嗜酸性乳杆菌MG株S层蛋白的高级结构预测分析及原核表达

Tertiary Structure Prediction and Prokaryotic Expression of S-layer Protein of Lactobacillus acidophilus MG Strain

以嗜酸性乳杆菌MG株slp基因(表达S层蛋白的基因)为材料,应用Genetyx软件推导出其正确的开放阅读框(ORF),并用CPHmodels,Swiss-Model和Swiss-PdbViewer生物软件预测SLP蛋白质的高级结构;此外,构建slp基因的原核表达载体pGEX-slp,经IPTG诱导后,成功表达出重组S层蛋白(S-layer protein,SLP),并进行SDS-PAGE和Western blot鉴定。结果表明,使用3种不同的软件预测SLP蛋白质的高级结构,预测结果具有很高的相似性,其中α螺旋占3.33%,线性结构占45%,无规则卷曲占51.67%,平均亲水值为-0.262,亲水氨基酸比例为59.1%;表达载体pGEX-slp在E.coli BL21中经IPTG诱导成功表达出重组SLP蛋白,其GST融合蛋白的大小约为70ku。本研究结果为进一步以SLP为材料的生物制品的制备和应用开发奠定了基础。

In this study, the ORF of sip gene was demonstrated by Genetyx software and cloned from Lactobacillus acidophilus MG strain genomic DNA. The tertiary structure of SLP protein was predicted by CPH model, Swiss-Model, and Swiss-PdbViewer3. In addition, prokaryotic expression vector pGEX-slp was induced by IPTG,and the recombinant S-layer protein was successfully expressed. The fusion protein was identified by SDS-PAGE and Western blot. The results showed that the structure of the SLP was predicted by using three different types of software, almost as same as the predicted results, the s-helix is 3.33 %, linear structure is 45 %, random coil is 51.67%, and average of hydrophilicity value is --0. 262, the proportion of hydrophilic amino acid is 59.1%. The target protein could be highly expressed in E. coli, and the size of GST fusion protein was about 70 ku. This research was basic for further study on SLP biological products and application development.