Cloning of two cellobiohydrolase genes from <Emphasis Type="Italic">Trichoderma</Emphasis><Emphasis Type="Italic">viride</Emphasis> and heterogenous expression in yeast <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> |
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Authors: | Jinzhu Song Beidong Liu Zhihua Liu Qian Yang |
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Institution: | 1.Department of Life Science and Engineering,Harbin Institute of Technology,Harbin,China |
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Abstract: | Cellobiohydrolase genes cbhI and cbhII were isolated from Trichoderma viride AS3.3711 and T. viride CICC 13038, respectively, using RT-PCR technique. The cbhI gene from T. viride AS3.3711 contains 1,542 nucleotides and encodes a 514-amino acid protein with a molecular weight of approximately 53.96 kDa.
The cbhII gene from T. viride CICC 13038 was 1,413 bp in length encoding 471 amino acid residues with a molecular weight of approximately 49.55 kDa. The
CBHI protein showed high homology with enzymes belonging to glycoside hydrolase family 7 and CBHII is a member of Glycoside
hydrolase family 6. CBHI and CBHII play a role in the conversion of cellulose to glucose by cutting the disaccharide cellobiose
from the non-reducing end of the cellulose polymer chain. The two cellobiohydrolase (CBHI, CBHII) genes were successfully
expressed in Saccharomyces cerevisiae H158. Maximal activities of transformants Sc-cbhI and Sc-cbhII were 0.03 and 0.089 units ml−1 under galactose induction, respectively. The optimal temperatures of the recombinant enzymes (CBHI, CBHII) were 60 and 70°C,
respectively. The optimal pHs of recombinant enzymes CBHI and CBHII were at pH 5.8 and 5.0, respectively. |
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