Polar subcellular localization of the PIN exporters of the phytohormone auxin is a key determinant of directional, intercellular auxin transport and thus a central topic of both plant cell and developmental biology. Arabidopsis mutants lacking PID, a kinase that phosphorylates PINs, or the MAB4/MEL proteins of unknown molecular function display PIN polarity defects and phenocopy pin mutants, but mechanistic insights into how these factors convey PIN polarity are missing. Here, by combining protein biochemistry with quantitative live-cell imaging, we demonstrate that PINs, MAB4/MELs, and AGC kinases interact in the same complex at the plasma membrane. MAB4/MELs are recruited to the plasma membrane by the PINs and in concert with the AGC kinases maintain PIN polarity through limiting lateral diffusion-based escape of PINs from the polar domain. The PIN-MAB4/MEL-PID protein complex has self-reinforcing properties thanks to positive feedback between AGC kinase-mediated PIN phosphorylation and MAB4/MEL recruitment. We thus uncover the molecular mechanism by which AGC kinases and MAB4/MEL proteins regulate PIN localization and plant development.
We acknowledge Ben Scheres, Christian Luschnig, and Claus Schwechheimer for sharing published material. We thank Monika Hrtyan and Dorota Jaworska at IST Austria and Gerda Lamers and Ward de Winter at IBL Netherlands for technical assistance; Corinna Hartinger, Jakub Hajný, Lesia Rodriguez, Mingyue Li, and Lindy Abas for experimental support; and the Bioimaging Facility at IST Austria and the Bioimaging Core at VIB for imaging support. We are grateful to Christian Luschnig, Lindy Abas, and Roman Pleskot for valuable discussions. We also acknowledge the EMBO for supporting M.G. with a long-term fellowship ( ALTF 1005-2019 ) during the finalization and revision of this manuscript in the laboratory of B.D.R., and we thank R. Pierik for allowing K.V.G. to work on this manuscript during a postdoc in his laboratory at Utrecht University. This work was supported by grants from the European Research Council under the European Union’s Seventh Framework Programme (ERC grant agreements 742985 to J.F., 714055 to B.D.R., and 803048 to M.F.), the Austrian Science Fund (FWF; I 3630-B25 to J.F.), Chemical Sciences (partly) financed by the Dutch Research Council (NWO-CW TOP 700.58.301 to R.O.), the Dutch Research Council (NWO-VICI 865.17.002 to R. Pierik), Grants-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology, Japan (KAKENHI grant 17K17595 to S.N.), the Ministry of Education, Youth and Sports of the Czech Republic (MŠMT project NPUI-LO1417 ), and a China Scholarship Council (to X.W.).
Glanc M, Van Gelderen K, Hörmayer L, et al. AGC kinases and MAB4/MEL proteins maintain PIN polarity by limiting lateral diffusion in plant cells. Current Biology. 2021;31(9):1918-1930. doi:10.1016/j.cub.2021.02.028
Glanc, M., Van Gelderen, K., Hörmayer, L., Tan, S., Naramoto, S., Zhang, X., … Friml, J. (2021). AGC kinases and MAB4/MEL proteins maintain PIN polarity by limiting lateral diffusion in plant cells. Current Biology. Elsevier. https://doi.org/10.1016/j.cub.2021.02.028
Glanc, Matous, K Van Gelderen, Lukas Hörmayer, Shutang Tan, S Naramoto, Xixi Zhang, David Domjan, et al. “AGC Kinases and MAB4/MEL Proteins Maintain PIN Polarity by Limiting Lateral Diffusion in Plant Cells.” Current Biology. Elsevier, 2021. https://doi.org/10.1016/j.cub.2021.02.028.
M. Glanc et al., “AGC kinases and MAB4/MEL proteins maintain PIN polarity by limiting lateral diffusion in plant cells,” Current Biology, vol. 31, no. 9. Elsevier, pp. 1918–1930, 2021.
Glanc M, Van Gelderen K, Hörmayer L, Tan S, Naramoto S, Zhang X, Domjan D, Vcelarova L, Hauschild R, Johnson AJ, de Koning E, van Dop M, Rademacher E, Janson S, Wei X, Molnar G, Fendrych M, De Rybel B, Offringa R, Friml J. 2021. AGC kinases and MAB4/MEL proteins maintain PIN polarity by limiting lateral diffusion in plant cells. Current Biology. 31(9), 1918–1930.
Glanc, Matous, et al. “AGC Kinases and MAB4/MEL Proteins Maintain PIN Polarity by Limiting Lateral Diffusion in Plant Cells.” Current Biology, vol. 31, no. 9, Elsevier, 2021, pp. 1918–30, doi:10.1016/j.cub.2021.02.028.
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