A Competitive Peptide Inhibitor KIDARI Negatively Regulates HFR1 by Forming Nonfunctional Heterodimers in Arabidopsis Photomorphogenesis
A Competitive Peptide Inhibitor KIDARI Negatively Regulates HFR1 by Forming Nonfunctional Heterodimers in Arabidopsis Photomorphogenesis
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DOI：
10.1007/s10059-013-2159-2
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发表时间：
2013-01-01
影响因子：
3.8
通讯作者：
Park, Chung-Mo
中科院分区：
文献类型：
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作者：
Hong, Shin-Young;Seo, Pil Joon;Park, Chung-Mo
动态二聚体的形成是一个复杂的手段，调节转录因子的活动在不同的细胞过程。例如，碱性螺旋-环-螺旋（bHLH）转录因子长下胚轴远红1（HFR 1）通过与光敏色素相互作用因子（PIF）形成非DNA结合异二聚体在植物光形态建成中发挥作用。最近的研究表明，一个小的HLH蛋白KIDARI（KDR）负调控HFR 1的活性在这个过程中。然而，KDR控制HFR 1活性的分子机制尚不清楚。在这里，我们证明KDR通过竞争性地形成非功能性异源二聚体来减弱HFR 1活性，从而导致PIF 4从转录失活的HFR 1-PIF 4复合物中释放。因此，KDR共表达可以抑制HFR 1过表达植物的光形态发生下胚轴生长，如在HFR 1缺陷型hfr 1 -201突变体中所观察到的。这些结果表明，PIF 4活性是通过HFR 1和KDR的双层竞争性抑制来调节的，这反过来又可以确保在波动的光照条件下对PIF 4活性进行微调。
Dynamic dimer formation is an elaborate means of modulating transcription factor activities in diverse cellular processes. The basic helix-loop-helix (bHLH) transcription factor LONG HYPOCOTYL IN FAR-RED 1 (HFR1), for example, plays a role in plant photomorphogenesis by forming non-DNA binding heterodimers with PHYTOCHROME-INTERACTING FACTORS (PIFs). Recent studies have shown that a small HLH protein KIDARI (KDR) negatively regulates the HFR1 activity in the process. However, molecular mechanisms underlying the KDR control of the HFR1 activity are unknown. Here, we demonstrate that KDR attenuates the HFR1 activity by competitively forming nonfunctional heterodimers, causing liberation of PIF4 from the transcriptionally inactive HFR1-PIF4 complex. Accordingly, the photomorphogenic hypocotyl growth of the HFR1-overexpres-sing plants can be suppressed by KDR coexpression, as observed in the HFR1-deficient hfr1-201 mutant. These results indicate that the PIF4 activity is modulated through a double layer of competitive inhibition by HFR1 and KDR, which could in turn ensure fine-tuning of the PIF4 activity under fluctuating light conditions.