莽草酸途径
芳香族氨基酸
生物化学
代谢途径
莽草酸
生物合成
酶
生物
氨基酸
质体
新陈代谢
基因
叶绿体
作者
Klaus M. Herrmann,Lisa M. Weaver
出处
期刊:Annual review of plant physiology and plant molecular biology
[Annual Reviews]
日期:1999-06-01
卷期号:50 (1): 473-503
被引量:1116
标识
DOI:10.1146/annurev.arplant.50.1.473
摘要
▪ Abstract The shikimate pathway links metabolism of carbohydrates to biosynthesis of aromatic compounds. In a sequence of seven metabolic steps, phosphoenolpyruvate and erythrose 4-phosphate are converted to chorismate, the precursor of the aromatic amino acids and many aromatic secondary metabolites. All pathway intermediates can also be considered branch point compounds that may serve as substrates for other metabolic pathways. The shikimate pathway is found only in microorganisms and plants, never in animals. All enzymes of this pathway have been obtained in pure form from prokaryotic and eukaryotic sources and their respective DNAs have been characterized from several organisms. The cDNAs of higher plants encode proteins with amino terminal signal sequences for plastid import, suggesting that plastids are the exclusive locale for chorismate biosynthesis. In microorganisms, the shikimate pathway is regulated by feedback inhibition and by repression of the first enzyme. In higher plants, no physiological feedback inhibitor has been identified, suggesting that pathway regulation may occur exclusively at the genetic level. This difference between microorganisms and plants is reflected in the unusually large variation in the primary structures of the respective first enzymes. Several of the pathway enzymes occur in isoenzymic forms whose expression varies with changing environmental conditions and, within the plant, from organ to organ. The penultimate enzyme of the pathway is the sole target for the herbicide glyphosate. Glyphosate-tolerant transgenic plants are at the core of novel weed control systems for several crop plants.
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