;1. AtALIX versions containing the Atalix-1 mutation showed reduced interaction with SNF7, providing a simple molecular explanation for impaired cargo trafficking in Atalix-1 mutants. Indeed, Atalix-1 mutation also hampered vacuolar sorting of brassinosteroid receptor BRI1. In line with a presumed broad target spectrum, Atalix-1 mutation is pleiotropic, provoking reduced plant growth, late flowering and altered vacuole morphogenesis, whereas null mutants are lethal, indicating that AtALIX controls diverse processes in plants being essential for their life.

INSTRUMENT(S): 4800 Proteomics Analyzer

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

SUBMITTER: J. Alberto Medina-Aunon  

LAB HEAD: Vicente Rubio Muñoz

PROVIDER: PXD002075 | Pride | 2015-09-09

REPOSITORIES: pride