大肠杆菌caiAB基因的克隆与表达

Cloning and Expression of E . coli caiAB Genes

从E.coli MC4100菌株的染色体DNA中利用鸟枪法克隆含编码巴豆甜菜碱还原酶和L-肉碱脱水酶的caiAB基因片段,并经序列分析验证。由重组质粒pZJD-1480亚克隆得到pT7-A以及pT7-B重组表达质粒,后者转入E.coliBL21（DE3）菌株中,经异丙基硫代半乳糖苷（IPT）诱导,在聚丙烯酰胺凝胶电泳（SDS-PAGE）上分子质量为40ku附近可见明显的表达蛋白带。

The caiAB genes for crotonobetaine reductase and carnitine dehydrase were cloned into pUC18 from the chromosomal DNA of E. coli MC4100 strain by shot-gun approach and have been verified by sequence analysis. The target plasmid was named as pZJD-1480 and subcloned to form a transcription plasmid pT7-A and pT7-B. After its transformation into BL21(DE3) strain and induction by IPTG, the recombinant strain containing pT7-A and pT7-B expressed two protein bands on SDS-PAGE, whose molecular weight were both around 40ku.