牛凝乳酶原基因在大肠杆菌中表达调控的研究  

Regulation of the Expression of Calf Prochymosin Gene in Escherichia coli

作　　者：王革[1] 刘年娟 杨开宇[1] 

机构地区：[1]中国科学院微生物研究所,北京100080

出　　处：《生物工程学报》1994年第2期162-167,共6页Chinese Journal of Biotechnology

基　　金：为863生物技术领域支持项目

摘　　要：Shine-Dalgarno序列与起始密码子之间的距离与组成对凝乳酸原基因表达有明显的影响,可导致其表达水平有15倍之差。SD序列至ATG之间为15bp不利于表达,表达质粒中SD-ATG在7-11bP之间都有可能获得高效表达;但决定因素不是简单的长度,而是RBS附近可能的二级结构即△G的大小、SD序列及ATG中参与配对的碱基数目。将pTLC23中凝乳酶原cDNA3＇端非翻译区插入终止密码子TGA与转录终止子rrnBT_1T_2之间适当位置可提高凝乳酶原基因的表达,这可能是因为这段序列能形成由53个碱基对和8个碱基组成的稳定的mRNA二级结构,起到转录终止子的作用,而一般认为串联终止子对终止转录更为有效。The distance and the composition between the Shine-Dalgarno(SD)sequence and the start codon have, profound effect on the expression of prochymosin gene causing a 15fold difference. Fifteen bp span between SD sequence and ATG are unfavourable for gene expression. The plasmids with the length of SD-ATG ranging from 7 -11bp tend to be expressed at higher level,however,the determinat is the potential secondary structure of the ribosome binding site,the AG?the number of the bases of SD and ATG involved in base-pairing rather than simply the distance of SD-ATG. The insertion of the 3'-untranslated region of prochymosin cDNA from pTLC23 at proper position between termination codon TGA and terminator rrnBT1T2 was capable of enhancing the expression of prochymosin gene. It is postulated that the sequence of the insert has the potential to form a stable mRNA secondary structure with a 53 bp stem and a 8base loop,which may act as a terminator. Tandem terminators have been considered more efficient in terminating transcription than a single terminator.

关 键 词：凝乳酶原 基因表达 大肠杆菌 调控 

分 类 号：Q78[生物学—分子生物学]