Identification and functional expression of genes encoding flavonoid O- and C-glycosidases in intestinal bacteria
Identification and functional expression of genes encoding flavonoid O- and C-glycosidases in intestinal bacteria
复制标题
DOI：
10.1111/1462-2920.12864
复制
发表时间：
2016-07-01
影响因子：
5.1
通讯作者：
Blaut, Michael
中科院分区：
文献类型：
--
作者：
Braune, Annett;Engst, Wolfram;Blaut, Michael
肠道细菌在膳食类黄酮的代谢中起着至关重要的作用，从而影响这些化合物在宿主体内的生物活性。肠道毛螺科菌株CG19-1和真细菌纤维素溶剂能够脱糖基化C-和o偶联的类黄酮糖苷。菌株CG19-1在异黄酮c -葡萄糖苷葛根素（大豆苷8- c -葡萄糖苷）存在下生长，诱导两种蛋白（DfgC, DfgD）。编码基因（dfgC, dfgD）在大肠杆菌中的异源表达表明，所得到的细胞提取物没有c -去糖基化活性，但可以裂解黄酮类o -糖苷，如大豆苷元（daidzein 7-O-glucoside）。对重组DfgC和DfgD蛋白进行了纯化，并对其四级结构、底物和辅因子特异性进行了表征。相应基因dfgC、dfgD的产物在大肠杆菌中表达后也能催化大豆苷的o -去糖基化。与相邻基因编码的3个重组蛋白（dfgA、dfgB、dfgE）、DfgC和DfgD结合，催化了黄酮c -葡萄糖苷同荭草苷（木犀草素6- c -葡萄糖苷）和异牡荆素（芹菜素6- c -葡萄糖苷）的脱糖基化。即使是表达5种e.c ullosolvens基因的完整大肠杆菌细胞，也能将这些黄酮c -葡萄糖苷和类黄酮o -葡萄糖苷裂解为相应的苷元。
Gut bacteria play a crucial role in the metabolism of dietary flavonoids and thereby influence the bioactivity of these compounds in the host. The intestinal Lachnospiraceae strain CG19-1 and Eubacterium cellulosolvens are able to deglycosylate C- and O-coupled flavonoid glucosides. Growth of strain CG19-1 in the presence of the isoflavone C-glucoside puerarin (daidzein 8-C-glucoside) led to the induction of two proteins (DfgC, DfgD). Heterologous expression of the encoding genes (dfgC, dfgD) in Escherichia coli revealed no C-deglycosylating activity in the resulting cell extracts but cleavage of flavonoid O-glucosides such as daidzin (daidzein 7-O-glucoside). The recombinant DfgC and DfgD proteins were purified and characterized with respect to their quaternary structure, substrate and cofactor specificity. The products of the corresponding genes (dfgC, dfgD) from E.cellulosolvens also catalysed the O-deglycosylation of daidzin following their expression in E.coli. In combination with three recombinant proteins encoded by adjacent genes in E.cellulosolvens (dfgA, dfgB, dfgE), DfgC and DfgD from E.cellulosolvens catalysed the deglycosylation of the flavone C-glucosides homoorientin (luteolin 6-C-glucoside) and isovitexin (apigenin 6-C-glucoside). Even intact cells of E.coli expressing the five E.cellulosolvens genes cleaved these flavone C-glucosides and, also, flavonoid O-glucosides to the corresponding aglycones.