【摘要】 植物金属硫蛋白(metallothioneins,MT)被认为在植物应答重金属胁迫方面发挥了重要作用,但该基因的转录调控机制目前仍不清楚.我们以前的研究初步鉴定出位于-331/-194的水稻MT基因(ricMT)启动子区对于金属激活ricMT的表达是必需的.为了明确-331/-194启动子序列在控制ricMT表达中的作用,本课题开展了该序列与核因子的结合特性研究.从2周龄水稻嫩叶中提取了几乎不含叶绿体污染的细胞核,并制备了核蛋白用于凝胶阻滞实验,发现核因子能够与-331/-194启动子序列特异结合.本研究还进一步考察了重金属对核因子结合活性的影响,发现在结合体系中去除重金属离子,核因子与-331/-194序列的结合能力会丧失,而在结合体系中加入重金属离子,结合能力则会随着外加的离子浓度提高而增强,证明这种结合确实依赖于重金属.这些证据结合以前的结果表明,某些金属响应的核因子可能通过结合-331/-194启动子区域来调控ricMT基因表达.更多还原

【Abstract】 Plant metallothioneins(MT) are believed to play an essential role in response to heavy metal stress,but the mechanism in transcription regulation remains unknown.Our previous study has identified that the-331 to-194 region in the rice MT gene(ricMT) promoter was required for the metal-activated expression of ricMT.We further explored the binding characteristic of this DNA sequence with nuclear factors.Nuclei with low contamination of chloroplasts were isolated from 2-week rice seedling leaves and nuclear proteins were prepared for electrophoretic mobility shift assay(EMSA).Nuclear factors were detected to specifically bind to the-331/-194 fragment and their binding activities were explored.The results showed that the binding could be abolished with the depletion of heavy metals,and enhanced by adding exogenous heavy metal ions,suggesting that some metal-responsive nuclear factors might be involved in metalloregulation of ricMT expression by binding to the-331/-194 promoter region.更多还原