The circadian clock is a timekeeping system for regulation of numerous biological daily rhythms. One characteristic of the circadian clock is that period length remains relatively constant in spite of environmental fluctuations, such as temperature change. Here, using the curated collection of in-house small molecule chemical library (ITbM chemical library), we show that small molecule 3,4-dibromo-7-azaindole (B-AZ) lengthened the circadian period of Arabidopsis thaliana (Arabidopsis). B-AZ has not previously been reported to have any biological and biochemical activities. Target identification can elucidate the mode of action of small molecules, but we were unable to make a molecular probe of B-AZ for target identification. Instead, we performed other analysis, gene expression profiling that potentially reveals mode of action of molecules. Short-term treatment of B-AZ decreased the expression of four dawn- and morning-phased clock-associated genes, CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1), LATE ELONGATED HYPOCOTYL (LHY), PSEUDO-RESPONSE REGULATOR 9 (PRR9) and PRR7. Consistently, amounts of PRR5 and TIMING OF CAB EXPRESSION 1 (TOC1) proteins, transcriptional repressors of CCA1, LHY, PRR9 and PRR7 were increased upon B-AZ treatment. B-AZ inhibited Casein Kinase 1 family (CK1) that phosphorylates PRR5 and TOC1 for targeted degradation. A docking study and molecular dynamics simulation suggested that B-AZ interacts with the ATP-binding pocket of human CK1 delta, whose amino acid sequences are highly similar to those of Arabidopsis CK1. B-AZ-induced period-lengthening effect was attenuated in prr5 toc1 mutants. Collectively, this study provides a novel and simple structure CK1 inhibitor that modulates circadian clock via accumulation of PRR5 and TOC1.

中文翻译：

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3,4-Dibromo-7-Azaindole通过抑制酪蛋白激酶1活性来调节拟南芥生物钟。

昼夜节律时钟是用于调节许多生物日常节律的计时系统。昼夜节律时钟的一个特征是，尽管环境变化（例如温度变化），周期长度仍保持相对恒定。在这里，使用内部小分子化学文库（ITbM化学文库）的精选馆藏，我们显示出小分子3,4-二溴7-氮杂吲哚（B-AZ）延长了拟南芥（Arabidopsis）的昼夜节律周期。以前没有报道B-AZ具有任何生物和生化活性。目标识别可以阐明小分子的作用方式，但是我们无法制作B-AZ分子探针来进行目标识别。相反，我们进行了其他分析，即潜在地揭示分子作用方式的基因表达谱分析。B-AZ的短期治疗降低了四个黎明和早晨阶段的时钟相关基因，CIRCADIAN时钟关联的1（CCA1），晚期加长的油菜籽（LHY），假性反应调节剂9（PRR9）和PRR7的表达。 。一致地，在B-AZ处理后，PRR5的量和CAB表达1（TOC1）蛋白质的定时，CCA1，LHY，PRR9和PRR7的转录阻遏物增加。B-AZ抑制酪蛋白激酶1家族（CK1）磷酸化PRR5和TOC1的靶向降解。对接研究和分子动力学模拟表明，B-AZ与人CK1δ的ATP结合口袋相互作用，后者的氨基酸序列与拟南芥CK1高度相似。B-AZ诱导的周期延长效应在prr5 toc1突变体中减弱。总的来说，