20190917 Developmental cell

Plasmodesmata
Sep 17, 2019
2 min read

Nucleo-cytoplasmic Partitioning of ARF Proteins Controls Auxin Responses in Arabidopsis thaliana

Samantha K. Powers, Alex S. Holehouse, David A. Korasick, Katherine H. Schreiber, Natalie M. Clark, Hongwei Jing, Ryan Emenecker, Soeun Han, Eric Tycksen, Ildoo Hwang, Rosangela Sozzani, Joseph M. Jez, Rohit V. Pappu, and Lucia C. Strader

Summary

The phytohormone auxin plays crucial roles in nearly every aspect of plant growth and development. The auxin response factor (ARF) transcription factor family regulates auxin-responsive gene expression and exhibits nuclear localization in regions of high auxin responsiveness. Here we show that the ARF7 and ARF19 proteins accumulate in micron-sized assemblies within the cytoplasm of tissues with attenuated auxin responsiveness. We found that the intrinsically disordered middle region and the folded PB1 interaction domain of ARFs drive protein assembly formation. Mutation of a single lysine within the PB1 domain abrogates cytoplasmic assemblies, promotes ARF nuclear localization, and results in an altered transcriptome and morphological defects. Our data suggest a model in which ARF nucleo-cytoplasmic partitioning regulates auxin responsiveness, providing a mechanism for cellular competence for auxin signaling.

生長素反應因子（ARF）在細胞核-細胞質的分隔控制了阿拉伯芥對於生長素的反應

總結

植物荷爾蒙生長素（auxin），在植物生長發育的各個階段幾乎都扮演了關鍵的角色。生長素反應因子蛋白（Auxin Response Factor, ARF）在高生長素的部位，會座落在細胞核的位置來調控下游生長素調控基因的表現。在此，我們顯示了，在對生長素有較延遲反應的部位，ARF7和ARF19會在細胞質累積並聚合成為微米尺寸的聚合體。我們發現，ARF蛋白質中的中段不規則折疊區域以及能摺疊成固定形態的PB1區域會一同驅使這個聚合體的生成。在PB1區域中，單一個離氨酸的突變即可廢除ARF蛋白質在細胞質中形成聚合體的能力，促進ARF蛋白質座落在細胞核，最後導致整個下游基因調控表現的改變並造成外表形態的變化。我們的結果顯示了一個可能的機制：生長素反應因子蛋白可利用調整在細胞核與細胞質之間的分隔，進而微調植物對於生長素的反應強度。