人白细胞介素4在大肠杆菌中的优化表达

The optimizing expression of human interleukin 4 in E.coli

目的：通过优化设计利用大肠杆菌表达人白细胞介素４（ＩＬ４） 并提高其表达量。方法：根据原核翻译起始序列的局部二级结构自由能，设计了ＡＵＧ 上下游序列，并在人ＩＬ４ 基因下游插入部分大肠杆菌ＬａｃＺ 序列以提高ｍＲＮＡ 的稳定性。结果：成功地构建了人ＩＬ４ 的高效表达克隆，命名为ｐＬＣＭ１８２ｈＩＬ４ 。ＳＤＳＰＡＧＥ 分析显示所表达的重组ＩＬ４ 蛋白质占细菌总蛋白的３０ ％ 。目的基因下游没有插入ＬａｃＺ序列所构建的表达克隆ｐＣＺＨｈＩＬ４ 在大肠杆菌中的表达量则占细菌总蛋白的２０ ％ 左右。结论：所设计的优化表达方法对人ＩＬ４ 基因的表达是成功的，在细胞因子的工程化表达中，优化设计对基因的表达量至关重要。

Objective:Gene expression of cytokines in E.coli has become a routine method to get recombinant cytokines.The human interleukin 4(hIL 4) was expressed in E.coli at low levels that had not exceeded 10%.It is possible to evaluate its expression level by local sequence design.Methods:In the present study,the region around the start codon was designed based upon free energy of RBS local second structure,and partial sequence of E.coli LacZ gene was inserted in the downstream region to improve the statility of the expressing gene.Thus the constructed expression vector with hIL 4 was very efficient and was terminated pLCM182 hIL4.Results:The expressed hIL 4 was up to 30% of total bacterial protein,and the expression level decreased to 20% if the hIL 4 gene was not followed with that partial LacZ gene.Conclusion:The data showed that the optimized methods adopted was successful in hIL 4 expression and indicated optimizing design would be effective in improving gene expression levels of cytokines.