罗伊氏乳杆菌果聚糖蔗糖酶基因的克隆与表达

Cloning and Expression of Levansucrase Gene from Lactobacillus reuteri

以罗伊氏乳杆菌基因组DNA为模板,采用PCR技术克隆获得果聚糖蔗糖酶基因lev。生物信息学分析表明:该基因全长1 776 bp,编码一个含591个氨基酸残基的多肽。该多肽的预测分子质量为65.47 ku,等电点为4.74,二级结构主要有α-螺旋、β-转角、延伸链和无规则卷曲组成。克隆所得的lev基因与Gen Bank注册的罗伊氏乳杆菌lev基因(注册号:EF534264.1)的核苷酸序列同源性为97.97%。本研究所得lev基因经构建表达载体在大肠杆菌BL21中表达,重组酶具有果聚糖蔗糖酶的活性。

In this work,the levansucrase gene was cloned from total DNA of Lactobacillus reuteri by PCR technique.Bioinformatics sofiwares were used to analysis the DNA and predicted protein sequence.The results showed that this levansucrase gene lev was 1 776 bp in size,coding a polypeptide 591 amino acid residues.The predicted molecular weight of this polypeptide was 65.47 ku,and the theoretical PI was 4.74.The secondary structure of predicted polypeptide contain c-helix,β-turn,extending,and random curling.Results of homology analysis displayed that the nucleotide identity between this lev gene and the one reported in GenBank （accession number EF534264.1） was 97.97%.Based on the expression of the present lev gene in Escherichia coli BL21,results showed that the recombinant enzyme has levansucrase activity.