Module-specific regulation of the β-phaseolin promoter during embryogenesis
Module-specific regulation of the β-phaseolin promoter during embryogenesis
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DOI：
10.1046/j.1365-313x.2003.01678.x
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发表时间：
2003-03-01
期刊：
影响因子：
7.2
通讯作者：
Hall, TC
中科院分区：
文献类型：
--
作者：
Chandrasekharan, MB;Bishop, KJ;Hall, TC
phas 启动子表现出严格的空间调控，在菜豆（Phaseolus vulgaris）的胚胎发生过程中高度表达，而在营养发育的所有阶段完全沉默。这种模式在转基因烟草和拟南芥中得以保留，如下所示。硫酸二甲酯体内足迹分析表明，phas 启动子近端 295 bp 内的 20 多个顺式元件在种子组织中受到因子结合的保护，而在叶子中则没有结合。通过将定点取代突变掺入-295phas启动子内的10个位置，探索了这一复杂谱代表了几个模块（子叶、下胚轴和胚根）特异性因子-DNA相互作用的总和的假设。 G-box突变后，-295phas启动子活性仅保留2.6%；还发现CCAAAT盒、E盒和RY元件介导胚胎中的高水平表达。 CACA 元件具有双重正负调节作用，而豌豆球蛋白盒被认为是强负调节元件。近端（-70 至 -64）RY 基序被发现在下胚轴中表达，而所有 RY 元件都有助于子叶中的表达，但在胚胎发生过程中不参与维管组织的表达。位于-277至-271、-260至-254和-237至-231位置的RY元件被发现可协调根特异性抑制。 G-盒似乎是功能性脱落酸响应元件，而E-位点可能是偶联元件。结果证实了自给自足的顺式元件功能在胚胎发生过程中产生模块化模式的概念。它们还反映了顺式元素相互作用中冗余和层次结构的存在。重要的是，在所研究的两种远缘相关植物中观察到的几乎相同的表达模式有力地证明了所观察到的因子-元件相互作用的功能的普遍性。
The phas promoter displays stringent spatial regulation, being very highly expressed during embryogenesis and completely silent during all phases of vegetative development in bean, Phaseolus vulgaris . This pattern is maintained in transgenic tobacco and, as shown here, Arabidopsis . Dimethyl sulphate in vivo footprinting analyses revealed that over 20 cis- elements within the proximal 295 bp of the phas promoter are protected by factor binding in seed tissues whereas none are bound in leaves. The hypothesis that this complex profile represents a summation of several module (cotyledon, hypocotyl, and radicle)-specific factor-DNA interactions has been explored by the incorporation of site-directed substitution mutations into 10 locations within the -295phas promoter. Only 2.6% of -295phas promoter activity remained after mutation of the G -box; the CCAAAT box, the E -box and the RY elements were also found to mediate high levels of expression in embryos. Whereas the CACA element has dual positive and negative regulatory roles, the vicilin box was identified as a strong negative regulatory element. The proximal (-70 to -64) RY motif was found to bestow expression in the hypocotyl while all the RY elements contribute to expression in cotyledons but not to vascular tissue expression during embryogenesis. RY elements at positions -277 to -271, -260 to -254, and -237 to -231 were found to orchestrate radicle-specific repression. The G -box appears to be the functional abscisic acid responsive element and the E -site may be a coupling element. The results substantiate the concept that autarkical cis -element functions generate modular patterning during embryogenesis. They also reflect the existence of both redundancy and hierarchy in cis -element interactions. Importantly, the virtually identical expression patterns observed for the two distantly related plants studied argue strongly for the generality of function for the observed factor-element interactions.