The AGC kinase, PINOID, blocks interactive ABCB/PIN auxin transport.
Plant growth and development is determined by intracellular and intercellular auxin gradients that are controlled at first hand by auxin efflux catalysts of the ABCB/PGP and PIN families. ABCB transport activity was shown to be counter-actively regulated by protein phosphorylation by the AGC protein kinase, PINOID (PID), that is coordinated by interaction with the immunophilin-like FKBP42, TWISTED DWARF1 (TWD1). In contrast, PID was shown to determine PIN polarity, however, the direct impact of PID on PIN activity has yet not been tested. Co-expression in yeast indicates that PID had no effect on PIN1,2 alone but specifically inhibits interactive ABCB1-PIN1/PIN2 auxin efflux in an action that is dependent on its kinase activity. PIN1-PID co-transfection in N. benthamiana revealed that PID blocks PIN1-mediated auxin efflux without changing PIN1 location. In summary, these data provide evidence that PID phosphorylation does not only determine PIN polarity but also has a direct impact on transport activity of the activity of the binary PIN-ABCB1 complex.
Department of Biology-Plant Biology, University of Fribourg, Fribourg, Switzerland.
Bangjun
B
Wang
Sina
S
Henrichs
Markus
M
Geisler
D001692:Biological Transport / Q000235:genetics / Q000502:physiology; D007210:Indoleacetic Acids / Q000378:metabolism*; D010766:Phosphorylation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000201:enzymology / Q000378:metabolism*
D007210:Indoleacetic Acids; D010940:Plant Proteins