Poulsen C, Chua N H
Laboratory of Plant Molecular Biology, Rockefeller University, New York, NY 10021-6399.
Mol Gen Genet. 1988 Sep;214(1):16-23. doi: 10.1007/BF00340173.
We have previously isolated and characterized a gene (rbcS-8B) from the wild-type species Nicotiana plumbaginifolia, encoding the small subunit of ribulose-1,5-bisphosphate carboxylase. Using transgenic N. plumbaginifolia as a host, we found that a 5' upstream region (-1038 to +32) of rbcS-8B contains all the sequences required for organ-specific and light-dependent expression of the gene. Here we report a detailed analysis of the 5' upstream region of rbcS-8B. Gene transfer experiments indicate that the region between -1038 to -102 contains at least two enhancer-like elements. The proximal element located between -312 and -102, confers organ-specific and light-inducible expression upon a reporter gene and closely resembles previously identified elements in other light-responsive plant genes. The distal element with novel characteristics is located between -1038 and -589. It can enhance expression from the cauliflower mosaic virus 35S promoter, but only when the -90 to -46 region of the 35S promoter is present. It confers on the heterologous promoter the organ-specificity of a typical rbcS gene but the enhanced transcription in leaves is insensitive to light. These experiments show for the first time that organ-specificity and light-responsiveness can be determined by separable cis-regulatory elements. The implications for the regulation of light-responsive genes are discussed.
我们先前已从野生型植物白花烟草中分离并鉴定了一个基因（rbcS - 8B），该基因编码核酮糖 - 1,5 - 二磷酸羧化酶的小亚基。以转基因白花烟草作为宿主，我们发现rbcS - 8B基因的5'上游区域（-1038至+32）包含该基因器官特异性和光依赖性表达所需的所有序列。在此，我们报告对rbcS - 8B基因5'上游区域的详细分析。基因转移实验表明，-1038至-102之间的区域至少包含两个增强子样元件。位于-312和-102之间的近端元件赋予报告基因器官特异性和光诱导性表达，并且与先前在其他光响应性植物基因中鉴定的元件非常相似。具有新特性的远端元件位于-1038和-589之间。它可以增强花椰菜花叶病毒35S启动子的表达，但仅当35S启动子的-90至-46区域存在时才起作用。它赋予异源启动子典型rbcS基因的器官特异性，但叶片中增强的转录对光不敏感。这些实验首次表明，器官特异性和光响应性可以由可分离的顺式调控元件决定。文中还讨论了其对光响应基因调控的意义。
