Interdependent recruitment of CYC8/TUP1 and the transcriptional activator XYR1 at target promoters is required for induced cellulase gene expression in < i > Trichoderma reesei < /i >

by Lei Wang, Weixin Zhang, Yanli Cao, Fanglin Zheng, Guolei Zhao, Xinxing Lv, Xiangfeng Meng, Weifeng Liu

Cellulase production in filamentous fungusTrichoderma reesei is highly responsive to various environmental cues involving multiple positive and negative regulators. XYR1 (Xylanase regulator 1) has been identified as the key transcriptional activator of cellulase gene expression inT.reesei. However, the precise mechanism by which XYR1 achieves transcriptional activation of cellulase genes is still not fully understood. Here, we identified the TrCYC8/TUP1 complex as a novel coactivator for XYR1 inT.reesei. CYC8/TUP1 is the first identified transcriptional corepressor complex mediating repression of diverse genes inSaccharomyces cerevisiae. Knockdown ofTrcyc8 orTrtup1 resulted in markedly impaired cellulase gene expression inT.reesei. We found that TrCYC8/TUP1 was recruited to cellulase gene promoters upon cellulose induction and this recruitment is dependent on XYR1. We further observed that repressedTrtup1 orTrcyc8 expression caused a strong defect in XYR1 occupancy and loss of histone H4 at cellulase gene promoters. The defects in XYR1 binding and transcriptional activation of target genes inTrtup1 orTrcyc8 repressed cells could not be overcome by XYR1 overexpression. Our results reveal a novel coactivator function for TrCYC8/TUP1 at the level of activator binding, and suggest a mechanism in which interdependent recruitment of XYR1 and TrCYC8/TUP1 to cellulase gene promo...

Source: PLoS Genetics - February 19, 2021 Category: Genetics & Stem Cells Authors: Lei Wang Source Type: research