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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.
Plant metallothioneins (MTs) are believed to play an important role in plant response to heavy metal stress, but the transcriptional regulation of this gene remains unclear.Our previous studies initially identified rice MT at -331 / -194 The promoter region of ricMT gene is necessary for the activation of ricMT by metal.In order to clarify the role of -331 / -194 promoter in the regulation of ricMT expression, we studied the binding properties of ricMT with this factor. The nuclei were extracted from young leaves of 2-week-old rice with almost no chloroplast contamination, and nuclear proteins were prepared for gel blocking experiments and found that nuclear factor could specifically bind to -331 / -194 promoter.This study further The effects of heavy metals on nuclear factor binding activity were investigated. It was found that in the binding system, heavy metal ions were removed and the binding capacity of nuclear factor to the -331 / -194 sequence was lost. However, heavy metal ions were added to the binding system, The increase in the concentration of added ions is enhanced to prove that this binding indeed relies on heavy metals.These evidence, combined with previous results, suggests that some metal-responsive NFs may By binding to -331 / -194 region of the promoter to regulate gene expression ricMT.