人线粒体tRNA t^(6)A修饰酶OSGEPL1的功能位点鉴定

Characterization of human mitochondrial tRNA t^(6)A-modifying enzyme OSGEPL1

tRNA t^(6)A是一种进化上保守的转录后修饰,对翻译和蛋白质稳态平衡至关重要,其缺失严重影响细胞生命和高等生物的组织和器官发育.三界生物系统中的tRNA t^(6)A修饰酶随着生物复杂性的增加而进化出多层次的调控机制.人YRDC和OSGEPL1负责线粒体中tRNA t^(6)A的生物合成.YRDC催化L-threonine,HCO_(3)^(-)/CO_(2)和ATP生成TC-AMP中间体,其上的TC-基团由OSGEPL1催化转移至tRNA A37的第6位氮原子上,形成tRNA t^(6)A.本研究分析了OSGEPL1与人线粒体tRNA的相互作用和其t^(6)A催化活性之间的关系.基于OSGEPL1-tRNA复合体预测模型,进一步分析了OSGEPL1的金属离子结合位点、TC-AMP结合位点和tRNA结合位点.研究结果对于理解OSGEPL1-tRNA-TC-AMP复合体的分子识别和催化调控提供了理论见解和实验数据.

tRNA t^(6)A is an evolutionarily conserved post-transcriptional modification that plays a pivotal role in promoting protein translation and maintaining proteostasis.The absence of tRNA t^(6)A gravely affects cellular life and causes abnormal development of tissues and organs of higher eukaryotes.The tRNA t^(6)A-modifying enzymes of the three domains of life have evolved multiple levels of regulation in coping with the increasing biological complexity.Human YRDC and OSGEPL1 cooperatively catalyze the biosynthesis of tRNA t^(6)A in mitochondria.YRDC first utilizes L-threonine,HCO_(3)^(-)/CO_(2)and ATP to generate an intermediate threonylcarbamoyladenylate(TC-AMP);OSGEPL1 catalyzes the transfer of TC-moiety from TC-AMP onto N6 atom of tRNA A37,leading to tRNA t^(6)A.In this study,we characterized the interaction and t^(6)A-catalytic activity between OSGEPL1 and human mitochondrial tRNAs.We constructed an OSGEPL1-tRNA model and tested the effects of mutations of functional sites that are involved in coordination of metal ions and TC-AMP,and in tRNA binding.The results provide insights and experimental data to mechanistic elucidation of the molecular recognition and catalytic regulation of OSGEPL1-tRNA-TC-AMP complex in the future.