【摘要】 TET(ten-eleven translocation)家族蛋白能够介导DNA的5-甲基胞嘧啶(5-methylcytosine,5m C)的氧化,产生5-羟甲基胞嘧啶(5-hydroxymethylcytosine,5hm C)。通过TET蛋白的催化,可以诱导特定靶基因的启动子区域Cp G岛的去甲基化,从而激活基因的转录。TET1蛋白是一个拥有2039个氨基酸的DNA去甲基化酶,通过预测,TET1拥有18个核定位信号(nuclear localization signals,NLSs),其中13个为单分型NLS,5个为双分型NLS。本文利用绿色荧光蛋白和各种突变体,首次确定了小鼠TET1蛋白的2个NLSs,分别存在于CXXC结构域和催化结构域,而且这2个NLSs对全长TET1的和定位都是必需的。我们的研究对深入理解TET1的蛋白结构与功能研究具有重要意义。更多还原

【Abstract】 The ten-eleven translocation( Tet) proteins are DNA demethylases recently identified to catalyze the conversion of 5-methylcytosine( 5mC) of DNA to 5-hydroxymethylcytosine( 5hmC). This conversion induces demethylation of Cp G island in target gene promoters and subsequently transcriptional activation. The TET1 protein is predicted to possess eighteen nuclear localization signals( NLSs),thirteen monopartite NLSs and five bipartite NLSs. In this report,we used a series of green fluorescent protein-tagged mutants to identify two NLSs of mouse TET1,one NLS( 603KKRK606) is embedded in the CXXC domain,which has a preference for binding Cp G-rich DNA and a high affinity for binding to nonmethylated Cp G sequences,while the other( 1720RKRR1723) locates in the catalytic domain. We further demonstrated that both NLSs are essential for nuclear localization of the full-length TET1. Our results are benificial for fully understanding structure and function of TET1.更多还原