Mutation of the Xylanase regulator 1 causes a glucose blind hydrolase expressing phenotype in industrially used Trichoderma strains

Biotechnology for Biofuels

Christian Derntl²  Loreta Gudynaite-Savitch¹  Sophie Calixte¹  Theresa White¹  Robert L Mach²  Astrid R Mach-Aigner² 

[1] Iogen Corp., 310 Hunt Club Rd., Ottawa, ON, K1V 1C1, Canada

[2] Department for Biotechnology and Microbiology, Institute of Chemical Engineering, Vienna University of Technology, Gumpendorfer Str. 1a, Wien, A-1060, Austria

关键词: Glucose response domain;    Xylanase regulator 1 (Xyr1);    Biofuel;    Inducer-independent enzyme production;    Cellulases and hemicellulases;    Hypocrea jecorina;    Trichoderma reesei;   

Others  :  798076
DOI  :  10.1186/1754-6834-6-62

 received in 2012-12-13, accepted in 2013-04-23,  发布年份 2013

【 摘 要 】

Background

Trichoderma reesei is an organism involved in degradation of (hemi)cellulosic biomass. Consequently, the corresponding enzymes are commonly used in different types of industries, and recently gained considerable importance for production of second-generation biofuel. Many industrial T. reesei strains currently in use are derived from strain Rut-C30, in which cellulase and hemicellulase expression is released from carbon catabolite repression. Nevertheless, inducing substances are still necessary for a satisfactory amount of protein formation.

Results

Here, we report on a T. reesei strain, which exhibits a very high level of xylanase expression regardless if inducing substances (e.g. D-xylose, xylobiose) are used. We found that a single point mutation in the gene encoding the Xylanase regulator 1 (Xyr1) is responsible for this strong deregulation of endo-xylanase expression and, moreover, a highly elevated basal level of cellulase expression. This point mutation is localized in a domain that is common in binuclear zinc cluster transcription factors. Only the use of sophorose as inducer still leads to a slight induction of cellulase expression. Under all tested conditions, the formation of cbh1 and cbh2 transcript level strictly follows the transcript levels of xyr1. The correlation of xyr1 transcript levels and cbh1/cbh2 transcript levels and also their inducibility via sophorose is not restricted to this strain, but occurs in all ancestor strains up to the wild-type QM6a.

Conclusions

Engineering a key transcription factor of a target regulon seems to be a promising strategy in order to increase enzymes yields independent of the used substrate or inducer. The regulatory domain where the described mutation is located is certainly an interesting research target for all organisms that also depend so far on certain inducing conditions.

【 授权许可】

   
2013 Derntl et al.; licensee BioMed Central Ltd.

【 图 表 】

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