Cysteinyl-tRNA synthetase: determination of the last E. coli aminoacyl-tRNA synthetase primary structure.
Cysteinyl-tRNA synthetase: determination of the last E. coli aminoacyl-tRNA synthetase primary structure.
复制标题
半胱氨酰-tRNA合成酶：最后的大肠杆菌氨酰-tRNA合成酶一级结构的测定。
作者：
G. Eriani;Guy Dirheimer;J. Gangloff
在高温（43℃）条件下，通过对半胱氨酸- trna合成酶活性不足的菌株进行互补，分离出大肠杆菌半胱氨酸- trna合成酶（cysS）的编码基因。对一个2.1 kbp的DNA片段进行测序，发现一个1383 bp的开放阅读框，编码一个461个氨基酸残基的蛋白质，Mr为52,280，这与纯化后的蛋白质所观察到的值非常接近，该蛋白质表现为单体。CysRS序列具有典型的His-Ile- Gly - his （HIGH）和Lys-Met-Ser-Lys-Ser （KMSKS）基序，这是一类含有罗斯曼折叠的酶的特征；此外，它与MetRS（677个残基的同型二聚体）有显著的同源性，与Ile-、Leu-和ValRS（分别为939、860和951个残基的单体）有较小程度的同源性。由于其单体状态和较小的体积，CysRS可能与原始氨基酰基- trna合成酶关系更密切，而所有这些合成酶都是从原始氨基酰基- trna合成酶分化而来的。
The gene coding for E. coli cysteinyl-tRNA synthetase (cysS) was isolated by complementation of a strain deficient in cysteinyl-tRNA synthetase activity at high temperature (43 degrees C). Sequencing of a 2.1 kbp DNA fragment revealed an open reading frame of 1383 bp coding for a protein of 461 amino acid residues with a Mr of 52,280, a value in close agreement with that observed for the purified protein, which behaves as a monomer. The sequence of CysRS bears the canonical His-Ile- Gly -His (HIGH) and Lys-Met-Ser-Lys-Ser (KMSKS) motifs characteristic of the group of enzymes containing a Rossmann fold; furthermore, it shows striking homologies with MetRS (an homodimer of 677 residues) and to a lesser extent with Ile-, Leu-, and ValRS (monomers of 939, 860, and 951 residues respectively). With its monomeric state and smaller size, CysRS is probably more closely related to the primordial aminoacyl-tRNA synthetase from which all have diverged.