National Key Laboratory of Plant Molecular Genetics and Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China.
Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, School of Life Sciences, Institute of Plant and Food Science, Southern University of Science and Technology, Shenzhen 518055, China.
Plant Cell. 2021 May 31;33(4):1182-1195. doi: 10.1093/plcell/koab016.
Flowering plants sense various environmental and endogenous signals to trigger the floral transition and start the reproductive growth cycle. CONSTANS (CO) is a master transcription factor in the photoperiod floral pathway that integrates upstream signals and activates the florigen gene FLOWERING LOCUS T (FT). Here, we performed comprehensive structural and biochemical analyses to study the molecular mechanism underlying the regulation of FT by CO in Arabidopsis thaliana. We show that the four previously characterized cis-elements in the FT promoter proximal region, CORE1, CORE2, P1, and P2, are all direct CO binding sites. Structural analysis of CO in complex with NUCLEAR FACTOR-YB/YC (NF-YB/YC) and the CORE2 or CORE1 elements revealed the molecular basis for the specific recognition of the shared TGTG motifs. Biochemical analysis suggested that CO might form a homomultimeric assembly via its N-terminal B-Box domain and simultaneously occupy multiple cis-elements within the FT promoter. We suggest that this multivalent binding gives the CO-NF-Y complex high affinity and specificity for FT promoter binding. Overall, our data provide a detailed molecular model for the regulation of FT by the master transcription factor complex CO-NF-Y during the floral transition.
开花植物通过感知各种环境和内源性信号来触发花发育转变并启动生殖生长周期。CONSTANS（CO）是光周期花发育途径中的主要转录因子，它整合上游信号并激活花发育基因 FLOWERING LOCUS T（FT）。在这里，我们进行了全面的结构和生化分析，以研究 CO 在拟南芥中调控 FT 的分子机制。我们表明，FT 启动子近端区域中以前鉴定的四个顺式元件（CORE1、CORE2、P1 和 P2）都是 CO 的直接结合位点。CO 与核因子-YB/YC（NF-YB/YC）和 CORE2 或 CORE1 元件复合物的结构分析揭示了对共享 TGTG 基序进行特异性识别的分子基础。生化分析表明，CO 可能通过其 N 端 B-Box 结构域形成同源多聚体组装，并同时占据 FT 启动子内的多个顺式元件。我们认为这种多价结合使 CO-NF-Y 复合物对 FT 启动子具有高亲和力和特异性。总的来说，我们的数据为在花发育转变过程中主要转录因子复合物 CO-NF-Y 对 FT 的调控提供了详细的分子模型。
