期刊
BIOTECHNOLOGY FOR BIOFUELS
卷 8, 期 -, 页码 -出版社
BIOMED CENTRAL LTD
DOI: 10.1186/s13068-015-0298-8
关键词
Trichoderma reesei; Xylanases; Cellulases; Gene regulation; Transcription factor; Cellulosic ethanol
资金
- Austrian Science Fund (FWF) [P24851, V232]
- doctoral program (AB-Tec) of Vienna University of Technology
- Austrian Science Fund (FWF) [P 24851, V 232] Funding Source: researchfish
- Austrian Science Fund (FWF) [P24851, V232] Funding Source: Austrian Science Fund (FWF)
Background: The ascomycete Trichoderma reesei is industrially used for the production of cellulases. During the production process xylanases are co-secreted, which uses energy and nutrients. Cellulases and xylanases share the same main regulators, which makes a knowledge-based strain design difficult. However, previously a cis-element in the promoter of the main xylanase-encoding gene was identified as binding site for a putative repressor. Subsequently, three candidate repressors were identified in a pull-down approach. The expression of the most promising candidate, Xpp1 (Xylanase promoter-binding protein 1), was reported to be up-regulated on the repressing carbon source D-glucose and to bind the cis-element in vitro. Results: In this study, Xpp1 was deleted and over-expressed in T. reesei. An in vivo DNA-footprint assay indicated that Xpp1 binds a palindromic sequence in the xyn2 promoter. Comparison of the deletion, the over-expression, and the parent strain demonstrated that Xpp1 regulates gene expression of xylanolytic enzymes at later cultivation stages. Xpp1 expression was found to be up-regulated, additionally to D-glucose, by high D-xylose availability. These findings together with the observed xyn2 transcript levels during growth on xylan suggest that Xpp1 is the mediator of a feedback mechanism. Notably, Xpp1 has neither influence on the d-xylose metabolism nor on the expression of cellulases. Conclusions: Xpp1 as regulator acting on the expression of xylanases, but not cellulases, is a highly promising candidate for knowledge-based strain design to improve the cellulases-to-xylanases ratio during industrial cellulase production.
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