Multiple bHLH proteins form heterodimers to mediate CRY2-dependent regulation of flowering-time in Arabidopsis.
Multiple bHLH proteins form heterodimers to mediate CRY2-dependent regulation of flowering-time in Arabidopsis.
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多种 bHLH 蛋白形成异二聚体，介导拟南芥开花时间的 CRY2 依赖性调节。
DOI：
10.1371/journal.pgen.1003861
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发表时间：
2013
期刊：
影响因子：
4.5
通讯作者：
Lin C
中科院分区：
文献类型：
--
作者：
Liu Y;Li X;Li K;Liu H;Lin C
拟南芥隐花色素2（Cryptochrome 2，CX 2）介导光对开花时间的调控。CIB 1（BH 2-interacting bHLH 1）特异性地响应蓝光与BH 2相互作用以激活FT（开花位点T）的转录。在体外，CIB 1以比其与非经典E-box（CANNTG）DNA序列的相互作用高得多的亲和力与经典E-box（CACGTG，也称为G-box）结合。然而，在体内，CIB 1结合到FT启动子的染色质区域，其仅包含非典型的E-box序列。在这里，我们表明，在蓝光的作用下，CIB 2也至少与CIB 5相互作用，但在黑暗中或对其他波长的光的作用下则不起作用。我们的遗传分析表明，CIB 1，CIB 2，CIB 4，和CIB 5的行为冗余激活FT的转录，他们是积极的调节因子的FAB 2介导的开花。更重要的是，CIB 1和其他CIB蛋白形成异源二聚体，并且在体外DNA结合测定中，一些异源二聚体比CIB同二聚体对非典型E盒具有更高的结合亲和力。这一结果解释了为什么在体外CIB 1和其他CIBs以更高的亲和力结合到典型的E-box（G-box），而在体内它们都与FT启动子处的非典型的E-box相关。与不同的CIB蛋白在β 2介导的蓝光信号传导中发挥相似作用的假设一致，CIB蛋白的表达受到蓝光的特异性调节。我们的研究表明，CIBs的功能冗余调节E12依赖的开花，不同的CIBs形成异二聚体与非典型的E-box DNA在体内相互作用。 拟南芥（Arabidopsis thaliana）蓝光受体隐花色素（cryptochromes，CIB）通过与CIB 1（CIB 2-interacting bHLH 1）相互作用来调控开花时间。然而，目前还不清楚蓝光依赖的CIB 2-CIB 1相互作用如何影响FT转录。我们在这里报告，除了CIB 1，BH 2也与CIB 1相关的bHLH蛋白，CIBs相互作用。这些CIB与CIB 1冗余地激活FT的转录和开花。更重要的是，CIB 1和CIB可以形成异源二聚体，并且这些异源二聚体中的一些对非规范E-box具有更高的结合亲和力，尽管它们的同源二聚体都偏好规范E-box（G-box），因此它们可以结合FT启动子的非规范E-box序列。这是植物中bHLH的异源二聚化可以改变DNA结合亲和力或特异性的第一个例子。CIB蛋白参与蓝光信号传导，并且它们被蓝光特异性地稳定。
Arabidopsis thaliana cryptochrome 2 (CRY2) mediates light control of flowering time. CIB1 (CRY2-interacting bHLH 1) specifically interacts with CRY2 in response to blue light to activate the transcription of FT (Flowering Locus T). In vitro, CIB1 binds to the canonical E-box (CACGTG, also referred to as G-box) with much higher affinity than its interaction with non-canonical E-box (CANNTG) DNA sequences. However, in vivo, CIB1 binds to the chromatin region of the FT promoter, which only contains the non-canonical E-box sequences. Here, we show that CRY2 also interacts with at least CIB5, in response to blue light, but not in darkness or in response to other wavelengths of light. Our genetic analysis demonstrates that CIB1, CIB2, CIB4, and CIB5 act redundantly to activate the transcription of FT and that they are positive regulators of CRY2 mediated flowering. More importantly, CIB1 and other CIBs proteins form heterodimers, and some of the heterodimers have a higher binding affinity than the CIB homodimers to the non-canonical E-box in the in vitro DNA-binding assays. This result explains why in vitro CIB1 and other CIBs bind to the canonical E-box (G-box) with a higher affinity, whereas they are all associated with the non-canonical E-boxes at the FT promoter in vivo. Consistent with the hypothesis that different CIB proteins play similar roles in the CRY2-midiated blue light signaling, the expression of CIB proteins is regulated specifically by blue light. Our study demonstrates that CIBs function redundantly in regulating CRY2-dependent flowering, and that different CIBs form heterodimers to interact with the non-canonical E-box DNA in vivo. Arabidopsis thaliana blue light receptor cryptochromes (CRYs) mediate light control of flowering time by interacting with CIB1 (CRY2-interacting bHLH1) in response to blue light. However, it remains unclear how the blue light-dependent CRY2-CIB1 interaction affects the FT transcription. We report here that in addition to CIB1, CRY2 also interact with CIB1 related bHLH proteins, CIBs. These CIBs act redundantly with CIB1 to activate the transcription of FT and flowering. More importantly, CIB1 and the CIBs can form heterodimers and some of those heterodimers have a higher binding affinity to the non-canonical E-box, although their homodimers all prefer canonical E-box (G-box), so they can bind to the non-canonical E-Box sequences of the FT promoter. This is the first example in plants that heterodimerization of bHLH can change the DNA binding affinity or specificity. CIB proteins are involved in blue light signaling and they are specifically stabilized by blue light.
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影响因子：
48
作者：
Kennedy, Matthew J.;Hughes, Robert M.;Peteya, Leslie A.;Schwartz, Joel W.;Ehlers, Michael D.;Tucker, Chandra L.
通讯作者：
Tucker, Chandra L.
影响因子：
3.8
作者：
Hong, Shin-Young;Seo, Pil Joon;Park, Chung-Mo
通讯作者：
Park, Chung-Mo
影响因子：
7.2
作者：
Clough, RC;Jordan-Beebe, ET;Vierstra, RD
通讯作者：
Vierstra, RD
影响因子：
7.2
作者：
Clough, SJ;Bent, AF
通讯作者：
Bent, AF
DOI：
10.1073/pnas.1211305109
发表时间：
2012-08-28
影响因子：
11.1
作者：
Idevall-Hagren, Olof;Dickson, Eamonn J.;De Camilli, Pietro
通讯作者：
De Camilli, Pietro