Department of Applied Genetics and Cell Biology, Institute of Molecular Plant Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Muthgasse 18, 1190, Wien, Austria.
Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium.
Nat Commun. 2022 Sep 1;13(1):5147. doi: 10.1038/s41467-022-32888-8.
Directionality in the intercellular transport of the plant hormone auxin is determined by polar plasma membrane localization of PIN-FORMED (PIN) auxin transport proteins. However, apart from PIN phosphorylation at conserved motifs, no further determinants explicitly controlling polar PIN sorting decisions have been identified. Here we present Arabidopsis WAVY GROWTH 3 (WAV3) and closely related RING-finger E3 ubiquitin ligases, whose loss-of-function mutants show a striking apical-to-basal polarity switch in PIN2 localization in root meristem cells. WAV3 E3 ligases function as essential determinants for PIN polarity, acting independently from PINOID/WAG-dependent PIN phosphorylation. They antagonize ectopic deposition of de novo synthesized PIN proteins already immediately following completion of cell division, presumably via preventing PIN sorting into basal, ARF GEF-mediated trafficking. Our findings reveal an involvement of E3 ligases in the selective targeting of apically localized PINs in higher plants.
植物激素生长素的细胞间运输具有方向性，这是由 PIN 形成蛋白（PIN）生长素运输蛋白在质膜上的极性定位决定的。然而，除了在保守基序上的 PIN 磷酸化之外，没有进一步的决定因素明确控制极性 PIN 分拣决策。在这里，我们介绍了拟南芥 WAVY GROWTH 3（WAV3）和密切相关的 RING-finger E3 泛素连接酶，其功能丧失突变体在根分生组织细胞中表现出明显的 PIN2 定位的顶端到基部极性转换。WAV3 E3 连接酶作为 PIN 极性的必要决定因素，独立于 PINOID/WAG 依赖的 PIN 磷酸化起作用。它们拮抗新合成的 PIN 蛋白的异位沉积，这一过程在细胞分裂完成后立即发生，可能是通过阻止 PIN 分拣到 ARF GEF 介导的基底部运输。我们的研究结果揭示了 E3 连接酶在高等植物中选择性靶向顶端定位的 PIN 的作用。
