Dickey L F, Gallo-Meagher M, Thompson W F
Department of Botany, North Carolina State University, Raleigh 27695-7612.
EMBO J. 1992 Jun;11(6):2311-7. doi: 10.1002/j.1460-2075.1992.tb05290.x.
We have previously shown that element(s) mediating a light-induced increase in the abundance of Fed-1 mRNA in the leaves of transgenic tobacco plants are located within the transcribed portion of the gene. As part of an effort to define the mechanism of this effect, we report here that cis-acting elements capable of mediating a 5-fold light-induced increase in the abundance of this mRNA are located within a region comprising the 5' leader and first third of the Fed-1 coding sequence. No activity was detected in the 3' untranslated region of the gene. In a gain-of-function assay, the 5' region was found to be capable of conferring light responsiveness on three different reporter sequences, although experiments with the gusA reporter were complicated by an apparent negative light effect on the stability of this mRNA. Deletion experiments show that at least one essential light regulatory element is located in the 5' untranslated region of Fed-1 between nucleotides +19 and +57. Additional Fed-1 sequences, including a portion of the protein coding region, are required to confer positive responsiveness on the gusA reporter. These additional sequences may include specific light regulatory elements or simply provide an environment in which the leader element can function normally.
我们之前已经表明，介导转基因烟草植株叶片中Fed-1 mRNA丰度光诱导增加的元件位于该基因的转录区域内。作为确定这种效应机制工作的一部分，我们在此报告，能够介导该mRNA丰度5倍光诱导增加的顺式作用元件位于包含Fed-1编码序列的5'前导序列和前三分之一的区域内。在该基因的3'非翻译区未检测到活性。在功能获得分析中，发现5'区域能够赋予三种不同报告序列光响应性，尽管用gusA报告基因进行的实验因该mRNA稳定性上明显的负光效应而变得复杂。缺失实验表明，至少一个必需的光调节元件位于Fed-1的5'非翻译区核苷酸+19和+57之间。赋予gusA报告基因正响应性需要额外的Fed-1序列，包括部分蛋白质编码区。这些额外的序列可能包括特定的光调节元件，或者仅仅提供一个前导元件能够正常发挥功能的环境。
