L1.LtrB内含子编码蛋白反转录结构域关键催化位点分析及功能验证  

Key catalytic sites in the reverse transcription domain of Ll.LtrB intron encoded protein

作　　者：陈相好 张峥嵘 刘芳 陈峥宏 洪伟[4] 綦廷娜 谷俊莹 崔古贞 Xianghao Chen;Zhengrong Zhang;Fang Liu;Zhenghong Chen;Wei Hong;Tingna Qi;Junying Gu;Guzhen Cui(School of Basic Medical Science,Guizhou Medical University,Guiyang 550025,Guizhou Province,China;School of Clinical Laboratory Science,Guizhou Medical University,Guiyang 550004,Guizhou Province,China;Key Laboratory of Medical Microbiology and Parasitology of Education Department of Guizhou,Guiyang 550025,Guizhou Province,China;Key Laboratory of Molecular Biology,Guizhou Medical University,Guiyang 550004,Guizhou Province,China;Affiliated Hospital of Guizhou Medical University,Guiyang 550004,Guizhou Province,China)

机构地区：[1]贵州医科大学基础医学院,贵州贵阳550025 [2]贵州医科大学医学检验学院,贵州贵阳550004 [3]贵州省普通高等学校病原生物学特色重点实验室,贵州贵阳550025 [4]贵州医科大学分子生物学重点实验室,贵州贵阳550004 [5]贵州医科大学附属医院,贵州贵阳550004

出　　处：《微生物学报》2019年第12期2357-2366,共10页Acta Microbiologica Sinica

基　　金：国家自然科学基金(31760318,31500078,31560318,31601012);贵州省科技计划项目(黔科合基础[2018]1132,[2019]1441);贵州省教育厅自然科学研究项目(黔教合KY字[2014]216);贵州省研究生科研基金立项项目(11348)~~

摘　　要：【目的】筛选影响Ll.LtrB内含子编码蛋白(Intron encoded protein,IEP)反转录功能的关键催化位点,并获得无反转录活性的IEP突变体。【方法】首先,利用NCBI数据库,通过序列比对及同源建模方法筛选影响IEP反转录功能的关键氨基酸催化位点;然后,对筛选获得的关键催化位点进行定点突变,同时以Targetron载体为模板,构建无反转录功能的突变型Targetron打靶系统;最后,以大肠杆菌lacZ基因为例,体内验证IEP突变体的功能及其对Ⅱ型内含子"归巢"效率的影响。【结果】筛选到C164和G214两个位点是影响内含子编码蛋白反转录功能的关键氨基酸残基,并获得C164K和G214W两个突变体。体内功能分析表明,此两个位点突变完全失活了Ⅱ型内含子的"归巢"功能。【结论】筛选并获得了失活反转录功能的Ll.LtrB内含子编码蛋白突变体,为深入研究Ⅱ型内含子的结构和"归巢"机理奠定了基础。[Objective] To screen the key catalytic sites that affect the reverse transcription function of intron-encoded protein(IEP) from Ll.LtrB, and to obtain the IEP mutant without reverse transcription activity. [Methods] The key catalytic sites affecting the reverse transcription of IEP were screened by sequence alignment and homology modeling methods. Then, the screened key catalytic sites were subjected to site-directed mutagenesis. The mutated IEP was combined with the Targetron vector to construct the mutated Targetron targeting system without reverse transcription function. Finally, the function of mutant IEP was verified by using the lacZ gene in Escherichia coli. [Results] The sites C164 and G214 of IEP were screened and mutated, completely inactivated the "retrohoming" function in vivo. [Conclusion] The IEP mutants of Ll.LtrB obtained in our study laid a solid foundation for further research on the structure and mechanism of group Ⅱ intron.

关 键 词：Ll.LtrB Ⅱ型内含子 内含子编码蛋白 反转录 Targetron 

分 类 号：G76[文化科学—特殊教育学]