scholarly journals Global Reprogramming of Gene Transcription in Trichoderma reesei by Overexpressing an Artificial Transcription Factor for Improved Cellulase Production and Identification of Ypr1 as an Associated Regulator

Author(s):  
Fei Zhang ◽  
Jia-Xiang Li ◽  
Verawat Champreda ◽  
Chen-Guang Liu ◽  
Feng-Wu Bai ◽  
...  
2021 ◽  
Vol 7 (8) ◽  
pp. 613
Author(s):  
Xiuzhen Chen ◽  
Bingran Song ◽  
Minglu Liu ◽  
Lina Qin ◽  
Zhiyang Dong

Vib1, a member of the Ndt80/PhoG-like transcription factor family, has been shown to be essential for cellulase production of Trichoderma reesei. Here, we combined transcriptomic and genetic analyses to gain mechanistic insights into the roles of Vib1 during cellulose degradation. Our transcriptome analysis showed that the vib1 deletion caused 586 genes with decreased expression and 431 genes with increased expression on cellulose. The downregulated genes were enriched for Gene Ontology terms associated with carbohydrate metabolism, transmembrane transport, oxidoreductase activity, and transcription factor activity. Of the 258 genes induced by cellulose, 229 showed no or decreased expression in Δvib1 on cellulose, including almost all (hemi)cellulase genes, crucial sugar transporter genes (IDs:69957, 3405), and the genes encoding main transcriptional activators Xyr1 and Ace3. Additionally, Vib1 also regulated the expression of genes involved in secondary metabolism. Further comparison of the transcriptomes of Δvib1 and Δxyr1 in cellulose revealed that the genes regulated by Vib1 had much overlap with Xyr1 targets especially for the gene set induced by cellulose, presumably whose expression requires the cooperativity between Vib1 and Xyr1. Genetic evidence indicated that Vib1 regulates cellulase gene expression partially via Xyr1. Our results will provide new clues for strain improvement.


Author(s):  
Yumeng Chen ◽  
Aibo Lin ◽  
Pei Liu ◽  
Xingjia Fan ◽  
Chuan Wu ◽  
...  

The filamentous fungus Trichoderma reesei is a model strain for cellulase production. Cellulase gene expression in T. reesei is controlled by multiple transcription factors. Here, we identified by comparative genomic screening a novel transcriptional activator ACE4 ( A ctivator of c ellulase e xpression 4) that positively regulates cellulase gene expression on cellulose in T. reesei . Disruption of the ace4 gene significantly decreased expression of four main cellulase genes, and the essential cellulase transcription factor encoding gene ace3 . Overexpression of ace4 increased cellulase production by approximately 22% compared to that in the parental strain. Further investigations using electrophoretic mobility shift assays, DNase I footprinting assays, and chromatin immunoprecipitation assays indicated that ACE4 directly binds to the promoter of cellulase genes by recognizing the two adjacent 5′-GGCC-3′ sequences. Additionally, ACE4 directly binds to the promoter of ace3 and, in turn, regulates the expression of ACE3 to facilitate cellulase production. Collectively, these results demonstrate an important role for ACE4 in regulating cellulase gene expression, which will contribute to understanding the mechanism underlying cellulase expression in T. reesei . IMPORTANCE T. reesei is commonly utilized in industry to produce cellulases, enzymes that degrade lignocellulosic biomass for the production of bioethanol and bio-based products. T. reesei is capable of rapidly initiating the biosynthesis of cellulases in the presence of cellulose, which has made it useful as a model fungus for studying gene expression in eukaryotes. Cellulase gene expression is controlled through multiple transcription factors at the transcriptional level. However, the molecular mechanisms by which transcription is controlled remain unclear. In the present study, we identified a novel transcription factor, ACE4, which regulates cellulase expression on cellulose by binding to the promoters of cellulase genes and the cellulase activator ace3 . Our study not only expands the general functional understanding of the novel transcription factor ACE4 but also provides evidence for the regulatory mechanism mediating gene expression in T. reesei .


