Subcellular homeostasis of phytohormone auxin is mediated by the ER-localized PIN5 transporter.
The plant signalling molecule auxin provides positional information 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 cell. In particular, PIN auxin-efflux-carrier-mediated, directional transport between cells is crucial for generating auxin gradients. 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 development. 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 mediating 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.
Mravec
Jozef
J
Department of Plant Systems Biology, VIB and Department of Plant Biotechnology and Genetics, Ghent University, 9052 Gent, Belgium.
Skůpa
Petr
P
Bailly
Aurélien
A
Hoyerová
Klára
K
Krecek
Pavel
P
Bielach
Agnieszka
A
Petrásek
Jan
J
Zhang
Jing
J
Gaykova
Vassilena
V
Stierhof
York-Dieter
YD
Dobrev
Petre I
PI
Schwarzerová
Katerina
K
Rolcík
Jakub
J
Seifertová
Daniela
D
Luschnig
Christian
C
Benková
Eva
E
Zazímalová
Eva
E
Geisler
Markus
M
Friml
Jirí
J
D017360:Arabidopsis / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D055786:Gene Knockout Techniques; D006706:Homeostasis / Q000502:physiology*; D007210:Indoleacetic Acids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000378:metabolism
D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D026901:Membrane Transport Proteins; C541719:PIN-FORMED 5 protein, Arabidopsis; D010937:Plant Growth Regulators