Ligilactobacillus sp.BD7642关键胆盐水解酶的发掘

Discovery of core bile salt hydrolase in Ligilactobacillus sp.BD7642

随着人们生活水平的逐步提高,肥胖症的发生率在迅速升高。乳杆菌作为优秀的益生菌库,其对肥胖症具有很好的预防治疗效果,其中胆盐水解酶可能发挥着关键作用。胆盐水解酶对胆盐的降解具有特异性,对不同来源的胆盐水解酶的发掘及解析研究显得至关重要。该研究发现的一株Ligilactobacillus sp.BD7642具有很高的胆盐水解酶活性,并对这一菌株来源的胆盐水解酶进行发掘。通过牛磺脱氧胆酸钠平板的方法筛选发现Ligilactobacillus sp.BD7642具有高胆盐水解酶活性;利用HPLC分析BD7642对6种胆盐的降解特异性,发现其对牛磺酸胆盐具有偏好性;对BD7642的基因组进行分析发现3个注释为胆盐水解酶相关基因g1210、g1294、g1443,将这3个基因在大肠杆菌中异源表达,发现表达的3个蛋白都具有胆盐水解酶活性,其中g1294的胆盐水解酶活性最强;分子对接发现,g1294对牛磺酸的连接位点更紧密,这对g1294的高酶活力做出了一定的解释,也为后续合成生物学、菌株的人工改造提供新的思路和素材。

As people′s living standards improved gradually,the incidence of obesity is increasing rapidly.Lactobacillus is an excellent probiotic library and it has been found to have a preventive and therapeutic effect on obesity,and bile salt hydrolase(BSH)may play a key role.The specific degradation of bile salts by BSH makes the exploration and analysis of BSH from different strains particularly important.In this study,a strain of Ligilactobacillus sp.BD7642 with high BSH activity was found.This study explored the BSH from this strain.Ligilactobacillus sp.BD7642 with high BSH activity was screened by taurodeoxycholic acid sodium plate method.HPLC analyzed that Ligilactobacillus sp.BD7642 had a preference for taurocholic acid among 6 kinds of bile salts.Genome analysis of Ligilactobacillus sp.BD7642 revealed 3 genes(g1210,g1294,g1443)annotated as related to BSH,these 3 genes were heterologously expressed in E.coli BL21(DE3)and all of three expressed proteins had BSH activity,with g1294 having the highest BSH activity.Molecular docking showed that g1294 had a tighter binding site for taurine than other proteins,which interpreted its high enzyme activity and also provided new ideas and materials for future synthetic biology and artificial modification of strains.