Abas Lindy, Benjamins René, Malenica Nenad, Paciorek Tomasz, Wiśniewska Justyna, Moulinier-Anzola Jeanette C, Sieberer Tobias, Friml Jirí, Luschnig Christian
Institute for Applied Genetics and Cell Biology, University of Natural Resources and Applied Life Sciences - BOKU, Muthgasse 18, A-1190 Wien, Austria.
Nat Cell Biol. 2006 Mar;8(3):249-56. doi: 10.1038/ncb1369. Epub 2006 Feb 19.
Root gravitropism describes the orientation of root growth along the gravity vector and is mediated by differential cell elongation in the root meristem. This response requires the coordinated, asymmetric distribution of the phytohormone auxin within the root meristem, and depends on the concerted activities of PIN proteins and AUX1 - members of the auxin transport pathway. Here, we show that intracellular trafficking and proteasome activity combine to control PIN2 degradation during root gravitropism. Following gravi-stimulation, proteasome-dependent variations in PIN2 localization and degradation at the upper and lower sides of the root result in asymmetric distribution of PIN2. Ubiquitination of PIN2 occurs in a proteasome-dependent manner, indicating that the proteasome is involved in the control of PIN2 turnover. Stabilization of PIN2 affects its abundance and distribution, and leads to defects in auxin distribution and gravitropic responses. We describe the effects of auxin on PIN2 localization and protein levels, indicating that redistribution of auxin during the gravitropic response may be involved in the regulation of PIN2 protein.
根向重力性描述了根沿着重力向量的生长方向，它由根分生组织中细胞的差异伸长介导。这种反应需要植物激素生长素在根分生组织内协调、不对称分布，并依赖于生长素运输途径中的PIN蛋白和AUX1成员的协同作用。在这里，我们表明细胞内运输和蛋白酶体活性共同控制根向重力性过程中PIN2的降解。重力刺激后，蛋白酶体依赖的PIN2在根上侧和下侧的定位和降解变化导致PIN2的不对称分布。PIN2的泛素化以蛋白酶体依赖的方式发生，表明蛋白酶体参与PIN2周转的控制。PIN2的稳定化影响其丰度和分布，并导致生长素分布和向重力性反应缺陷。我们描述了生长素对PIN2定位和蛋白水平的影响，表明重力反应过程中生长素的重新分布可能参与PIN2蛋白的调节。
