ACEII, a Novel Transcriptional Activator Involved in Regulation of Cellulase and Xylanase Genes of Trichoderma reesei

Abstract

A novel yeast-based method to isolate transcriptional activators was applied to clone regulators binding to the cellulase promoter cbh1 of the filamentous fungus Trichoderma reesei (Hypocrea jecorina). This led to the isolation of the cellulase activator ace2 encoding for a protein belonging to the class of zinc binuclear cluster proteins found exclusively in fungi. The DNA-binding domain of ACEII was expressed as a glutathione S-transferase fusion protein in Escherichia coli, and ACEII was shown to bind in vitro to the 5-GGCTAATAA site present in the cbh1 promoter. This site also contains the proposed binding sequence of the xylanase activator XlnR of Aspergillus niger. Mutation of the GGC triplet abolished ACEII binding. The function of ACEII was studied by analyzing the effects of ace2 deletion in the hypercellulolytic T. reesei strain ALKO2221. Deletion of the ace2 gene led to lowered induction kinetics of mRNAs encoding the major cellulases cellobiohydrolases I and II and endoglucanases I and II and to 30 -70% reduced cellulase activity when the fungus was grown on medium containing Solka floc cellulose. The expression level of the gene encoding xylanase was also affected. ace2 deletion led to lowered xyn2 expression in cellulose-induced cultivation. Cellulase induction by sophorose was not affected by ace2 deletion.

Microbial Cellulose Utilization: Fundamentals and Biotechnology

“…Expression of the cellulase genes (cbh1, cbh2, egl1, egl2, and egl5) of T. reesei QM9414 is coordinated through transcription factors (296). The genes encoding the transcriptional factors ACEI (585) and ACEII (18) were identified based on their ability to bind to the T. reesei cbh1 promoter region and subsequently their DNA sequences were determined. ACEII is homologous to XlnR (700), a transcriptional activator identified in Aspergillus niger, and ACEII also stimulates the expression of cellulase and xylanase genes.…”

Regulation of transcription of cellulases- and hemicellulases-encoding genes in Aspergillus niger and Hypocrea jecorina (Trichoderma reesei)

“…Further studies (Würleitner et al 2003) using in vitro as well as in vivo strategies, identified nucleotide sequences within 55 bp being essential for the binding of proteins and being responsible for the xyn2 regulation. It could be demonstrated that a protein-DNA complex related to both, basal transcription as well as induction of the xyn2 expression, consists of at least the Hap2/3/5 complex (Zeilinger et al 2001) and of Ace2 (Aro et al 2001), contacting an undecameric motif 5′-GGGTAAATTGG-3′ (XAE; xylanase-activating element). The Hap2/3/5 complex contacts the CCAAT box within this motif.…”

Solid-State Fermentation of Ammoniated Corn Straw to Animal Feed by Pleurotus ostreatus Pl-5

“…In addition, more available cellulose and N content in the EP may have been the main reasons for the stimulation of cellulase production. More available cellulose was an environmental stress that induced the cellulase production (Aro et al 2001;Montoya et al 2012), and the high N content made it easier for fungal growth and cellulase synthesis.…”