Subcellular homeostasis of phytohormone auxin is mediated by the ER localized PIN5 transporter Journal Article

Author(s): Mravec, Jozef; Skůpa, Petr; Bailly, Aurélien; Hoyerová, Klára; Křeček, Pavel; Bielach, Agnieszka; Petrášek, Jan; Zhang, Jing; Gaykova, Vassilena; Stierhof, York-Dieter; Dobrev, Petre I; Schwarzerová, Kateřina; Rolčík, Jakub; Seifertová, Daniela; Luschnig, Christian; Benková, Eva; Zažímalová, Eva; Geisler, Markus; Friml, Jiří
Article Title: Subcellular homeostasis of phytohormone auxin is mediated by the ER localized PIN5 transporter
Abstract: The plant signalling molecule auxin provides positional informa-tion in a variety of developmental processes by means of its differential distribution (gradients) within plant tissues. Thus, cellular auxin levels often determine the developmental output of auxin signalling. Conceptually, transmembrane transport and metabolic processes regulate the steady-state levels of auxin in any given cell2,3. In particular, PIN auxin-efflux-carrier-mediated, directional transport between cells is crucial for generating auxin gradients2,4,5. Here we show that Arabidopsis thaliana PIN5, an atypical member of the PIN gene family, encodes a functional auxin transporter that is required for auxin-mediated develop-ment. PIN5 does not have a direct role in cell-to-cell transport but regulates intracellular auxin homeostasis and metabolism. PIN5 localizes, unlike other characterized plasma membrane PIN proteins, to endoplasmic reticulum (ER), presumably medi-ating auxin flow from the cytosol to the lumen of the ER. The ER localization of other PIN5-like transporters (including the moss PIN) indicates that the diversification of PIN protein functions in mediating auxin homeostasis at the ER, and cell-to-cell auxin transport at the plasma membrane, represent an ancient event during the evolution of land plants.
Keywords: Cells, Cultured; Mutation; Phylogeny; Phenotype; Homeostasis; Arabidopsis; Arabidopsis Proteins; Indoleacetic Acids; Endoplasmic Reticulum; Membrane Transport Proteins; Plant Growth Regulators; Gene Knockout Techniques
Journal Title: Nature
Volume: 459
Issue 7250
ISSN: 0028-0836
Publisher: Nature Publishing Group  
Date Published: 2009-06-25
Start Page: 1136
End Page: 1140
DOI: 10.1038/nature08066
Open access: no