The Arabidopsis pseudo-response regulators, PRR5 and PRR7, coordinately play essential roles for circadian clock function
The Arabidopsis pseudo-response regulators, PRR5 and PRR7, coordinately play essential roles for circadian clock function
复制标题
DOI：
10.1093/pcp/pci061
复制
发表时间：
2005-04-01
影响因子：
4.9
通讯作者：
Mizuno, T
中科院分区：
文献类型：
--
作者：
Nakamichi, N;Kita, M;Mizuno, T
在拟南芥中，已经确定了一些与时钟相关的蛋白因子。其中，TOC1(CAB表达式1的定时)被认为是中央振荡器的组件。TOC1是拟南芥伪反应调节蛋白家族中的一员，包括PRR1/TOC1、PRR3、PRR5、PRR7和PRR9。目前还不能确定PRR家族的其他成员是否也与时钟功能本身有关。为了阐明这个问题，我们在这里构建了一个双突变系，该突变系被认为在PRR5和PRR7基因中都有严重的损伤。由此产生的纯合子prr5-11、prr7-11幼苗在去黄化过程中表现出明显的红光低敏表型。此外，它们在长日照光周期条件下表现出极晚开花的表型，而在短日照条件下表现出极晚开花的表型。在双突变植物中，当它们被释放到连续光(LL)和黑暗(DD)中时，某些钟控基因转录水平的节律被严重扰乱。观察到的表型最好的解释是“在LL和DD中都有心律失常”和/或“波幅显著降低的非常短的周期”。即使在光夹带(LD)条件下，突变植株也表现出异常的昼夜振荡特征，改变了某些时钟控制基因的幅度和/或相位，包括时钟成分CCA1(昼夜时钟相关1)基因。即使在温度夹带的条件下也能观察到这样的事件，这表明prr5-11 prr7-11损伤不能简单地归因于光信号输入途径的缺陷。与之前观察到的每一个突变体的表型相比，双突变体的这些多效性昼夜节律相关的表型非常显著。综合这些结果，我们首次提出PRR5和PRR7协同(或协同)在中央振荡器附近发挥重要的时钟相关作用。
In Arabidopsis thaliana, a number of clock-associated protein factors have been identified. Among them, TOC1 (TIMING OF CAB EXPRESSION 1) is believed to be a component of the central oscillator. TOC1 is a member of a small family of proteins, designated as ARABIDOPSIS PSEUDO-RESPONSE REGULATOR, including PRR1/TOC1, PRR3, PRR5, PRR7 and PRR9. It has not been certain whether or not other PRR family members are also implicated in clock function per se. To clarify this problem, here we constructed a double mutant line, which is assumed to have severe lesions in both the PRR5 and PRR7 genes. Resulting homozygous prr5-11 prr7-11 young seedlings showed a marked phenotype of hyposensitivity to red light during de-etiolation. In addition, they displayed a phenotype of extremely late flowering under long-day photoperiod conditions, but not short-day conditions. The rhythms at the level of transcription of certain clock-controlled genes were severely perturbed in the double mutant plants when they were released into continuous light (LL) and darkness (DD). The observed phenotype was best interpreted as 'arrhythmic in both LL and DD' and/or 'very short period with markedly reduced amplitude'. Even under the light entrainment (LD) conditions, the mutant plants showed anomalous diurnal oscillation profiles with altered amplitude and/or phase with regard to certain clock-controlled genes, including the clock component CCA1 (CIRCADIAN CLOCK-ASSOCIATED 1) gene. Such events were observed even under temperature entrainment conditions, suggesting that the prr5-11 prr7-11 lesions cannot simply be attributed to a defect in the light signal input pathway. These pleiotropic circadian-associated phenotypes of the double mutant were very remarkable, as compared with those observed previously for each single mutant. Taking these results together, we propose for the first time that PRR5 and PRR7 coordinately (or synergistically) play essential clock-associated roles close to the central oscillator.