原型泡沫病毒Bel1蛋白核定位信号精细定位及相互作用核输入蛋白初探  

Identification of Prototype Foamy Virus Bel1 Nuclear Localization Signal and Its Corresponding Importins

作　　者：马庆林[1] 于淼[1] 罗迪 谈娟[1] 乔文涛[1] 

机构地区：[1]南开大学分子微生物与技术教育部重点实验室南开大学生命科学学院,天津300071

出　　处：《病毒学报》2014年第4期346-352,共7页Chinese Journal of Virology

基　　金：国家自然科学基金(31370182,31070135);教育部新世纪优秀人才支持计划项目(NCET-10-0508)

摘　　要：Bel1是原型泡沫病毒(Prototype foamy virus,PFV)的反式激活因子,在病毒的复制周期中发挥关键作用。研究表明,Bel1含有核定位信号(Nuclear localization signal,NLS),但其精确氨基酸组成尚不明确,介导其入核的核输入蛋白亦未见报道。本研究利用插入Bel1截短片段的EGFP-GST融合表达体系,通过绿色荧光观察其亚细胞定位,首次精确确定Bel1NLS序列为215PRQKRPR221;定点突变明确了K218、R219和R221为Bel1核定位的必需残基,证明Bel1NLS属单分型核定位信号;GST-Pulldown实验显示这段序列可与α核输入蛋白(Importinα/Karyopherin alpha,official symbol:KPNA)KPNA1、KPNA6和KPNA7相互作用,即Bel1可能藉此转运入核。Bel1,a transactivator of prototype foamy virus（PFV）,plays pivotal roles in the replication of PFV.Previous studies have shown that Bel1bears a nuclear localization signal（NLS）,but its amino acid sequence remains unclear and the corresponding importins have not been identified.In this report,we inserted various fragments of Bel1into an EGFP-GST fusion protein and investigated their subcellular localization by fluorescence microscopy.We found that the 215PRQKRPR221 fragment could direct nuclear localization,which accords with the consensus sequence K（K/R）X（K/R）of monopartite NLS.Point mutation experiments revealed that K218,R219,and R221 are essential for the nuclear localization of Bel1.The results of the GST-pulldown showed that the Bel1fragment with residues 215-223,which bears the NLS,interacts with KPNA1,KPNA6,and KPNA7.This result suggests that KPNA1,KPNA6,and KPNA7maybe involved in Bel1nuclear translocation.

关 键 词：Bel1 核定位信号 α核输入蛋白 

分 类 号：R373.9[医药卫生—病原生物学]