Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria.
Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria.
Nat Plants. 2020 May;6(5):556-569. doi: 10.1038/s41477-020-0648-9. Epub 2020 May 11.
Directional intercellular transport of the phytohormone auxin mediated by PIN-FORMED (PIN) efflux carriers has essential roles in both coordinating patterning processes and integrating multiple external cues by rapidly redirecting auxin fluxes. PIN activity is therefore regulated by multiple internal and external cues, for which the underlying molecular mechanisms are not fully elucidated. Here, we demonstrate that 3'-PHOSPHOINOSITIDE-DEPENDENT PROTEIN KINASE1 (PDK1), which is conserved in plants and mammals, functions as a molecular hub that perceives upstream lipid signalling and modulates downstream substrate activity through phosphorylation. Using genetic analysis, we show that the loss-of-function Arabidopsis pdk1.1 pdk1.2 mutant exhibits a plethora of abnormalities in organogenesis and growth due to defective polar auxin transport. Further cellular and biochemical analyses reveal that PDK1 phosphorylates D6 protein kinase, a well-known upstream activator of PIN proteins. We uncover a lipid-dependent phosphorylation cascade that connects membrane-composition-based cellular signalling with plant growth and patterning by regulating morphogenetic auxin fluxes.
由 PIN 形成（PIN）外排载体介导的植物激素生长素的定向细胞间运输在协调模式形成过程和通过快速重定向生长素通量整合多个外部线索方面具有重要作用。因此，PIN 活性受到多种内部和外部线索的调节，其潜在的分子机制尚未完全阐明。在这里，我们证明了 3'-磷酸肌醇依赖性蛋白激酶 1（PDK1）在植物和哺乳动物中保守，作为一个分子枢纽，通过磷酸化感知上游脂质信号并调节下游底物活性。通过遗传分析，我们表明，由于极性生长素运输缺陷，拟南芥 pdk1.1 pdk1.2 功能丧失突变体在器官发生和生长中表现出多种异常。进一步的细胞和生化分析表明，PDK1 磷酸化 D6 蛋白激酶，D6 蛋白激酶是 PIN 蛋白的一种众所周知的上游激活剂。我们揭示了一种脂质依赖性磷酸化级联反应，通过调节形态发生生长素通量，将基于膜组成的细胞信号与植物生长和模式形成联系起来。
