pur操纵子的启动子部分点突变对肌苷合成的影响

Effect of Point Mutation Existing in Promoter of pur Operon on Inosine Synthesis

以lacZ作为报告基因,对野生菌、肌苷低产菌和肌苷生产菌分别构建了研究型质粒pYH1206、pYH1618和pYH1620,并在大肠杆菌中表达,以研究pur操纵子与其阻遏蛋白PurR的相互作用对肌苷合成的影响。lacZ表达β-半乳糖苷酶相对活性的测定结果和阻遏蛋白PurR的序列分析表明,肌苷生产菌中pur操纵子的启动子部分-272位点处的突变是肌苷高产的主要原因。

In order to study the effect of the interaction between pur operon and purine repressor PurR on inosine synthesis, study-type plasmids pYHI206, pYHI618 and pYH1620 were constructed using lacZ as a report gene for a wildtype strain, a low-yield inosine-producing strain and an inosine-producing strain, respectively. Then lac Z gene encoding β-galactosidase on the plasmids were expressed in E.coli. Results of relative β-galactosidase activity and nucleotide sequence analysis of PurR showed that a point mutation occurred at - 272 nucleotide in purO promotor of inosine-producing strain was the primary cause for high inosine yield.