A Role for Protein Kinase Casein Kinase2 α-Subunits in the Arabidopsis Circadian Clock
A Role for Protein Kinase Casein Kinase2 α-Subunits in the Arabidopsis Circadian Clock
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DOI：
10.1104/pp.111.179846
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发表时间：
2011-11-01
期刊：
影响因子：
7.4
通讯作者：
Lin, Chentao
中科院分区：
文献类型：
--
作者：
Lu, Sheen X.;Liu, Hongtao;Lin, Chentao
昼夜节律是一种自我调节的内源性节律，周期约为24小时。从细菌到人类的生物体中，生物钟调节着各种各样的生理和分子过程。时钟蛋白的磷酸化在产生适当的昼夜节律中起着关键作用。酪蛋白激酶2（CK 2）是一种进化上保守的丝氨酸/苏氨酸蛋白激酶，由两个催化α亚基和两个调节β亚基组成。虽然大多数负责昼夜节律功能的分子组分在界之间不保守，但CK 2是调节基本时钟蛋白的稳定性和亚细胞定位的高度保守的时钟组分。在这里，我们研究了cka 1a 2a 3三重突变体对拟南芥（Arabidopsis thaliana）生物钟的影响。三个核定位CK 2 α亚基的功能丧失突变导致各种昼夜输出节律和中央时钟基因表达的周期延长，表明cka 1a 2a 3三重突变体影响昼夜时钟的步伐。此外，cka 1a 2a 3三重突变体在体外具有降低的CK 2激酶活性和昼夜节律相关1磷酸化水平。最后，我们发现，光周期开花反应，这是由昼夜节律调节，减少在cka 1a 2a 3三重突变体和植物开花后，在长日照条件下。这些数据表明，CK 2 α亚基是拟南芥昼夜节律系统的重要组成部分，它们对节律的影响部分是由于它们的昼夜时钟相关1的磷酸化。
Circadian rhythms are autoregulatory, endogenous rhythms with a period of approximately 24 h. A wide variety of physiological and molecular processes are regulated by the circadian clock in organisms ranging from bacteria to humans. Phosphorylation of clock proteins plays a critical role in generating proper circadian rhythms. Casein Kinase2 (CK2) is an evolutionarily conserved serine/threonine protein kinase composed of two catalytic alpha-subunits and two regulatory beta-subunits. Although most of the molecular components responsible for circadian function are not conserved between kingdoms, CK2 is a well-conserved clock component modulating the stability and subcellular localization of essential clock proteins. Here, we examined the effects of a cka1a2a3 triple mutant on the Arabidopsis (Arabidopsis thaliana) circadian clock. Loss-of-function mutations in three nuclear-localized CK2 alpha subunits result in period lengthening of various circadian output rhythms and central clock gene expression, demonstrating that the cka1a2a3 triple mutant affects the pace of the circadian clock. Additionally, the cka1a2a3 triple mutant has reduced levels of CK2 kinase activity and CIRCADIAN CLOCK ASSOCIATED1 phosphorylation in vitro. Finally, we found that the photoperiodic flowering response, which is regulated by circadian rhythms, was reduced in the cka1a2a3 triple mutant and that the plants flowered later under long-day conditions. These data demonstrate that CK2 alpha subunits are important components of the Arabidopsis circadian system and their effects on rhythms are in part due to their phosphorylation of CIRCADIAN CLOCK ASSOCIATED1.