Zeng Qike, Song Li, Xia Mingzhe, Zheng Zai, Chen Ziang, Che Ximing, Liu Dong
MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences Tsinghua University Beijing China.
State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China Sichuan Agricultural University at Wenjiang Chengdu China.
Plant Direct. 2023 Aug 2;7(8):e517. doi: 10.1002/pld3.517. eCollection 2023 Aug.
AT-HOOK MOTIF NUCLEAR LOCALIZED (AHL) proteins occur in all sequenced plant species. They bind to the AT-rich DNA sequences in chromosomes and regulate gene transcription related to diverse biological processes. However, the molecular mechanism underlying how AHL proteins regulate gene transcription is poorly understood. In this research, we used root hair production as a readout to study the function of two Arabidopsis AHL proteins, AHL17, and its closest homolog AHL28. Overexpression of or greatly enhanced root hair production by increasing the transcription of an array of genes downstream of RHD6. RHD6 is a key transcription factor that regulates root hair development. Mutation of completely suppressed the overproduction of root hairs by blocking the transcription of -activated genes. The overexpression of or , however, neither affected the transcription of nor the accumulation of RHD6 protein. These two AHL proteins also did not directly interact with RHD6. Furthermore, we found that three members of the Heat Shock Protein70 family, which have been annotated as the subunits of the plant Mediator complex, could form a complex with both AHL17 and RHD6. Our research might reveal a previously unrecognized mechanism of how AHL proteins regulate gene transcription.
AT钩基序核定位（AHL）蛋白存在于所有已测序的植物物种中。它们与染色体中富含AT的DNA序列结合，并调节与多种生物学过程相关的基因转录。然而，人们对AHL蛋白如何调节基因转录的分子机制了解甚少。在本研究中，我们以根毛产生作为指标来研究两种拟南芥AHL蛋白AHL17及其最接近的同源物AHL28的功能。AHL17或AHL28的过表达通过增加RHD6下游一系列基因的转录，极大地促进了根毛的产生。RHD6是调节根毛发育的关键转录因子。AHL17的突变通过阻断AHL17激活基因的转录，完全抑制了根毛的过度产生。然而，AHL17或AHL28的过表达既不影响RHD6的转录，也不影响RHD6蛋白的积累。这两种AHL蛋白也不与RHD6直接相互作用。此外，我们发现热休克蛋白70家族的三个成员，它们已被注释为植物中介复合体的亚基，可以与AHL17和RHD6形成复合体。我们的研究可能揭示了一种以前未被认识的AHL蛋白调节基因转录的机制。
