人尿激酶原在大肠杆菌中表达的研究

用限制性内切酶将人尿激酶原cDNA酶切成一系列基因片段，并分别在大肠杆菌中表达。发现其中1个富含大肠杆菌稀有密码子AGG(精氨酸)的片段表达量低，成为人尿激酶原cDNA在E.coli中高效表达的限制因素。将富含AGG(精氨酸)的片段在E.coliBL21-CodonPlus^TM-RIL中表达，通过该菌株引入dnaY基因(即tRNA_agg/aga(Arg))使该片段的表达量提高了10倍。最后用同样的方法提高全长人尿激酶原cDNA在大肠杆菌中的表达量，使其表达量达到全菌蛋白的5%。

Studies on Expression of Human Pro-urokinase in Eschevichia coli

Studies were made on the enhancement of expression of human pro-Urokinase(Pro-UK) cDNA in Eschevichia coli. By means of PCR, the signal peptide DNA sequence was deleted. For study of the limited factors in expression of pro-Urokinase, the pro-UK gene was divided into three fragments, and they were expressed in E.coli BL21(DE3), The expression of middle fragment is very low, because there are several rare codon AGG(Arg) in it. Using a new bacteria E.coli BL21-CodonPlus^TM-RIL to introduce dnaY gene coding tRNA_agg/aga(Arg) to recognize the rare codon AGG, the expression level of the middle fragment was enhanced to 10%～20% of total cell protein and the expression of the intact pro-UK was enhanced to 5% by more than 10 folds.