Shen Ping, Niu Gang, Yao Minghui, Wang Haoyue, Fei Jian
Model Organism Research Center and Laboratory of Molecular Cell Biology/Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
J Biochem. 2007 Jul;142(1):25-31. doi: 10.1093/jb/mvm098. Epub 2007 Apr 24.
The human cytomegalovirus major immediate early enhancer/promoter (HCMV MIEP), extending from -588 to +1 relative to the transcription start site, contains a series of reiterated cis-acting elements, such as 19-bp repeats, which occur four times in the enhancer/promoter region. However, it is still not clear whether these elements repeat just for backing up or they really execute various indispensable functions. We show here that these reiterated elements are functionally different from each other through serial deletion mutation and site-directed mutation. In addition, we also found that the CG-reverse in the first 19-bp repeat could improve the transcription activity of MIEP in HeLa cells and impair the protein-binding capacity in the EMSA assay. The expression feature of this mutated MIEP in transgenic mice further confirmed its stronger and more universal transcription activity in vivo.
人类巨细胞病毒主要立即早期增强子/启动子（HCMV MIEP），相对于转录起始位点从-588延伸至+1，包含一系列重复的顺式作用元件，如19bp重复序列，其在增强子/启动子区域出现四次。然而，这些元件是仅仅为了备份而重复，还是真的执行各种不可或缺的功能，目前仍不清楚。我们在此表明，通过系列缺失突变和定点突变，这些重复元件在功能上彼此不同。此外，我们还发现，第一个19bp重复序列中的CG反向可提高MIEP在HeLa细胞中的转录活性，并在电泳迁移率变动分析（EMSA）中损害蛋白质结合能力。这种突变的MIEP在转基因小鼠中的表达特征进一步证实了其在体内更强且更普遍的转录活性。
