Redesigning transcription factor Cre1 for alleviating carbon catabolite repression in Trichoderma reesei

Abstract

Carbon catabolite repression (CCR), which is mainly mediated by Cre1 and triggered by glucose, leads to a decrease in cellulase production in Trichoderma reesei . Many studies have focused on modifying Cre1 for alleviating CCR. Based on the homologous alignment of CreA from wild-type Penicillium oxalicum 114–2 (Po-0) and cellulase hyperproducer JUA10-1(Po-1), we constructed a C-terminus substitution strain—Po-2—with decreased transcriptional levels of cellulase and enhanced CCR. Results revealed that the C-terminal domain of CreA Po−1 plays an important role in alleviating CCR. Furthermore, we replaced the C-terminus of Cre1 with that of CreA Po−1 in T. reesei (Tr-0) and generated Tr-1. As a control, the C-terminus of Cre1 was truncated and Tr-2 was generated. The transcriptional profiles of these transformants revealed that the C-terminal chimera greatly improves cellulase transcription in the presence of glucose and thus upregulates cellulase in the presence of glucose and weakens CCR, consistent with truncating the C-terminus of Cre1 in Tr-0. Therefore, we propose constructing a C-terminal chimera as a new strategy to improve cellulase production and alleviate CCR in the presence of glucose.

Transcriptional Activation of Biosynthetic Gene Clusters in Filamentous Fungi

“…Many STFs have been constructed to regulate genes in primary metabolism (Gao et al, 2017;Zhang et al, 2018;Han et al, 2020;Kun et al, 2021;Yamashita et al, 2021). Fusing the DNA-binding domain of the CreA/Cre1 (carbon catabolite repression) transcription factor to the complete Xyr1 transcription factor (Xylanase Regulator 1) resulted in enhanced cellulase production in a CreA/Cre1 deficient T. reesei strain grown on glucose (Zhang et al, 2017).…”

Tailoring in fungi for next generation cellulase production with special reference to CRISPR/CAS system

“…, and Xyr1 (xylanase regulator 1), primarily in T. reesei are the prime transcriptional activators of the genes encoding cellulase ( cbh1, cbh2, egl1 , and bgl1 ) enzymes [ 98 ] RXE1 It (RXE1 orthologs in Aspergillus chrysogenum, Beauveria bassiana , and Fusarium oxysporum are designated BRLA) regulate cellulase gene expression, exhibits intense binding activity to the xyr1 promoter [ 99 ] Rce1 It acts as a transcriptional repressor for cellulase gene expression by binding at the cbh1 promoter region, antagonized Xyr1 from binding to the cbh1 promoter [ 100 ] BglR It positively regulates the expression of genes encoding BGL in T. reesei . Its activation causes repression of the CBH and EG genes [ 101 ] ClbR In A. aculeatus it regulates cellulase-encoding genes induced by cellulose and cellobiose [ 102 ] Ace3 In T. reesei , its overexpression led to increase cellulase gene expression, while its removal causes a remarkable reduction in cellulase activity [ 103 ] CreA/Cre1 They regulates CCR (carbon catabolite repression) where, in the existence of simple sugars such as glucose, fructose, mannose or xylose, it suppresses the transcription of genes encoding enzymes involved in the metabolism of more complex polysaccharides [ 104 ] Crz1 Through the conduction of Ca 2+ /Mn 2+ mediated signalling, it affects the promoter region of xyr1 and cbh1, and induced cellulase production [ 105 ], [ 135 ] Ctf1 In T. reesei , it downregulate RCE1 gene, thus it upregulate genes of the transcription factors XYR1 and ACE3, resulting in the activation of cellulolytic genes [ 106 ] Clr-1/Clr-2/Clr-3 Activation of the Clr-1 r...…”

The chimeric GaaR-XlnR transcription factor induces pectinolytic activities in the presence of D-xylose in Aspergillus niger

“…The alteration of transcription factor specificity through the generation of chimeric transcription factors has been reported more than 30 years ago in yeasts (Corton 1989 ; Marmorstein and Harrison 1994 ; Witte and Dickson 1990 ). More recently, artificial transcription factors have been constructed in filamentous fungi to enhance the production of cellulases (Gao et al 2017 ; Han et al 2020 ; Zhang et al 2016 , 2017 , 2018a , 2018b ) or amylases (Yamashita et al 2021 ). However, the application of this technique to facilitate or enhance pectinase production has not yet been reported.…”