Vigal T, Martin J F, Gil J A
Area de Microbiología, Facultad de Biología, Universidad de León, Spain.
FEMS Microbiol Lett. 1994 May 15;118(3):259-63. doi: 10.1111/j.1574-6968.1994.tb06838.x.
The amy gene of Streptomyces griseus was not expressed in Escherichia coli cells due to the lack of recognition of the amy promoter by the E. coli RNA polymerase, as confirmed by using promoter-probe vectors. The expression of the amy gene in E. coli was detected only when the promoter-less gene was placed under the control of the lacZ promoter and was dependent on the level of IPTG added to the medium. The extracellular alpha-amylase detected in the culture broth seems to be released by cellular lysis. When the amy gene lacking both leader peptide and promoter was transcribed from the lacZ promoter, no alpha-amylase activity was detected but larger E. coli cells and inclusion bodies were observed.
通过使用启动子探针载体证实，由于大肠杆菌RNA聚合酶无法识别灰色链霉菌的淀粉酶基因（amy基因）的启动子，该基因在大肠杆菌细胞中不表达。仅当无启动子的基因置于lacZ启动子的控制下且依赖于添加到培养基中的异丙基-β-D-硫代半乳糖苷（IPTG）水平时，才能检测到amy基因在大肠杆菌中的表达。在培养液中检测到的细胞外α-淀粉酶似乎是通过细胞裂解释放出来的。当从lacZ启动子转录缺乏前导肽和启动子的amy基因时，未检测到α-淀粉酶活性，但观察到更大的大肠杆菌细胞和包涵体。
