AtSNX1 defines an endosome for auxin-carrier trafficking in Arabidopsis.
Jaillais, Yvon 1; Fobis-Loisy, Isabelle 1; Miege, Christine 1; Rollin, Claire 1; Gaude, Thierry 1
[Letter]
Nature.
443(7107):106-109, September 7, 2006.
(Format: HTML, PDF)
Polarized cellular distribution of the phytohormone auxin and its carriers is essential for normal plant growth and development. Polar auxin transport 1,2 is maintained by a network of auxin influx (AUX) 3 and efflux (PIN) 1,2,4-6 carriers. Both auxin transport and PIN protein cycling between the plasma membrane and endosomes require the activity of the endosomal GNOM 1,2,7,8; however, intracellular routes taken by these carriers remain largely unknown. Here we show that Arabidopsis thaliana SORTING NEXIN 1 (AtSNX1) is involved in the auxin pathway and that PIN2, but not PIN1 or AUX1, is transported through AtSNX1-containing endosomes. We demonstrate that the snx1-null mutant exhibits multiple auxin-related defects and that loss of function of AtSNX1 severely enhances the phenotype of a weak gnom mutant. In root cells, we further show that AtSNX1 localizes to an endosomal compartment distinct from GNOM-containing endosomes, and that PIN2 accumulates in this compartment after treatment with the phosphatidylinositol-3-OH kinase inhibitor wortmannin or after a gravity stimulus. Our data reveal the existence of a novel endosomal compartment involved in PIN2 endocytic sorting and plant development.
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