Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium.
Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium.
Plant Cell. 2023 Sep 1;35(9):3504-3521. doi: 10.1093/plcell/koad141.
ADAPTOR-ASSOCIATED PROTEIN KINASE1 (AAK1) is a known regulator of clathrin-mediated endocytosis in mammals. Human AAK1 phosphorylates the μ2 subunit of the ADAPTOR PROTEIN-2 (AP-2) complex (AP2M) and plays important roles in cell differentiation and development. Previous interactome studies discovered the association of AAK1 with AP-2 in Arabidopsis (Arabidopsis thaliana), but its function was unclear. Here, genetic analysis revealed that the Arabidopsis aak1 and ap2m mutants both displayed altered root tropic growth, including impaired touch- and gravity-sensing responses. In Arabidopsis, AAK1-phosphorylated AP2M on Thr-163, and expression of the phospho-null version of AP2M in the ap2m mutant led to an aak1-like phenotype, whereas the phospho-mimic forms of AP2M rescued the aak1 mutant. In addition, we found that the AAK1-dependent phosphorylation state of AP2M modulates the frequency distribution of endocytosis. Our data indicate that the phosphorylation of AP2M on Thr-163 by AAK1 fine-tunes endocytosis in the Arabidopsis root to control its tropic growth.
衔接蛋白相关激酶 1（AAK1）是一种已知的调节哺乳动物网格蛋白介导的胞吞作用的蛋白激酶。人类 AAK1 可磷酸化衔接蛋白 2（AP-2）复合物（AP2M）的 μ2 亚基，并在细胞分化和发育中发挥重要作用。先前的相互作用组研究发现 AAK1 在拟南芥（Arabidopsis thaliana）中与 AP-2 相关联，但功能尚不清楚。在这里，遗传分析表明，拟南芥 aak1 和 ap2m 突变体的根向性生长都发生了改变，包括触感触和重力感应反应受损。在拟南芥中，AAK1 将 AP2M 磷酸化在 Thr-163 上，而在 ap2m 突变体中表达的 AP2M 的磷酸化无效形式导致类似于 aak1 的表型，而 AP2M 的磷酸化模拟形式则挽救了 aak1 突变体。此外，我们发现 AP2M 的 AAK1 依赖性磷酸化状态调节胞吞作用的频率分布。我们的数据表明，AAK1 对 Thr-163 上的 AP2M 磷酸化可微调拟南芥根中的胞吞作用，以控制其向性生长。
