亮氨酰-tRNA合成酶在體內(nèi)負(fù)責(zé)催化亮氨酸和對(duì)應(yīng)tRNA之間的酯化反應(yīng),，生成亮氨酰-tRNA為蛋白質(zhì)生物合成提供原料。根據(jù)特定插入序列在結(jié)構(gòu)中的空間位置以及有無(wú)特征的延伸結(jié)構(gòu)域,，亮氨酰-tRNA合成酶被劃分為細(xì)菌類(lèi),、古菌類(lèi)和真核類(lèi)。與原核來(lái)源的亮氨酰-tRNA合成酶相比,，真核以及古菌類(lèi)亮氨酰-tRNA合成酶在進(jìn)化的過(guò)程中獲得了許多獨(dú)特的功能未知的結(jié)構(gòu)元件,，亮氨酸專(zhuān)一結(jié)構(gòu)域1( leucine-specific-domain 1,LSD-1）就是其中之一。
中科院上海生命科學(xué)研究院生物化學(xué)與細(xì)胞生物學(xué)研究所王恩多研究組近日在Biochemical Journal上發(fā)表了該小組最新研究論文：原核與真核生物亮氨酰-tRNA合成酶的亮氨酸專(zhuān)一結(jié)構(gòu)域1的功能鑒定,。
王恩多實(shí)驗(yàn)室的周小龍博士研究了古菌和真核來(lái)源的亮氨酰-tRNA合成酶的LSD-1元件,，結(jié)果發(fā)現(xiàn)，在古菌和真核亮氨酰-tRNA合成酶共有的LSD-1區(qū)域引入突變時(shí)會(huì)顯著降低酶的氨基酸活化活力,，而幾乎不影響tRNA氨基?；幕盍Α５珜⒄婧肆涟滨?tRNA合成酶的LSD-1特有的延長(zhǎng)部分突變后會(huì)嚴(yán)重影響其tRNA氨基?；盍?。
該研究揭示了LSD-1結(jié)構(gòu)域在亮氨酰-tRNA合成酶催化過(guò)程的作用：不參與轉(zhuǎn)移后編校反應(yīng),，維持了tRNA氨基酰化所需要的構(gòu)象,。
該研究工作得到中國(guó)科學(xué)院,、科技部重大科學(xué)研究計(jì)劃、國(guó)家自然科學(xué)基金委以及上海市科委的資助,。（生物谷Bioon.com）
生物谷推薦原文出處：
Biochem.J. doi:10.1042/BJ20100474
Post-transfer editing by a eukaryotic leucyl-tRNA synthetase resistant to the broad-spectrum drug AN2690
Xiao-Long Zhou, Min Tan, Meng Wang, Xin Chen and En-Duo Wang1
State Key Laboratory of Molecular Biology and Graduate School of the Chinese Academy of Sciences, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, People's Republic of China
Some aaRSs (aminoacyl-tRNA synthetases) develop editing mechanisms to correct mis-charged tRNA. The CP1 (connective peptide 1) domain of LeuRS (leucyl-tRNA synthetase) contains the editing active site, which is the proven target for the broad-spectrum drug AN2690 (5-fluoro-1,3-dihydro-1-hydroxy-2,1-benzoxaborole). The ESI (eukarya-specific insertion 1) in the CP1 domain of GlLeuRS (Giardia lamblia LeuRS) has been identified. Similar substitution with the ESI from HsLeuRS (Homo sapiens LeuRS) impeded the leucine activation, aminoacylation and post-transfer editing of the enzyme, but had no effect on the editing specificity toward non-specific amino acids. Thr341 in GlLeuRS served as a specificity discriminator, as found in other LeuRS systems, although its substitution with an alanine residue did not destroy Leu-tRNALeu synthesis in vitro and in vivo. The Arg338 was crucial for tRNALeu charging and the Asp440 was crucial for leucine activation and aminoacylation. The post-transfer editing required the CTD (C-terminal domain), Arg338 and Asp440 of GlLeuRS. Interestingly, GlLeuRS was completely resistant to the AN2690, which is an inhibitor of various LeuRSs. The universally conserved aspartate residue in the LeuRS CP1 domains was responsible for the resistance of GlLeuRS and another recently reported AN2690-resistant AaLeuRS (Aquifex aeolicus LeuRS). Our results indicate the functional divergence of some absolutely conserved sites, improve the understanding of the editing function of eukaryotic/archaeal LeuRSs and shed light on the development of a GlLeuRS-specific inhibitor for the treatment of giardiasis.
