Key message

CCA1α and CCA1β protein variants respond to environmental light and temperature cues, and higher temperature promotes CCA1β protein production and causes its retention detectable in the cytoplasm.

Abstract

CIRCADIAN CLOCK ASSOCIATED1 (CCA1), as the core transcription factor of circadian clock, is involved in the regulation of endogenous circadian rhythm in Arabidopsis. Previous studies have shown that CCA1 consists of two abundant splice variants, fully spliced CCA1α and intron-retaining CCA1β. CCA1β is believed to form a nonfunctional heterodimer with CCA1α and its closed-related homolog LHY. Many studies have established that CCA1β is a transcription product, while how CCA1β protein is produced and how two CCA1 isoforms respond to environmental cues have not been elucidated. In this study, we identified CCA1α and CCA1β protein variants under different photoperiods with warm or cold temperature cycles, respectively. Our results showed that CCA1 protein production is regulated by prolonged light exposure and warm temperature. The protein levels of CCA1α and CCA1β peak in the morning, but the detection of CCA1β is dependent on immunoprecipitation enrichment at 22 °C. Higher temperature of 37 °C promotes CCA1β protein production and causes its retention to be detectable in the cytoplasm. Overall, our results indicate that two splice variants of the CCA1 protein respond to environmental light and temperature signals and may, therefore, maintain the circadian rhythms and give individuals the ability to adapt to environment.

中文翻译：

---

温度适应过程中 CCA1 替代蛋白亚型的识别

关键信息

CCA1α 和 CCA1β 蛋白变体对环境光和温度提示有反应，较高的温度促进 CCA1β 蛋白的产生并导致其在细胞质中可检测到。

抽象的

CIRCADIAN CLOCK ASSOCIATED1 (CCA1) 作为生物钟的核心转录因子，参与拟南芥内源性昼夜节律的调控。先前的研究表明，CCA1由两个丰富的剪接变体组成，完全剪接的CCA1α和保留内含子的CCA1β。CCA1β 被认为与 CCA1α 及其闭合相关同源物 LHY 形成非功能性异二聚体。许多研究已经证实CCA1β是一种转录产物，而 CCA1β 蛋白是如何产生的以及两种 CCA1 同种型如何响应环境线索尚未阐明。在这项研究中，我们分别在不同的光周期和温暖或寒冷的温度循环下鉴定了 CCA1α 和 CCA1β 蛋白变体。我们的研究结果表明，CCA1 蛋白的产生受长时间光照和温暖温度的调节。CCA1α和CCA1β的蛋白质水平在早上达到峰值，但CCA1β的检测依赖于22°C的免疫沉淀富集。37 °C 的较高温度促进 CCA1β 蛋白的产生并导致其在细胞质中的保留可检测到。总的来说，我们的结果表明 CCA1 蛋白的两个剪接变体对环境光和温度信号有反应，因此，