Structural Insight into DNA Recognition by CCT/NF-YB/YC Complexes in Plant Photoperiodic Flowering
Structural Insight into DNA Recognition by CCT/NF-YB/YC Complexes in Plant Photoperiodic Flowering
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植物光周期开花中 CCT/NF-YB/YC 复合物 DNA 识别的结构洞察
DOI：
10.1105/tpc.20.00067
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发表时间：
2020
期刊：
影响因子：
11.6
通讯作者：
Yongzhong Xing
中科院分区：
文献类型：
--
作者：
Cuicui Shen;Haiyang Liu;Zeyuan Guan;Yan Junjie;Zheng Ting;Wenhao Yan;Changyin Wu;Qifa Zhang;Ping Yin;Yongzhong Xing
含有CCT结构域的蛋白质是植物特有的一个大家族。它们转录调节光周期开花、昼夜节律、春化作用和其他相关过程。通过其CCT结构域，CONSTANS和HEADING DATE 1（HD 1）与核因子Y（NF-Y）B/C二聚体协调，特异性靶向其靶基因启动子内的保守“CCACA”基序。然而，CCT结构域识别DNA的机制仍不清楚。在这里，我们确定了水稻（Oryza sativa）NF-YB/YC二聚体和成花基因Heading date 3a（Hd 3a）结合的HD 1CCT/NF-YB/YC三聚体的晶体结构，分辨率分别为2.0 nm和2.55 nm。HD 1的CCT结构域具有两个α-螺旋和两个环的细长结构，将Hd 3连接到NF-YB/YC二聚体上。阻碍因子α2和环2锚定在'CCACA'基序的小沟中，其决定了特异性碱基识别。我们的结构揭示了CCT结构域，NF-YB/YC二聚体和靶DNA之间的相互作用机制。这些结果不仅提供了深入了解CCT蛋白和NF-Y亚基之间的网络，而且还提供了通过操纵成花素表达来提高作物生产力和全球适应性的潜在方法。
CONSTANS, CONSTANS-LIKE, and TIMING OF CAB EXPRESSION1 (CCT) domain-containing proteins are a large family unique to plants. They transcriptionally regulate photoperiodic flowering, circadian rhythms, vernalization, and other related processes. Through their CCT domains, CONSTANS and HEADING DATE1 (HD1) coordinate with the NUCLEAR FACTOR Y (NF-Y) B/C dimer to specifically target a conserved ‘CCACA’ motif within the promoters of their target genes. However, the mechanism underlying DNA recognition by the CCT domain remains unclear. Here we determined the crystal structures of the rice (Oryza sativa) NF-YB/YC dimer and the florigen geneHeading date 3a(Hd3a)-bound HD1CCT/NF-YB/YC trimer with resolutions of 2.0 Å and 2.55 Å, respectively. The CCT domain of HD1 displays an elongated structure containing two α-helices and two loops, tetheringHd3ato the NF-YB/YC dimer. Helix α2 and loop 2 are anchored into the minor groove of the ‘CCACA’ motif, which determines the specific base recognition. Our structures reveal the interaction mechanism among the CCT domain, NF-YB/YC dimer, and the target DNA. These results not only provide insight into the network between the CCT proteins and NF-Y subunits, but also offer potential approaches for improving productivity and global adaptability of crops by manipulating florigen expression.