tRNA t6A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 t6A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 t6A的生物合成.YRDC催化L-threonine,HCO3-/CO2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 t6A.本研究分析了 O SGEPL1与人线粒体tRNA的相互作用和其t6A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.
Characterization of human mitochondrial tRNA t6A-modifying enzyme OSGEPL1
tRNA t6A is an evolutionarily conserved post-transcriptional modification that plays a pivotal role in promoting protein translation and maintaining proteostasis.The absence of tRNA t6A gravely affects cellular life and causes abnormal development of tissues and organs of higher eukaryotes.The tRNA t6A-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 t6A in mitochondria.YRDC first utilizes L-threonine,HCO3-/CO2 and ATP to generate an intermediate threonylcarbamoyl-adenylate(TC-AMP);OSGEPL1 catalyzes the transfer of TC-moiety from TC-AMP onto N6 atom of tRNA A37,leading to tRNA t6A.In this study,we characterized the interaction and t6A-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.
tRNA modification and regulationN6-threonylcarbamoyladenosineOSGEPL1-tRNAstructure-function relationship
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