Agricultural Products Department, E. I. du Pont de Nemours & Co., Experimental Station E402, Wilmington, DE 19880-0402.
Proc Natl Acad Sci U S A. 1989 Jun;86(11):4179-83. doi: 10.1073/pnas.86.11.4179.
Acetolactate synthase (ALS; EC 4.1.3.18) is the first common enzyme in the biosynthetic pathways leading to leucine, isoleucine, and valine. It is the target enzyme for three classes of structurally unrelated herbicides, the sulfonylureas, the imidazolinones, and the triazolopyrimidines. A cloned ALS gene from the small cruciferous plant Arabidopsis thaliana has been fused to bacterial transcription/translation signals and the resulting plasmid has been used to transform Escherichia coli. The cloned plant gene, which includes sequences encoding the chloroplast transit peptide, is functionally expressed in the bacteria. It is able to complement genetically a strain of E. coli that lacks endogenous ALS activity. An ALS gene cloned from a line of Arabidopsis previously shown to be resistant to sulfonylurea herbicides has been similarly expressed in E. coli. The herbicide-resistance phenotype is expressed in the bacteria, as assayed by both enzyme activity and the ability to grow in the presence of herbicides. This system has been useful for purifying substantial amounts of the plant enzyme, for studying the sequence parameters involved in subcellular protein localization, and for characterizing the interactions that occur between ALS and its various inhibitors.
乙酰乳酸合成酶（ALS；EC 4.1.3.18）是导致亮氨酸、异亮氨酸和缬氨酸生物合成途径中的第一个共同酶。它是三类结构上无关的除草剂的靶酶，即磺酰脲类、咪唑啉酮类和三唑嘧啶类。从小的十字花科植物拟南芥中克隆的 ALS 基因已与细菌转录/翻译信号融合，并且所得质粒已用于转化大肠杆菌。克隆的植物基因包括编码叶绿体转运肽的序列，在细菌中具有功能性表达。它能够在遗传上补充缺乏内源性 ALS 活性的大肠杆菌菌株。从先前显示对磺酰脲类除草剂具有抗性的拟南芥品系中克隆的 ALS 基因已在大肠杆菌中类似表达。通过酶活性和在除草剂存在下生长的能力来测定，该除草剂抗性表型在细菌中表达。该系统已可用于纯化大量植物酶，用于研究参与亚细胞蛋白定位的序列参数，并用于表征 ALS 与其各种抑制剂之间发生的相互作用。
