八肋游仆虫氨酰-tRNA合成酶基因序列分析

Sequence Analysis of the Aminoacyl-tRNA Synthetase Genes of Euplotes octocarinatus

氨酰-tRNA合成酶(aminoacyl-tRNA synthetase,aaRS)是蛋白质生物合成中的关键酶,能够催化特定的氨基酸和相应tRNA结合。为了研究八肋游仆虫氨酰-tRNA合成酶(Euplotes octocarinatus aminoacyl-tRNA synthetase,EoaaRS)基因的种类、数目、结构及起源,本研究利用生物信息学方法,对八肋游仆虫大核基因组编码的aaRS进行了系统分析。结果表明,八肋游仆虫大核基因组共包含45个aaRS基因,可编码20种不同的aaRS蛋白。其中,Eo GlnRS和Eo AlaRS仅由1个基因编码,其余EoaaRS均由多个基因编码。亚细胞定位分析显示,仅8个EoaaRS具有线粒体导肽,对应于6种EoaaRS。此外,基于核酸序列分析显示,多个EoaaRS在翻译过程中需要发生编程性核糖体移码,才能形成结构完整的蛋白质产物。结构域分析表明,部分EoaaRS存在特殊结构域,暗示其可能具有氨酰化以外的新功能。进化分析揭示,2个Eo GlyRS起源于古菌,而2个Eo LysRS起源于细菌。本研究为后续探讨低等真核生物aaRS的结构与功能奠定了基础。

Aminoacyl-tRNA synthetases （aaRSs） are critical enzymes in protein synthesis, which attach the specific amino acids to their cognate tRNAs. For further investigation of the type, number, structure and origin of aminoacyl-tRNA synthetase genes from Euplotes octocarinatus （EoaaRS）, systematic analysis by bioinformatics was performed to study the aaRS encoded by E. octocarinatus macronuclear genome. Forty-five EoaaRS genes encoding 20 different proteins of EoaaRSs were identified. Most EoaaRSs were encoded by more than one gene except EoGlnRS and EoAlaRS. Subcellular localization analysis showed that only 8 EoaaRSs encoding 6 EoaaRSs owned mitochondrial targeting peptides. In addition, nucleic acid-based analysis revealed that several EoaaRSs require a programmed ribosomal frameshifting （PRF） to produce complete protein products. The domain analysis demonstrated that some EoaaRSs contained special domains, which suggested that they might perform new functions other than aminoacylation. Evolutionary analysis revealed that two different EoGIyRS and two different EoLysRS genes were originated from archaea and bacteria, respectively. This study provide a foundation for future study on the structure and function of the aaRS in lower eukaryotes.