Gasser C S, Winter J A, Hironaka C M, Shah D M
Plant Molecular Biology, Monsanto Company, St. Louis, Missouri 63198.
J Biol Chem. 1988 Mar 25;263(9):4280-7.
5-Enolpyruvylshikimate-3-phosphate (EPSP) synthase is an enzyme of the shikimate pathway which is located in the chloroplasts in higher plants. This enzyme is the target of the nonselective herbicide glyphosate. We have isolated and sequenced cDNA clones encoding EPSP synthase from petunia and tomato. The deduced amino acid sequences of the two enzyme precursors show 93% identity in the mature protein regions and 58% identity in the transit peptides. The sequences of the plant enzymes show significantly greater similarity to bacterial EPSP synthases than to fungal EPSP synthases. A genomic clone containing an EPSP synthase gene was isolated from a library of petunia DNA and was shown to contain seven intervening sequences. This gene is expressed approximately 25-fold higher in flower petals than in other organs of petunia. Transcription of this gene is initiated at multiple sites in petunia leaves and in a glyphosate-tolerant petunia cell line overproducing EPSP synthase mRNA. In petals, however, transcription of this gene is initiated almost entirely from only one of these sites. In contrast to petunia, the levels of EPSP synthase mRNA in different organs of tomato do not differ significantly.
5-烯醇丙酮酰莽草酸-3-磷酸（EPSP）合酶是莽草酸途径中的一种酶，存在于高等植物的叶绿体中。这种酶是非选择性除草剂草甘膦的作用靶点。我们从矮牵牛和番茄中分离并测序了编码EPSP合酶的cDNA克隆。两种酶前体推导的氨基酸序列在成熟蛋白区域显示出93%的同一性，在转运肽区域显示出58%的同一性。植物酶的序列与细菌EPSP合酶的相似性明显高于与真菌EPSP合酶的相似性。从矮牵牛DNA文库中分离出一个包含EPSP合酶基因的基因组克隆，该克隆显示含有7个间隔序列。该基因在矮牵牛花瓣中的表达量比在矮牵牛的其他器官中高约25倍。该基因在矮牵牛叶片和过量产生EPSP合酶mRNA的耐草甘膦矮牵牛细胞系中的转录起始于多个位点。然而，在花瓣中，该基因的转录几乎完全仅从这些位点中的一个起始。与矮牵牛不同，番茄不同器官中EPSP合酶mRNA的水平没有显著差异。
