为了深入研究调控芥菜开花信号整合子的两个核心转录因子Flowering Locus C(FLC)和SHOTR VEGETATIVE PHASE(SVP)的作用机理和进行人工调控,以芥菜‘QJ’为材料,采用RT-PCR技术分别扩增FLC和SVP的编码序列,构建原核表达质粒pET43.1a-FLC、pET43.1a-SVP,转化宿主菌大肠杆菌BL21,通过SDS-PAGE检测该蛋白的表达。利用免疫共沉淀原理及pET43.1a-FLC、pET43.1a-SVP融合蛋白序列中的6×His标签能与Ni+结合的特点,对芥菜FLC与SVP的相互作用进行SDS-PAGE检测。结果表明:FLC与SVP能在体外相互作用并形成复合体,为深入分析FLC与SVP间的作用机理以及探讨其与下游开花信号整合子元件的相互作用提供了理论和技术基础。
为了深入研究芥菜开花整合子SOC1基因的表达调控机制,利用染色体步移法从芥菜‘QJ’中克隆了SOC1编码区上游782 bp的启动子,并构建SOC1基因启动子的酵母表达载体p Ab Ai-SOC1,与蛋白表达载体p GADT7-FLC、p GADT7-SVP共转化酵母Y1HGold菌株。酵母单杂交表明:芥菜FLC和SVP蛋白均能与SOC1的启动子相互作用。进一步分析发现:SOC1启动子含3个CAr G-box表达调控基序。分别亚克隆这3个基因片段(SOC1-1、SOC1-2和SOC1-3),并再次构建酵母重组质粒p Ab Ai-SOC1-1、pA b Ai-SOC1-2和p Ab Ai-SOC1-3,与p GADT7-FLC、p GADT7-SVP分别融合到Y1HGold菌株。融合菌株均能在相应SD/-Leu/Ab A培养基上生长,说明SOC1-1、SOC1-2和SOC1-3都能被芥菜FLC、SVP蛋白识别并结合。再次构建SOC1-1、SOC1-2、SOC1-3的CAr G-box删除突变体及A-T互换突变体,则均不能与FLC、SVP蛋白互作。由此说明:SOC1-1、SOC1-2和SOC1-3的3个CAr G-box基序确实能特异性识别FLC、SVP,发生DNA—蛋白相互作用。这为利用启动子调控SOC1基因的转录表达等深入研究奠定了理论基础。
Site-specifc recognition modules with DNA nuclease have tremendous potential as molecular tools for genome targeting.The type III transcription activator-like effectors(TALEs)contain a DNA binding domain consisting of tandem repeats that can be engineered to bind user-defned specifc DNA sequences.We demonstrated that customized TALE-based nucleases(TALENs),constructed using a method called"unit assembly",specifcally target the endogenous FRIGIDA gene in Brassica oleracea L.var.capitata L.The results indicate that the TALENs bound to the target site and cleaved double-strand DNA in vitro and in vivo,whereas the effector binding elements have a 23 bp spacer.The T7 endonuclease I assay and sequencing data show that TALENs made double-strand breaks,which were repaired by a non-homologous end-joining pathway within the target sequence.These data show the feasibility of applying customized TALENs to target and modify the genome with deletions in those organisms that are still in lacking gene target methods to provide germplasms in breeding improvement.
Zijian SunNianzu LiGuodong HuangJunqiang XuYu PanZhimin WangQinglin TangMing SongXiaojia Wang
为深入研究芥菜开花信号整合子的两个核心调节因子SHORT VEGETATIVE PHASE(SVP)与FLOWERING LOCUS C(FLC)相互作用的分子机理,通过PCR扩增,从芥菜材料‘QJ’中分别克隆含EcoRⅠ/BamHⅠ双酶切位点的SVP和FLC编码区全长,并利用酵母双杂交体系,将FLC与GAL4报告基因DNA激活域融合(pGADT7FLC),SVP与GAL4报告基因DNA结合域融合(pGBKT7SVP)。两种重组质粒分别转化酵母Y187和Y2HGold后未出现自激活和毒性现象。融合的二倍体酵母(pGADT7FLC×pGBKT7SVP)能在选择性固体培养基QDO/X/A(SD/-Ade/-His/-Leu/-Trp/X-α-Gal/AbA)上生长,并且菌落呈蓝色。将诱饵质粒(pGBKT7SVP)与猎物质粒(pGADT7FLC)载体互换(pGADT7SVP、pGBKT7FLC),再次转化酵母后仍能融合成二倍体酵母(pGADT7SVP×pGBKT7FLC),并同时激活报告基因AUR1-C、HIS3、ADE2、MEL1,由此表明SVP与FLC蛋白能够相互结合。
