长梗木霉纤维素酶基因的克隆及序列分析

Cloning and Sequence Analysis of Cellulase Genes from Trichoderma longibrachiatum

从富含纤维素环境筛选获得一株纤维素降解菌株FU05,通过形态学特征及ITS序列分析确定其为长梗木霉(Trichoderma longibrachiatum)。PCR扩增获得该菌株的bgl2、cbh2和eg1。序列分析表明,这3种纤维素酶基因与GenBank上其他木霉同种纤维素酶基因具有较高同源性:bgl2基因与里氏木霉bgl2基因(AB003110)同源性达91%;cbh2基因与康宁木霉cbh2基因(DQ504304)同源性达99%;eg1基因与长梗木霉eg1基因(X60652)同源性达95%。3种纤维素酶基因编码的相应氨基酸序列与其他木霉纤维素酶的氨基酸序列相似性也非常高。对上述纤维素酶基因编码的相应蛋白进行PROSITE motif search,对其N端糖基化位点、纤维素结合区、糖基水解酶家族特征结构区等进行了定位。

Strain FU05 with cellulose-degrading activity was isolated from cellulose-rich environment and identified as Trichoderma longibrachiatum through morphology characteristics and ITS sequence analysis. The cellulase genes bgl2, cbh2 and eg1 were cloned by PCR. By conducting sequence alignment analysis with the reported data it was found that the homology of same cellulase genes between strain FU05 and other Trichoderma were： 91% to bgl2 （AB003110） from Trichoderma reesei; 99% to cbh2 （DQ504304） from Trichoderma koninqii and 95% to eg1 （X60652） from Trichoderma longibrachiatum. Furthermore, the corresponding amino acid sequences were also quite similar. By means of PROSITE motif search, the locations of N-glycosylation site, cellulose-binding domain and conserved domains of glycosyl hydrolases family in the corresponding protein were confirmed.