拟南芥中MRG2与BAF60相互作用的研究

Investigation of the Interaction between MRG2 and BAF60 in Arabidopsis thaliana

拟南芥MRG2(Morf Related Genes 2)是MRG蛋白家族成员之一,可以识别组蛋白H3K4和H3K36甲基化修饰,但是对于它是否具有其他生物学功能,目前了解还非常有限.我们首先通过免疫共沉淀结合质谱分析获得了MRG2结合蛋白,并对其中一个染色质重塑SWI/SNF复合体亚基BAF60蛋白进行了深入研究.体外Pull-down和双荧光互补实验证实了MRG2和BAF60在植物体内体外都能相互作用.已有研究表明:BAF60抑制异戊烯转移酶IPT(ISOPENTENYL TRANSFERASE)基因转录.RNA-seq和RT-qPCR数据都表明在mrg1mrg2双突变拟南芥植株中多个IPT基因转录水平明显升高.ChIP实验结果证明MRG2蛋白富集于IPT3基因编码区.综上所述,在植物细胞中MRG2和BAF60蛋白相互作用共同调控了IPT3基因的转录.这些研究对于理解MRG2在基因表达调控方面的功能具有重要意义.

MRG2(Morf Related Genes 2)belongs to the MRG protein family and functions as a reader protein of tri-methylated histone H3 lysine 4 and histone H3 lysine 36 in Arabidopsis.Here we identified the BAF60 subunit of the SWI/SNF chromatin remodeling complex as the MRG2 binding protein using co-immunoprecipitation and mass spectrometry.Using the pull-down and bimolecular fluorescence complementation assays,we found that MRG2 and BAF60 proteins interact with each other in vitro and in vivo.It has been reported that BAF60 down-regulates the expression of IPT(ISOPENTENYL TRANSFERASE)gene.Interestingly,RNA-seq and RT-qPCR results showed that the expression levels of IPT3,IPT5,and IPT7 in mrg1mrg2 double mutant were obviously increased compared with those in wild type.ChIP assay demonstrated that MRG2 protein is enriched in the coding region of IPT3.These results indicate that MRG2 and BAF60 work together to regulate the expression of IPT3.