title: Overexpression of FAB1A-GFP recruits SNX2b on the endosome membrane in snx1-1 mutant in Arabidopsis.
abstract: Phosphatidylinositol 3,5-bisphosphate [PI(3,5)P2] is one of the phosphoinositides that controls endosomal trafficking events in eukaryotes. PtdIns(3,5)P2 is produced from PI(3)P by phosphatidylinositol 3-phosphate 5-kinase FAB1/PIKfyve. Recently, we reported that FAB1 predominantly localizes on the SNX1-residing late endosomes and a loss-of FAB1 function causes the release of late endosomal effector proteins, ARA7/RABF2b and SORTING NEXIN 1 from the endosome membrane, indicating that FAB1 or its product PtdIns(3,5)P2 mediates the maturation process of the late endosomes. Intriguingly, the ectopic expression of FAB1A could complement the sucrose-dependent seedling growth phenotype of snx1-1 mutant. Here, we demonstrated that the depletion of SNX1 causes the release of SNX2b-mRFP from the endosomal membrane. However, overexpression of FAB1A-GFP reassembles SNX2b-mRFP on the endosomal membrane despite the absence of SNX1. From these results, we proposed that SNX2b homodimer or SNX2a/SNX2b heterodimer might function as functional Sorting Nexin complex instead of SNX1 to attach the endosomal membrane by binding of overproduced PI(3,5)P2 in Arabidopsis.
authors.affiliation: a Laboratory of Cellular Dynamics; Graduate School of Life and Environmental Sciences; Kyoto Prefectural University ; Kyoto , Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Hirano
authors.affiliation: a Laboratory of Cellular Dynamics; Graduate School of Life and Environmental Sciences; Kyoto Prefectural University ; Kyoto , Japan.
authors.forename: Masa H
authors.initials: MH
authors.lastname: Sato
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation / Q000235:genetics*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D058305:Sorting Nexins / Q000235:genetics*
chemical_list: D029681:Arabidopsis Proteins; D011993:Recombinant Fusion Proteins; C584750:SNX1 protein, Arabidopsis; C546322:SNX2b protein, Arabidopsis; D058305:Sorting Nexins; D049452:Green Fluorescent Proteins; C547216:FAB1A protein, Arabidopsis; D017853:Phosphotransferases (Alcohol Group Acceptor)
keywords: 5 bisphosphate; Arabidopsis; FAB1; FAB1/PIKfyve mediates endosome maturation to establish endosome-cortical microtubule interaction in Arabidopsis; Phosphatidylinositol 3-phosphate 5-kinase; Sorting Nexin; endosomes; phosphatydilinositol 3