THE PROOFREADING OF HYDROXY ANALOGS OF LEUCINE AND ISOLEUCINE BY LEUCYL-TRANSFER RNA-SYNTHETASES FROM ESCHERICHIA-COLI AND YEAST
THE PROOFREADING OF HYDROXY ANALOGS OF LEUCINE AND ISOLEUCINE BY LEUCYL-TRANSFER RNA-SYNTHETASES FROM ESCHERICHIA-COLI AND YEAST
复制标题
DOI：
10.1093/nar/14.19.7529
复制
发表时间：
1986-10-10
影响因子：
14.9
通讯作者：
CRAMER, F
中科院分区：
文献类型：
--
作者：
ENGLISCH, S;ENGLISCH, U;CRAMER, F
合成了三种亮氨酸和异亮氨酸的类似物，分别在γ-或δ-或γ-和δ-位置上携带羟基，并在大肠杆菌和酵母的亮氨酸- trna合成酶的氨基酰化中进行了测试。正如化学校对模型中提出的那样，这些类似物和同型半胱氨酸的水解校对应该导致这些化合物的内酯化，因此提供了关于这两种亮氨酸- trna合成酶的校对机制的信息。大肠杆菌的亮氨酸- trna合成酶具有较高的初始底物识别能力。只有两个类似物，γ-羟基亮氨酸和同型半胱氨酸被激活并转移到tRNALeúwhere，发生转移后校对。γ-羟基亮氨酸和同型半胱氨酸内酯化。来自酵母的亮氨酸- trna合成酶对这些底物的初始鉴别能力相对较差，这可以通过在氨酰腺苷酸水平上非常有效的转移前校对来补偿。未检测到内化或误充trnaleui。
Three analogues each of leucine and isoleucine carrying hydroxy groups in γ- or δ- or γ- and δ-position have been synthesized, and tested in the aminoacylation by leucyl-tRNA synthetases from E. coli and yeast. Hydrolytic proofreading, as proposed in the chemical proofreading model, of these analogues and of homocysteine should result in a lactonisation of these compounds and therefore provide information regarding the proofreading mechanism of the two leucyl-tRNA synthetases.Leucyl-tRNA synthetase from E. coli shows a high initial substrate discrimination. Only two analogues, γ-hydroxyleucine and homocysteine are activated and transferred to tRNALeúwhere a post-transfer proofreading occurs. Lactonisation of γ-hydroxyleucine and homocysteine could be detected.Leucyl-tRNA synthetase from yeast has a relatively poor initial discrimination of these substrates, which is compensated by a very effective pre-transfer proofreading on the aminoacyl-adenylate level. No lactonisation nor mischarged tRNALeuis detectable.