Transcription Factor Sx1R Regulates Xylanase Genes in Trichoderma reesei

Trichoderma reesei is widely used cellulase production. However, its xylanase activity must be improved to enhance its ability to degrade lignocellulose. While several transcription factors play important roles in this process, Rui Liu from the Chinese Academy of Science want to focus on specific xylanase transcription factors that would regulate xylanase activity.

The team studied a novel zinc binuclear cluster transcription factor, designated as SxlR (specialized xylanase regulator). They found that it represses xylanase activity, but not cellulase activity. Further investigations revealed SxlR could bind to the promoters of xylanase genes (xyn1, xyn2, and xyn5) and directly regulate transcription and expression. Deletion of SxlR in T. reesei RUT-C30 generated the mutant ∆sxlr strain, which possesses higher xylanase activity as well as higher hydrolytic efficiency on pretreated rice straw.

This study revealed the transcriptional repressor of xylanase genes, Sx1R, which adds to the understanding of the regulatory system of cellulase and hemi-cellulase in T. reesei. The deletion of SxlR may also help improve the efficiency of T. reesei for lignocellulose degradation.