霍乱毒素A基因内部翻译调控元件具有翻译起始功能  

Translation Initiation Function of the Regulation Element in the Operon of Cholera Toxin A

作　　者：曹诚[1] 李平[1] 李杰之[1] 石成华[1] 马清钧[1] 

机构地区：[1]军事医学科学院生物工程研究所,北京100850

出　　处：《Acta Genetica Sinica》2000年第7期654-657,共4页

基　　金：北京市自然科学基金!5992014

摘　　要：通过大肠杆菌体外转录－体外翻译系统，证明霍乱毒素A基因内部的翻译调控元件具有翻译起始功能，且其翻译起始效率较ctxA基因高得多．当ctxA的起始密码突变时，从该元件起始的翻译效率下降，说明基因内翻译起始效率受ctxA翻译起始的调控。结果进一步证实了霍乱毒素A、B亚基比例表达调控的翻译弱化－翻译偶联机理。To demonstrate that there existed translation coupling between cholera toxin A subunit gene and B subunit gene, and give the answer why the expression level of B gene is five times more than that of A gene, α report system for the investigation of translation coupling was constructed by using lacZ gene as reporter. Frame-shift mutation was introduced near the C terminal of ctxA gene, and the ribosome would read through its normal stop codon. The report plasmid was constructed and it was found that the expression level of lacZ gene decreased five times after the frame-shift mutation. The translation of cholera toxin B subunit gene was translational coupled with A subunit gene, and was responsible for the differential expression level of the two genes.

关 键 词：霍乱毒素 操纵子 翻译调控 体外翻译 A亚基 

分 类 号：Q756[生物学—分子生物学] R516.5[医药卫生—内科学]