Calcium and cGMP target distinct phytochrome-responsive elements.
Calcium and cGMP target distinct phytochrome-responsive elements.
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钙和 cGMP 针对不同的光敏色素响应元素。
DOI：
10.1046/j.1365-313x.1996.10061149.x
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Chua,NH
中科院分区：
文献类型：
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作者：
Wu,Y;Hiratsuka,K;Neuhaus,G;Chua,NH
先前使用显微注射到番茄aureamutant的单细胞中的工作表明，光敏色素A依赖的rbc和rbcs基因的激活分别由钙和cGMP介导。这项工作试图确定响应这两种小分子的启动子顺式元件。盒II和单元I，分别来自rbcS-3A和chs启动子，先前被证明作为光响应元件。11个盒II拷贝和4个单元I拷贝分别连接到-90和-46 35 S启动子的5′端，并且两个构建体均与β-葡萄糖醛酸酶（GUS）报告基因融合。将Box II/-90GUS或Unit I/-46GUS与燕麦光敏色素A（phyA）和异三聚体G蛋白激活剂GTPγS共注射后获得了GUS活性。通过phyA激活Box II/-90 GUS对cGMP拮抗剂Rp-cGMPS不敏感，尽管在注射的细胞中花青素积累而不是叶绿体发育被完全阻断。与该结果一致，钙而不是cGMP诱导Box II/-90 GUS活性。与Box II/-90GUS相反，单元I/-46GUS活性的phyA依赖性激活被Rp-cGMPS阻断。此外，cGMP，而不是钙，诱导单位I/-46GUS活性。对照实验表明，-90 GUS和-46 GUS在钙和cGMP存在下分别无活性。这些结果提供了证据，表明盒II和单元I分别是钙和cGMP途径的靶点。有趣的是，盒II/-90GUS的钙激活被高浓度的cGMP抑制，单元I/-46GUS的cGMP诱导被高浓度的钙/CaM阻断。因此，这两个小顺式元件也可以作为相互控制机制的靶标，这些相互控制机制用于调节两个phyA信号传导分支的活动。
Previous work using microinjection into single cells of the tomatoaureamutant demonstrated that phytochrome A‐dependent activation ofrbcSandchsgenes was mediated by calcium and cGMP, respectively. This work sought to identify promotercis‐elements that respond to these two small molecules. Box II and Unit I, derived fromrbcS‐3Aandchspromoters, respectively, were previously shown to function as light‐responsivecis‐elements. Eleven copies of Box II and four copies of Unit I were linked 5′ to the −90 and −46 35 S promoters, respectively, and, both constructs were fused to the β‐glucuronidase (GUS) reporter gene. GUS activities were obtained upon co‐injection of either Box II/‐90GUS or Unit I/‐46GUS with oat phytochrome A (phyA) and GTPγS, an activator of heterotrimeric G proteins. The activation of Box II/‐90GUS by phyA was insensitive to the cGMP antagonist, Rp‐cGMPS, although anthocyanin accumulation, but not chloroplast development, was totally blocked in the injected cells. Consistent with this result, calcium, but not cGMP, induced Box II/‐90GUS activity. In contrast to Box II/‐90GUS, phyA‐dependent activation of Unit I/‐46GUS activity was blocked by Rp‐cGMPS. Moreover, cGMP, not calcium, induced Unit I/‐46GUS activity. Control experiments showed that −90 GUS and −46 GUS were inactive in the presence of calcium and cGMP, respectively. These results provide evidence that Box II and Unit I are targets of the calcium and cGMP pathways, respectively. Interestingly, calcium activation of Box II/‐90GUS was repressed by a high concentration of cGMP and cGMP induction of Unit I/‐46GUS was blocked by a high concentration of calcium/CaM. Thus, these two smallcis‐elements can also serve as targets of the reciprocal control mechanisms that operate to regulate the activities of the two phyA signaling branches.