Meinnel T, Mechulam Y, Le Corre D, Panvert M, Blanquet S, Fayat G
Laboratoire de Biochimie, Unité Associée 240 du Centre National de la Recherche Scientifique, Ecole Polytechnique, Palaiseau, France.
Proc Natl Acad Sci U S A. 1991 Jan 1;88(1):291-5. doi: 10.1073/pnas.88.1.291.
Accurate aminoacylation of a tRNA by Escherichia coli methionyl-tRNA synthetase (MTS) is specified by the CAU anticodon. A genetic screening procedure was designed to isolate MTS mutants able to aminoacylate a methionine amber tRNA (CUA anticodon). Selected suppressor MTS enzymes all possess one or several mutations in the vicinity of Trp-461, a residue that is the major contributor to the stability of complexes formed with tRNAs having the cognate CAU anticodon. Analysis of catalytic properties of purified suppressor enzymes shows that they have acquired an additional specificity toward the amber anticodon without complete disruption of the methionine anticodon site. It is concluded that both positive and negative discrimination toward the binding of tRNA anticodon sequences is restricted to a limited region of the synthetase, residues 451-467.
大肠杆菌甲硫氨酰 - tRNA合成酶（MTS）对tRNA的准确氨酰化作用由CAU反密码子决定。设计了一种遗传筛选程序，以分离能够对甲硫氨酸琥珀色tRNA（CUA反密码子）进行氨酰化的MTS突变体。所选的抑制性MTS酶在Trp - 461附近均具有一个或几个突变，Trp - 461是与具有同源CAU反密码子的tRNA形成复合物稳定性的主要贡献残基。对纯化的抑制性酶的催化特性分析表明，它们对琥珀色反密码子获得了额外的特异性，而不会完全破坏甲硫氨酸反密码子位点。得出的结论是，对tRNA反密码子序列结合的正向和负向识别都局限于合成酶的一个有限区域，即残基451 - 467。
