鼠李糖乳杆菌JAAS8胞外多糖生物合成基因的克隆及生物信息学分析

Cloning and Bioinformatic Analysis of Exopolysaccharide Biosynthesis Genes from Lactobacillus rhamnosus JAAS8

根据已知乳杆菌胞外多糖生物合成基因的同源性,利用其保守区设计引物,扩增出鼠李糖乳杆菌JAAS8磷蛋白磷酸酶基因(wzb)序列,并通过染色体步移法克隆了鼠李糖乳杆菌JAAS8参与胞外多糖生物合成基因簇全部序列(19.7kb),利用生物信息学方法预测了基因簇16个阅读框的结构和功能。结果表明,该序列与已报道的乳杆菌胞外多糖生物合成基因具有高度同源性。welF、welG、welH、welI、welJ和welE为合成寡糖重复单元的糖基转移酶基因。rmlA、rmlB和rmlC基因与dTDP-L-鼠李糖前体的生物合成密切相关。wzd、wze、wzy、wzx、wzr和wzb基因预测蛋白主要参与胞外多糖合成过程中多糖链长检测、聚合和输出。

The exopolysaccharide（EPS） biosynthetic genes of Lactobacillus rhamnosus JAAS8 were located on the chromosome in a 19.7 kb region consisting of 16 open reading frames.GenBank database searching showed that the predicted protein products of the gene cluster from L.rhamnosus JAAS8 had the highest identity with the EPS biosynthetic genes of Lactobacillus.The central portion of the locus was occupied by six genes（welF,welG,welH,welI,welJ and welE） encoding potential glycosyltransferases.Three genes（rmlA,rmlB and rmlC） involved in the biosynthesis of the sugar nucleotide precursor dTDP-L-rhamnose were identified in the EPS biosynthesis locus.The predicted amino acid sequences from six genes（wzd,wze,wzy,wzx,wzr,and wzb） have the most resemble proteins involved in putative polysaccharide chain length determination,polymerization and export.