TMK1-mediated auxin signalling regulates differential growth of the apical hook
TMK1-mediated auxin signalling regulates differential growth of the apical hook
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DOI：
10.1038/s41586-019-1069-7
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发表时间：
2019-04-11
期刊：
影响因子：
64.8
通讯作者：
Xu, Tongda
中科院分区：
文献类型：
--
作者：
Cao, Min;Chen, Rong;Xu, Tongda
植物激素生长素在植物生长发育的几乎所有方面都起着至关重要的作用。生长素在不同组织中的浓度不同，调节不同的发育结果，并有助于生长素功能的多样性。然而，这些活动背后的机制却鲜为人知。在这里，我们确定了一种生长素信号转导机制，该机制与基于运输抑制反应1(TIR1)和其他生长素受体F-box(AFB)家族蛋白(TIR1/AFB受体)(1，2)的典型生长素途径平行，在顶钩发育过程中将细胞生长素水平翻译为介导差异生长。这一信号机制作用于顶端挂钩的凹侧，并涉及生长素介导的跨膜蛋白1(TMk1)的C末端切割。TMk1的胞浆和胞核易位的C末端与生长素或吲哚-3-乙酸(AUX/IAA)家族的两个非规范转录抑制物(IAA32和IAA34)特异性地相互作用并使其磷酸化，从而调节ARF转录因子。与AUX/IAA转录抑制物在规范途径中的降解相反，新发现的机制稳定了非规范的IAA32和IAA34转录抑制物，调节基因表达，最终抑制生长。生长素-MK1信号通路起源于细胞表面，由高水平的生长素触发，与TIR1/AFB信号通路共享一组部分重叠的转录因子。这允许对不同浓度的细胞生长素进行不同的解释，从而使这种多功能的信号分子能够调节复杂的发育结果。
The plant hormone auxin has crucial roles in almost all aspects of plant growth and development. Concentrations of auxin vary across different tissues, mediating distinct developmental outcomes and contributing to the functional diversity of auxin. However, the mechanisms that underlie these activities are poorly understood. Here we identify an auxin signalling mechanism, which acts in parallel to the canonical auxin pathway based on the transport inhibitor response1 (TIR1) and other auxin receptor F-box (AFB) family proteins (TIR1/AFB receptors)(1,2), that translates levels of cellular auxin to mediate differential growth during apical-hook development. This signalling mechanism operates at the concave side of the apical hook, and involves auxin-mediated C-terminal cleavage of transmembrane kinase 1 (TMK1). The cytosolic and nucleus-translocated C terminus of TMK1 specifically interacts with and phosphorylates two non-canonical transcriptional repressors of the auxin or indole-3-acetic acid (Aux/IAA) family (IAA32 and IAA34), thereby regulating ARF transcription factors. In contrast to the degradation of Aux/IAA transcriptional repressors in the canonical pathway, the newly identified mechanism stabilizes the non-canonical IAA32 and IAA34 transcriptional repressors to regulate gene expression and ultimately inhibit growth. The auxin-MK1 signalling pathway originates at the cell surface, is triggered by high levels of auxin and shares a partially overlapping set of transcription factors with the TIR1/AFB signalling pathway. This allows distinct interpretations of different concentrations of cellular auxin, and thus enables this versatile signalling molecule to mediate complex developmental outcomes.