家蚕天蚕素cDNA原核表达及抗菌活性检测

采用RT-PCR方法从家蚕Bombyx mori新疆品种新蚕三号组织中扩增天蚕素cDNA片段，回收并克隆至Pmd18-T载体，进行序列分析。基因序列分析结果与已发表的天蚕素B的序列同源性为98%，表明所克隆的新疆家蚕天蚕素cDNA为独特的cDNA片段。将天蚕素基因与Pgex-4T-1融合表达载体中的谷胱甘肽转移酶基因融合,在大肠杆菌中表达, 结果表明经IPTG 诱导30 min后，pGEX-4T-1/天蚕素转化后的大肠杆菌生长明显受到抑制；当诱导210 min 后，大肠杆菌数量又开始增加，逐渐恢复至正常水平。说明天蚕素与谷胱甘肽转移酶基因融合表达后，在IPTG存在的短时间内仍然对原核细胞有较强的抗菌抑杀作用。

Prokaryotic expression of cecropin gene isolated from the silkworm Bombyx mori Xinjiang race and antibacterial activity of fusion cecropin

In order to clone the cecropin gene from the silkworm Bombyx mori(Xinjiang race) into a T-vector, designed primer was used to amplify 350 bp cecropin cDNA fragment with RT-PCR. Cecropin sequence analysis indicates that the special cecropin fragment of the silkworm Xinjiang race contains entire coding region with 98% identity compared with other reported Bombyx mori cecropin B. The cecropin gene was cloned into expression plasmid pGEX-4T-1 and expressed as fusion protein in Escherichia coli BL21. The results showed that the growth of E.coli contained pGEX-4T-1/cecropin was restrained 30 minutes after adding IPTG and the amount of E.coli began to recover 210 minutes after IPTG induction. This result reveals that the fusion protein has antibacterial activity.