康宁木霉K801纤维素酶cbh2基因的克隆及序列分析

CLONE AND SEQUENCE ANALYSIS OF THE CELLOBIOHYDROLASE II GENE (CBH2) FROM TRICHODERMA KONINGII K801

通过聚合酶链式反应（PCR）技术扩增得到纤维素高产菌株康宁木霉Trichoderma k■ningii K801纤维二糖水解酶（CBHII）基因全序列，并克隆到pGEM-Teasy Vector。序列分析表明，所克隆的cbh2基因长1611bp，包含了纤维二糖水解酶基因的完整编码区序列，并含有三个真核生物典型的内含子序列，其中四个外显子序列共同编码一个471aa的蛋白质。该序列是国内首次克隆得到的cbh2编码区全序列，与国外报道的T. reesei已知序列的同源性达到99.89％,只有两个碱基差别，而推测的氨基酸序列只有一个位置疏水性氨基酸之间发生替代，在推测的氨基酸序列上发现3个潜在的N-糖基化位点。

The cellobiohydrolase II gene, cbh2 was amplified by polymerase chain reaction(PCR) from an enhanced cellulase-producing strain, Trichoderma k?ningii K, and then was cloned to T-easy vector. Sequence comparisons show that cbh2 of T. k■ningii is identical to that of T. reesei with the exception of 2 bp in the coding region, which cause an amino acid substituted in the mature CBHII protein. The similarity values between CBHII gene of T. k?ningii and reported cbh2 gene of Trichoderma reesei is 99.89%. The cbh2 gene of T. k?ningii is 1611bp long, and the coding region is interrupted by three short introns. The derived CBHII protein sequence is 471 amino acids long and three putative N-glycosylation sites is found.