A Novel Cys2His2 Zinc Finger Homolog of AZF1 Modulates Holocellulase Expression in italic toggle="yes">Trichoderma reesei /italic

• Published in: mSystems Vol. 4; no. 4
• Main Authors: Amanda Cristina Campos Antonieto, Karoline Maria Vieira Nogueira, Renato Graciano de Paula, Luísa Czamanski Nora, Murilo Henrique Anzolini Cassiano, Maria-Eugenia Guazzaroni, Fausto Almeida, Thiago Aparecido da Silva, Laure Nicolas Annick Ries, Leandro Jose de Assis, Gustavo Henrique Goldman, Roberto Nascimento Silva, Rafael Silva-Rocha
• Format: Journal Article
• Language: English
• Published: American Society for Microbiology 01.08.2019
• Subjects: cis-regulatory elements; holocellulase expression; regulatory networks; systems biology
• DOI: 10.1128/mSystems.00161-19

ABSTRACT Filamentous fungi are remarkable producers of enzymes dedicated to the degradation of sugar polymers found in the plant cell wall. Here, we integrated transcriptomic data to identify novel transcription factors (TFs) related to the control of gene expression of lignocellulosic hydrolases in Trichoderma reesei and Aspergillus nidulans. Using various sets of differentially expressed genes, we identified some putative cis-regulatory elements that were related to known binding sites for Saccharomyces cerevisiae TFs. Comparative genomics allowed the identification of six transcriptional factors in filamentous fungi that have corresponding S. cerevisiae homologs. Additionally, a knockout strain of T. reesei lacking one of these TFs (S. cerevisiae AZF1 homolog) displayed strong reductions in the levels of expression of several cellulase-encoding genes in response to both Avicel and sugarcane bagasse, revealing a new player in the complex regulatory network operating in filamentous fungi during plant biomass degradation. Finally, RNA sequencing (RNA-seq) analysis showed the scope of the AZF1 homologue in regulating a number of processes in T. reesei, and chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) provided evidence for the direct interaction of this TF in the promoter regions of cel7a, cel45a, and swo. Therefore, we identified here a novel TF which plays a positive effect in the expression of cellulase-encoding genes in T. reesei. IMPORTANCE In this work, we used a systems biology approach to map new regulatory interactions in Trichoderma reesei controlling the expression of genes encoding cellulase and hemicellulase. By integrating transcriptomics related to complex biomass degradation, we were able to identify a novel transcriptional regulator which is able to activate the expression of these genes in response to two different cellulose sources. In vivo experimental validation confirmed the role of this new regulator in several other processes related to carbon source utilization and nutrient transport. Therefore, this work revealed novel forms of regulatory interaction in this model system for plant biomass deconstruction and also represented a new approach that could be easy applied to other organisms.