Trichoderma reesei CRE1-mediated Carbon Catabolite Repression in Response to Sophorose Through RNA Sequencing Analysis

Abstract

Carbon catabolite repression (CCR) mediated by CRE1 in Trichoderma reesei emerged as a mechanism by which the fungus could adapt to new environments. In the presence of readily available carbon sources such as glucose, the fungus activates this mechanism and inhibits the production of cellulolytic complex enzymes to avoid unnecessary energy expenditure. CCR has been well described for the growth of T. reesei in cellulose and glucose, however, little is known about this process when the carbon source is sophorose, one of the most potent inducers of cellulase production. Thus, we performed high-throughput RNA sequencing to better understand CCR during cellulase formation in the presence of sophorose, by comparing the mutant ∆cre1 with its parental strain, QM9414. Of the 9129 genes present in the genome of T. reesei, 184 were upregulated and 344 downregulated in the mutant strain ∆cre1 compared to QM9414. Genes belonging to the CAZy database, and those encoding transcription factors and transporters are among the gene classes that were repressed by CRE1 in the presence of sophorose; most were possible indirectly regulated by CRE1. We also observed that CRE1 activity is carbon-dependent. A recent study from our group showed that in cellulose, CRE1 repress different groups of genes when compared to sophorose. CCR differences between these carbon sources may be due to the release of cellodextrins in the cellulose polymer, resulting in different targets of CRE1 in both carbon sources. These results contribute to a better understanding of CRE1-mediated CCR in T. reesei when glucose comes from a potent inducer of cellulase production such as sophorose, which could prove useful in improving cellulase production by the biotechnology sector.

Understanding the Role of the Master Regulator XYR1 in Trichoderma reesei by Global Transcriptional Analysis

“…In addition, Antoniêto et al ( 2014 ) showed that in the Δ cre1 mutant strain the expression of amino acid transporters was induced in the presence of cellulose. In addition, during growth in sophorose, expression of the amino acid transporter in the Δ cre1 mutant strain was also induced, indicating that CRE1 acts to inhibit these genes (Antoniêto et al, 2016 ). Similarly, our results pointed to the downregulation of amino acid transporters in sophorose-grown cultures in the Δ xyr1 mutant strain, as well as in cellulose.…”

CRZ1 regulator and calcium cooperatively modulate holocellulases gene expression in Trichoderma reesei QM6a

“…The complex network that coordinates holocellulases expression in T. reesei is also under regulation of nutritional variability. Therefore, differential gene expression was discussed by Castro et al (2014b) and Antoniêto et al (2016) in studies that reported the influence of carbon source on holocellulases transcription. Robust techniques like RNA sequencing have already highlighted the importance of sugar availability on the regulation mediated by TFs in T. reesei (Castro et al, 2016), evidencing the growing need of elucidating deep layers of regulation in this fungus.…”

Co-culture of Vel1-overexpressed Trichoderma asperellum and Bacillus amyloliquefaciens: An eco-friendly strategy to hydrolyze the lignocellulose biomass in soil to enrich the soil fertility, plant growth and disease resistance

“…Knockout of ACE1 and RCE1 improved the synthesis of cellulase and xylanase [26,27]. The carbon catabolic repression has been regulated by the negative regulation of CRE1 gene [28]. Transcript data of ACEI, RCE1, and CRE1 of the present study were downregulated in the TA OE-Vel1 strain (Fig.…”