猪白细胞介素18基因的克隆、表达及生物学活性检测

通过RT-PCR方法直接从猪脾脏淋巴细胞中扩增出猪白细胞介素18(pIL-18)成熟蛋白基因的cDNA, 克隆到pGEM-T载体, 构建重组质粒pGEM-T-IL18, 转化E.coli JM109感受态细胞, 取PCR和酶切鉴定为阳性的重组质粒进行序列测定。测序结果表明, pIL-18成熟蛋白基因核苷酸长度为474 bp, 编码157个氨基酸。将其克隆到表达载体pGEX6P-1中, 构建重组质粒pGEX-IL18, 转化E.coli BL21感受态细胞, 用IPTG诱导表达。重组菌菌体裂解物SDS-PAGE可检测到相对分子质量为45 kD的重组蛋白, 占菌体总蛋白的28%左右, 以包涵体形式存在。对包涵体进行洗涤, 用MTT法测定表明, 重组蛋白能明显刺激猪脾脏T淋巴细胞增殖反应的活性。

Gene Cloning, Expression and Activity Detection of Porcine lnterleukin-18 Mature Protein in Escherichia coli

Porcine interleukin-18 mature protein gene was amplified from porcine spleen cells by RT-PCR. PCR product was cloned into the T vector pGEM-T for sequencing. The nucleotide sequence of this gene was 474 bp. Then, it was subcloned into the prokaryotic expressing plasmid vector pGEX6P-1 and transformed into host E. coli strain BL21 for expression. The expression of pIL-18 mature protein gene was identified by SDS-PAGE .The expression product was fusion protein with molecular weight of 45 kD and the percentage of expression protein in E. coil protein was 28%. The protein was purified by washing of inclusion bodies and the activity was measured by methyl thiazolyl tetrazolium (MTT).