转录因子SOC1调控植物花期转变的分子机制研究

被子植物的适时开花是完成有性生殖的重要生理条件，植物通过复杂且精确的开花信号通路整合外界环境因素和内源遗传因子影响，精准调控开花时间。拟南芥作为兼性长日照植物，在光周期途径、温度途径、赤霉素途径、年龄途径、春化途径、自主途径等多条开花途径协同作用下，确定从营养生长到生殖生长过渡的最适时间，在几个开花整合基因的调控下，促进花器官的形成，从而控制拟南芥开花。其中，SUPPRESSOR OF OVEREXPRESSION OF CO 1（SOC1）作为重要的开花整合转录因子，能够整合来自不同开花途径的信号，促进花器官的形成，在拟南芥花期调控中发挥了至关重要的作用。

本论文主要围绕拟南芥SOC1蛋白开展了结构生物学研究。SOC1作为拟南芥开花整合因子，已被证明能够结合SOC1基因启动子，通过正反馈调节在短时间内达到SOC1蛋白的快速积累。本研究首先解析了SOC1 1-86蛋白和DNA的复合物晶体结构，阐明了SOC1以同源二聚体的形式特异性识别底物DNA的分子机制，为进一步揭示SOC1蛋白作为开花整合因子在花期调控中的正反馈调节机制提供分子结构基础。同时，AGL24和SVP同为MADS-box蛋白家族的成员，已被证明能够与SOC1蛋白形成异源二聚体，进而调控下游基因的表达。本研究分别尝试纯化SOC1-AGL24和SOC1-SVP复合物，并对MBP-SOC1全长蛋白的酶切条件进行摸索，为正确组装SOC1-AGL24-DNA和SOC1-SVP-DNA的三元复合物提供思路。最后提出SOC1蛋白通过组装不同异源二聚体使下游花分生组织基因LFY的DNA发生环化的结构模型。

综上所述，本论文重点以SOC1蛋白及其复合物为切入点，通过结构生物学与生物化学的方法，研究SOC1蛋白在拟南芥花期调控中发挥不同作用的分子机制，有利于理解MADS-box家族蛋白中如何以不同异源二聚体的形式调控基因表达，对于进一步探索开花整合因子的调控机制具有重要意义。

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