雷竹和拟南芥SOC1多聚体差异性分析

Oligomeric status of the SOC1 gene from Phyllostachys violascens and Arabidopsis thaliana

MADS-box是一个超家族基因,可通过形成多聚体复合物实现对花发育的调控。其中SUPPRESSOR OF OVEREXPRESSION OF CO1(SOC1)作为MADS-box家族的重要成员,对花形成时间起决定作用。作为转录因子蛋白,SOC1包含MADS,I,K和C 4个独特功能的结构域,发挥功能的过程中,其中K结构域能够调控同源或是异源蛋白多聚体的形成,I结构域能够稳定转录因子结合DNA的作用。在单子叶植物雷竹Phyllostachys violascens和拟南芥Arabidopsis thaliana中,开花时间模式上存在明显差异,前者开花时间不确定,后者是确定的。尽管不能直接推断这种现象与SOC1形成植物不同复合物相关联,但雷竹和拟南芥SOC1是否具有形成相同模式的复合物对于竹类植物开花时间的研究具有重要意义。以雷竹和拟南芥SOC1作为研究对象,通过酵母双杂交实验,重点分析SOC1在形成多聚体模式方面的差异性。结果表明:拟南芥SOC1能形成同源二聚体,并且可通过结构域是I和K区形成同源多聚体;而雷竹SOC1不能形成多聚体,但可以通过K结构域形成同源二聚体。因此,I结构域可能是引起拟南芥和雷竹SOC1多聚体状态不同的一个原因,这个结构域是否对开花定时起决定作用还有待进一步转基因功能验证。

MADS-box genes are a super family, which can form different polymers to mediate the development of floral primordia and floral organs. The important one of MADs-box genes, SOC1 [suppressor of overexpression of cytochrome oxidase 1], determine the flowering time. The MADS-box transcription factor, SOC1 contains four different functions domains: MADS, I, K, and C. The K domain controls the homologous or heterologous protein polymer formation. The I domain could stabilize the MADS-box proteins binding the DNA. In order to control the floral development, MADS-box proteins can form different complex. Visible difference in floral timing is demonstrated in Phyllostachys violascens and Arabidopsis thaliana. A. thaliana is certain in floral timing while Phyllostachys violascens is not. Though we cannot compare the difference in floral timing with the difference in SOC1 complex formation, it is still interesting. MADS-box genes such as SOC1 containing four different functions: MADS, I, K and C, control floral timing. To determine whether SOC1's from different species demonstrated similar patterns in forming a complex, this study analyzed the differences of polymer formation for SOC1 that originated from Phyllostachys violascens and Arabidopsis thaliana using a yeast two-hybrid assay. Results of the assay showed that the full-length At SOC1 gene from A. thaliana formed strong homopolymers with the I and K domains being the main regions for formation of the interaction. However, the fulllength SOC1 from Phyllostachys violascens(Pv SOC1) did not form a homodimer. Thus, even though the K protein domain could form a homodimer, the presence of the I protein domain disrupted the dimer meaning the I domain could be a key factor in SOC1 polymer formation; the role of the I domain in floral timing should be verified with a plant transgene study.