Chien Chin-I, Chen Yu-Wei, Wu Yi-Hua, Chang Chih-Yao, Wang Tzu-Ling, Wang Chien-Chia
Department of Life Sciences, National Central University, Jung-li, Taiwan.
Department of Neurology, Landseed Hospital, Ping-jen, Taiwan.
PLoS One. 2014 Apr 17;9(4):e94659. doi: 10.1371/journal.pone.0094659. eCollection 2014.
Two oligomeric types of glycyl-tRNA synthetase (GlyRS) are found in nature: a α2 type and a α2β2 type. The former has been identified in all three kingdoms of life and often pairs with tRNAGly that carries an A73 discriminator base, while the latter is found only in bacteria and chloroplasts and is almost always coupled with tRNAGly that contains U73. In the yeast Saccharomyces cerevisiae, a single GlyRS gene, GRS1, provides both the cytoplasmic and mitochondrial functions, and tRNAGly isoacceptors in both compartments possess A73. We showed herein that Homo sapiens and Arabidopsis thaliana cytoplasmic GlyRSs (both α2-type enzymes) can rescue both the cytoplasmic and mitochondrial defects of a yeast grs1- strain, while Escherichia coli GlyRS (a α2β2-type enzyme) and A. thaliana organellar GlyRS (a (αβ)2-type enzyme) failed to rescue either defect of the yeast mull allele. However, a head-to-tail αβ fusion of E. coli GlyRS effectively supported the mitochondrial function. Our study suggests that a α2-type eukaryotic GlyRS may be functionally substituted with a α2β2-type bacterial cognate enzyme despite their remote evolutionary relationships.
在自然界中发现了两种寡聚类型的甘氨酰 - tRNA合成酶（GlyRS）：α2型和α2β2型。前者在所有三个生命王国中都已被鉴定出来，并且通常与携带A73判别碱基的tRNAGly配对，而后者仅在细菌和叶绿体中发现，并且几乎总是与含有U73的tRNAGly偶联。在酿酒酵母中，单个GlyRS基因GRS1提供细胞质和线粒体功能，并且两个区室中的tRNAGly同工受体都具有A73。我们在此表明，人类和拟南芥的细胞质GlyRS（均为α2型酶）可以挽救酵母grs1-菌株的细胞质和线粒体缺陷，而大肠杆菌GlyRS（α2β2型酶）和拟南芥细胞器GlyRS（(αβ)2型酶）未能挽救酵母mull等位基因的任何一种缺陷。然而，大肠杆菌GlyRS的头对尾αβ融合有效地支持了线粒体功能。我们的研究表明，尽管α2型真核GlyRS与α2β2型细菌同源酶的进化关系较远，但在功能上可能被其替代。
