Sequence determination and modeling of structural motifs for the smallest monomeric aminoacyl-tRNA synthetase.
Sequence determination and modeling of structural motifs for the smallest monomeric aminoacyl-tRNA synthetase.
复制标题
最小单体氨酰-tRNA 合成酶的序列测定和结构基序建模。
DOI：
10.1073/pnas.88.3.976
复制
发表时间：
1991
影响因子：
11.1
通讯作者：
Schimmel,P
中科院分区：
文献类型：
--
作者：
Hou,YM;Shiba,K;Mottes,C;Schimmel,P
先前研究的19种大肠杆菌氨基酰基trna合成酶的多肽链长达951个氨基酸，并且根据酶的不同，具有α， α 2， α 2和α 4的四级结构。这些酶被分为两类，这两类是由与特定三维结构相关的序列基序定义的。我们对大肠杆菌半胱氨酸- trna合成酶基因（EC 6.1.1.16）进行了分离、克隆和测序，发现该基因编码461个氨基酸的蛋白。生化分析证实该蛋白为单体，从而确定该酶为已知最小的单体合成酶。该序列表明，半胱氨酸- trna合成酶是一类酶，与一个亚群最密切相关，该亚群包括更大的蛋氨酸-、异亮氨酸-、亮氨酸-和缬氨酸- trna合成酶，其大小从677到951个氨基酸。半胱氨酸酶的氨基末端293氨基酸可以建模为一个核苷酸结合折叠，由于两个插入的截断使折叠分裂，该折叠比其最接近的亲属更紧密。这种较小的核苷酸结合折叠是半胱氨酸酶缩小尺寸的主要原因，并确定了该区域在I类酶亚群的五个成员中收缩的结构极限。
Polypeptide chains of 19 previously studied Escherichia coli aminoacyl-tRNA synthetases are as large as 951 amino acids and, depending on the enzyme, have quaternary structures of alpha, alpha 2, alpha 2 beta 2, and alpha 4. These enzymes have been organized into two classes which are defined by sequence motifs that are associated with specific three-dimensional structures. We isolated, cloned, and sequenced the previously uncharacterized gene for E. coli cysteine-tRNA synthetase (EC 6.1.1.16) and showed that it encodes a protein of 461 amino acids. Biochemical analysis established that the protein is a monomer, thus establishing this enzyme as the smallest known monomeric synthetase. The sequence shows that cysteine-tRNA synthetase is a class I enzyme that is most closely related to a subgroup that includes the much larger methionine-, isoleucine-, leucine-, and valine-tRNA synthetases, which range in size from 677 to 951 amino acids. The amino-terminal 293 amino acids of the cysteine enzyme can be modeled as a nucleotide-binding fold that is more compact than that of its closest relatives by virtue of truncations of two insertions that split the fold. This smaller nucleotide-binding fold accounts for much of the reduced size of the cysteine enzyme and establishes the limit to which the structure of this domain is contracted in the five members of this subgroup of class I enzymes.