A novel transcription factor specifically regulates GH11 xylanase genes in Trichoderma reesei

• Published in: Biotechnology for biofuels Vol. 10; no. 1; p. 194
• Main Authors: Liu, Rui, Chen, Ling, Jiang, Yanping, Zou, Gen, Zhou, Zhihua
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 03.08.2017; BioMed Central; BMC
• Subjects: Biodegradation; Bioinformatics; Biomass; Carbon; Cellulase; Cellulose; Clonal deletion; consensus sequence; Conserved sequence; CRISPR/Cas9; Electrophoretic mobility; endo-1,4-beta-glucanase; Enzymes; Fungi; gel electrophoresis; Gene expression; Genes; Genetic engineering; Glycoside hydrolase; Glycosides; Hemi-cellulase; industry; Lignocellulose; mutants; Polymerase chain reaction; Promoters; Proteins; quantitative polymerase chain reaction; repressor proteins; Rice straw; Secretion; Straw; transcription (genetics); Transcription factor; Transcription factors; Trichoderma reesei; Xylanase; xylanases; Zinc; CRISPR/Cas9; Xylanase; Transcription factor; Trichoderma reesei; Glycoside hydrolase; Hemi-cellulase
• ISSN: 1754-6834; 1754-6834; 2731-3654
• DOI: 10.1186/s13068-017-0878-x

The filamentous fungus is widely utilized in industry for cellulase production, but its xylanase activity must be improved to enhance the accessibility of lignocellulose to cellulases. Several transcription factors play important roles in this progress; however, nearly all the reported transcription factors typically target both cellulase and hemi-cellulase genes. Specific xylanase transcription factor would be useful to regulate xylanase activity directly. In this study, a novel zinc binuclear cluster transcription factor (jgi|Trire2|123881) was found to repress xylanase activity, but not cellulase activity, and was designated as SxlR (specialized xylanase regulator). Further investigations using real-time PCR and an electrophoretic mobility shift assay demonstrated that SxlR might bind the promoters of GH11 xylanase genes ( , , and ), but not those of GH10 ( ) and GH30 ( ) xylanase genes, and thus regulate their transcription and expression directly. We also identified the binding consensus sequence of SxlR as 5'- CATCSGSWCWMSA-3'. The deletion of SxlR in RUT-C30 to generate the mutant ∆ strain resulted in higher xylanase activity as well as higher hydrolytic efficiency on pretreated rice straw. Our study characterizes a novel specific transcriptional repressor of GH11 xylanase genes, which adds to our understanding of the regulatory system for the synthesis and secretion of cellulase and hemi-cellulase in . The deletion of SxlR may also help to improve the hydrolytic efficiency of for lignocellulose degradation by increasing the xylanase-to-cellulase ratio.