PRR7 protein levels are regulated by light and the circadian clock in Arabidopsis
PRR7 protein levels are regulated by light and the circadian clock in Arabidopsis
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DOI：
10.1111/j.1365-313x.2007.03258.x
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发表时间：
2007-11-01
期刊：
影响因子：
7.2
通讯作者：
Kay, Steve A.
中科院分区：
文献类型：
--
作者：
Farre, Eva M.;Kay, Steve A.
在许多生物体中，互锁的转录环和受调节的蛋白质降解是产生自我维持的昼夜节律的主要机制。在拟南芥中，首次提出的调控转录环涉及转录因子CIRCADIAN CLOCK ASSOCIATED （CCA1）和LATE ELONGATED HYPOCOTYL （LHY）以及叶绿素A/B BINDING PROTEIN （TOC1/PRR1）的伪响应调控时序。最近的研究结果表明，TOC1同源物PRR7和PRR9也可能参与CCA1和LHY的转录调控环。在这项研究中，我们发现PRR7在拟南芥中的过度表达会导致昼夜节律严重受损。这些转基因品系显示CCA1和LHY RNA水平显著降低，进一步证明了PRR7与这些转录因子之间存在转录反馈回路。此外，我们发现PRR7蛋白以昼夜节律调节的方式磷酸化，其水平在翻译后受到昼夜和昼夜机制的调节。因此，拟南芥昼夜节律振荡器很可能通过转录和转录后机制参与光/暗周期。
Interlocking transcriptional loops and regulated protein degradation are the principal mechanisms involved in the generation of self-sustaining circadian rhythms in many organisms. In Arabidopsis the first proposed regulatory transcriptional loop involved the transcription factors CIRCADIAN CLOCK ASSOCIATED (CCA1) and LATE ELONGATED HYPOCOTYL (LHY) and the pseudo-response regulator TIMING OF CHLOROPHYLL A/B BINDING PROTEIN (TOC1/PRR1). Recent findings indicate that the TOC1 homologues PRR7 and PRR9 might also be involved in transcriptional regulatory loops with CCA1 and LHY. In this study we show that the overexpression of PRR7 in Arabidopsis leads to severely compromised circadian rhythms. These transgenic lines display significantly reduced levels of CCA1 and LHY RNA, providing further evidence for a transcriptional feedback loop between PRR7 and these transcription factors. In addition, we show that the PRR7 protein is phosphorylated in a circadian regulated manner and that its levels are post-translationally regulated by both diurnal and circadian mechanisms. The Arabidopsis circadian oscillator is therefore likely to be entrained to light/dark cycles both through transcriptional and post-transcriptional mechanisms.