2020 ◽  
Author(s):  
Lijuan Han ◽  
Yinshuang Tan ◽  
Wei Ma ◽  
Kangle Niu ◽  
Shaoli Hou ◽  
...  

SummaryIn Trichoderma reesei, carbon catabolite repression (CCR) significantly downregulates the transcription of cellulolytic enzymes, which is usually mediated by the zinc finger protein Cre1. It was found that there is a conserved region at the C-terminus of Cre1/CreA in several cellulase-producing fungi that contains up to three continuous S/T phosphorylation sites. Here, S387, S388, T389, and T390 at the C-terminus of Cre1 in T. reesei were mutated to valine for mimicking an unphosphorylated state, thereby generating the transformants Tr_Cre1S387V, Tr_Cre1S388V, Tr_Cre1T389V, and Tr_Cre1T390V, respectively. Transcription of cel7a in Tr_ Cre1S388V was markedly higher than that of the parent strain when grown in glucose-containing media. Under these conditions, both filter paperase (FPase) and p-nitrophenyl-β-D-cellobioside (pNPCase) activities, as well as soluble proteins from Tr_Cre1S388V were significantly increased by up to 2- to 3-fold compared with that of other transformants and the parent strain. To our knowledge, this is the first report demonstrating an improvement of cellulase production in fungal species under CCR by mimicking dephosphorylation at the C-terminus of Cre1. Taken together, we developed a precision engineering strategy based on the modification of phosphorylation sites of Cre1 transcription factor to enhance the production of cellulase in fungal species under CCR.


2018 ◽  
Vol 63 (2) ◽  
pp. 115-129
Author(s):  
Rahela Carpa ◽  
◽  
Alin Cândea ◽  
Alexei Remizovschi ◽  
Lucian Barbu-Tudoran ◽  
...  

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Yumeng Chen ◽  
Xingjia Fan ◽  
Xinqing Zhao ◽  
Yaling Shen ◽  
Xiangyang Xu ◽  
...  

Abstract Background The filamentous fungus Trichoderma reesei is one of the best producers of cellulase and has been widely studied for the production of cellulosic ethanol and bio-based products. We previously reported that Mn2+ and N,N-dimethylformamide (DMF) can stimulate cellulase overexpression via Ca2+ bursts and calcium signalling in T. reesei under cellulase-inducing conditions. To further understand the regulatory networks involved in cellulase overexpression in T. reesei, we characterised the Mn2+/DMF-induced calcium signalling pathway involved in the stimulation of cellulase overexpression. Results We found that Mn2+/DMF stimulation significantly increased the intracellular levels of cAMP in an adenylate cyclase (ACY1)-dependent manner. Deletion of acy1 confirmed that cAMP is crucial for the Mn2+/DMF-stimulated cellulase overexpression in T. reesei. We further revealed that cAMP elevation induces a cytosolic Ca2+ burst, thereby initiating the Ca2+ signal transduction pathway in T. reesei, and that cAMP signalling causes the Ca2+ signalling pathway to regulate cellulase production in T. reesei. Furthermore, using a phospholipase C encoding gene plc-e deletion strain, we showed that the plc-e gene is vital for cellulase overexpression in response to stimulation by both Mn2+ and DMF, and that cAMP induces a Ca2+ burst through PLC-E. Conclusions The findings of this study reveal the presence of a signal transduction pathway in which Mn2+/DMF stimulation produces cAMP. Increase in the levels of cAMP activates the calcium signalling pathway via phospholipase C to regulate cellulase overexpression under cellulase-inducing conditions. These findings provide insights into the molecular mechanism of the cAMP–PLC–calcium signalling pathway underlying cellulase expression in T. reesei and highlight the potential applications of signal transduction in the regulation of gene expression in fungi.


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