一种新型β-葡萄糖苷酶基因的分析

Analysis of a novel β-glucosidase gene

宏基因组文库技术已经成为开发未知功能基因及其编码产物的有效途径。本研究采用β-葡萄糖苷酶的活性筛选策略,对所构建的土壤宏基因组文库进行筛选,得到了一个表达β-葡萄糖苷酶活性的阳性克隆。生物信息学分析表明该克隆所包含的外源DNA片断编码一个由151个氨基酸编码组成的多肽。BLASTx软件分析可能的ORF和GenBank数据库中的基因在DNA水平上没有任何相似性;在氨基酸水平上与一种来自于糖基水解酶蛋白家族4的β-葡萄糖苷酶的相似性为56%,同源性为41%。初步的酶学数据表明目标ORF是一种编码β-葡萄糖苷酶的新型基因。本研究工作对于深入挖掘土壤未培养微生物的β-葡萄糖苷酶基因资源具有重要实践意义。

The metagenomic library screening approach has broadened the field of enzymology, leading to the identification of a wider range of natu- ral biocatalysts. Based on constructing a metagenomie library from soil, a possible positive β-glucosidase was cloned using enzyme-activity screening strategy. The bio-informatics analysis indicated that this clone foreign DNA fragment contained a possible integrated ORF which coded a peptide of 151 amino acids. The integrated ORF did not share homology with any other known genes at DNA level according to the BLASTx program. Amino acid sequence comparison revealed that the deduced pepfide had some similarities with a β-glucosidase from glycoside hydrolase family 4 （41% identical and 56% similar）. The bio-informatics analysis of BgllE has enlarged our understanding of the novel enzymes that can be isolated from the soil metagenome.