LUX ARRHYTHMO encodes a Myb domain protein essential for circadian rhythms
LUX ARRHYTHMO encodes a Myb domain protein essential for circadian rhythms
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DOI：
10.1073/pnas.0503029102
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发表时间：
2005-07-19
影响因子：
11.1
通讯作者：
Kay, SA
中科院分区：
文献类型：
--
作者：
Hazen, SP;Schultz, TF;Kay, SA
在高等植物中，昼夜节律时钟协调诸如光信号和向开花过渡等基本过程。我们通过筛选具有长下胚轴表型的幼苗，并随后检测时钟调节的CAB2::LUC异常表达，从拟南芥诱变报告系中分离出生物钟突变体。该筛选发现了一个时钟基因LUX心律失常（LUX）的五个突变等位基因，它们在恒定白光和黑暗条件下显著影响节律的幅度和稳健性。此外，这些突变体从营养发育到花发育的转变加快，下胚轴伸长在光照和黑暗循环下得到加强。我们通过高密度寡核苷酸阵列基因分型的整体分离分析，将这些突变定位为与拟南芥中其他时钟成分和反应调节因子相关的一个小的Myb转录因子。拟南芥生物钟的负臂，circadian clock ASSOCIATED （CCA1）和LATE ELONGATED HYPOCOTYL (LHY)，在lux突变体中被抑制，而CAB2表达的时序（TOC1）被激活。我们发现CCA1和LHY结合到LUX启动子的晚上元件基序上，这强烈表明这些蛋白抑制LUX的表达，就像它们抑制TOC1一样。这些数据也与LUX对于CCA1和LHY表达的激活是必要的一致。
In higher plants, the circadian clock orchestrates fundamental processes such as light signaling and the transition to flowering. We isolated mutants of the circadian clock from an Arabidopsis thaliana mutagenized reporter line by screening for seedlings with long hypocotyl phenotypes and subsequently assaying for abnormal clock-regulated CAB2::LUC expression. This screen identified five mutant alleles of a clock gene, LUX ARRHYTHMO (LUX), that significantly affect amplitude and robustness of rhythms in both constant white light and dark conditions. In addition, the transition from vegetative to floral development is accelerated and hypocotyl elongation is accentuated in these mutants under light:dark cycles. We genetically mapped the mutations by bulk segregant analysis with high-density oligonucleotide array genotyping to a small putative Myb transcription factor related to other clock components and response regulators in Arabidopsis. The negative arm of the Arabidopsis circadian clock, CIRCADIAN CLOCK ASSOCIATED (CCA1) and LATE ELONGATED HYPOCOTYL (LHY), is repressed in the lux mutants, whereas TIMING OF CAB2 EXPRESSION (TOC1) is activated. We demonstrate that CCA1 and LHY bind to the evening element motif in the LUX promoter, which strongly suggests that these proteins repress LUX expression, as they do TOC1. The data are also consistent with LUX being necessary for activation of CCA1 and LHY expression.