中文摘要：

基因的点突变体在其结构和功能研究中发挥非常关键的作用,如何高效、经济地构建基因点突变体是许多分子生物学研究遇到的棘手问题.以PIAS3点突变体的构建为对象,设计了新型的以反向PCR为基础的点突变构建流程,获得的点突变体质粒经测序后均与预期相符,并在293T细胞内得到了正确表达.以上结果表明,该实验设计方案能够高效、方便地用于基因点突变体的构建,为进一步研究它们的分子功能打下了基础.

英文摘要：

Site-directed mutagenesis plays important roles to study protein structure-function relationship and the researchers are always confronted with the problem on how to generate a point mutation of a target gene efficiently.A novel strategy to produce a point mutation was depicted based on inverse PCR with PIAS3 as an example.Firstly,the entire PIAS3 coding sequence was amplified from MCF-7 cDNA and then cloned into the expression vector pXJ40-myc.Two sets of PIAS3 primers with specific mutation sequences were synthesized and then phosphorylated at their 5′ terminus.Inverse PCR was performed with the phosphorylated primers as well as with the plasmid pXJ40myc-PIAS3 as the template.Further,the PCR products were subjected to DpnⅠ treatment,agarose gel purification,self-ligation and transformation into DH5α.Three colonies were randomly selected for DNA sequencing.The expression of both the PIAS3 wide type and the point mutants（PIAS3 K110R and K411,412R） was analyzed by transfection of these plasmids into 293T cells.The result showed that the PIAS3 K110R and K411,412R point mutants were successfully constructed and expressed in mammalian cells,which suggested that the novel inverse PCR stratagy can be applied to construct the point mutants of a target gene efficiently and conveniently.