Expression of talaromyces emersonii cellobiohydrolase cel7a in saccharomyces cerevisiae and rational mutagenesis to improve its thermostability and activity
Voutilainen, S. P. Murray, P. G. Tuohy, M. G. Koivula, A.
Voutilainen, S. P.
Murray, P. G.
Tuohy, M. G.
Koivula, A.
Repository DOI
Publication Date
2009-12-01
Keywords
cellulase, disulphide bridge, saccharomyces cerevisiae, site-directed mutagenesis, talaromyces emersonii, trichoderma-reesei cellobiohydrolase, substrate-binding, phanerochaete-chrysosporium, family-7 cellobiohydrolases, cellulose hydrolysis, crystal-structures, protein stability, processive action, cloning, gene
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Article
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Citation
Voutilainen, S. P. Murray, P. G.; Tuohy, M. G.; Koivula, A. (2009). Expression of talaromyces emersonii cellobiohydrolase cel7a in saccharomyces cerevisiae and rational mutagenesis to improve its thermostability and activity. Protein Engineering Design and Selection 23 (2), 69-79
Abstract
We report here a successful expression of a single-module GH-7 family cellobiohydrolase Cel7A from a thermophilic fungus Talaromyces emersonii (Te Cel7A) in Saccharomyces cerevisiae. The heterologous expression system allowed structure-guided protein engineering to improve the thermostability and activity of Te Cel7A. Altogether six different mutants aimed at introducing additional disulphide bridges to the catalytic module of Te Cel7A were designed. These included addition of five individual S-S bridges in or between the loops extending from the beta-sandwich fold, and located either near the active site tunnel or forming the tunnel in Te Cel7A. A triple mutant containing the three best S-S mutations was also engineered. Three out of five single S-S mutants all had clearly improved thermostability which was also reflected as improved Avicel hydrolysis efficiency at 75 degrees C. The best mutant was the triple mutant whose unfolding temperature was improved by 9 degrees C leading to efficient microcrystalline cellulose hydrolysis at 80 degrees C. All the additional S-S bonds contributed mainly to the thermostability of the Te Cel7A, but one of the mutants (N54C/P191C) also showed, somewhat surprisingly, improved activity even at room temperature.
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Publisher
Oxford University Press (OUP)
Publisher DOI
10.1093/protein/gzp072
Rights
Attribution-NonCommercial-NoDerivs 3.0 Ireland