title: Synergistic and Dose-Controlled Regulation of Cellulase Gene Expression in Penicillium oxalicum.
abstract: Filamentous fungus Penicillium oxalicum produces diverse lignocellulolytic enzymes, which are regulated by the combinations of many transcription factors. Here, a single-gene disruptant library for 470 transcription factors was constructed and systematically screened for cellulase production. Twenty transcription factors (including ClrB, CreA, XlnR, Ace1, AmyR, and 15 unknown proteins) were identified to play putative roles in the activation or repression of cellulase synthesis. Most of these regulators have not been characterized in any fungi before. We identified the ClrB, CreA, XlnR, and AmyR transcription factors as critical dose-dependent regulators of cellulase expression, the core regulons of which were identified by analyzing several transcriptomes and/or secretomes. Synergistic and additive modes of combinatorial control of each cellulase gene by these regulatory factors were achieved, and cellulase expression was fine-tuned in a proper and controlled manner. With one of these targets, the expression of the major intracellular β-glucosidase Bgl2 was found to be dependent on ClrB. The Bgl2-deficient background resulted in a substantial gene activation by ClrB and proved to be closely correlated with the relief of repression mediated by CreA and AmyR during cellulase induction. Our results also signify that probing the synergistic and dose-controlled regulation mechanisms of cellulolytic regulators and using it for reconstruction of expression regulation network (RERN) may be a promising strategy for cellulolytic fungi to develop enzyme hyper-producers. Based on our data, ClrB was identified as focal point for the synergistic activation regulation of cellulase expression by integrating cellulolytic regulators and their target genes, which refined our understanding of transcriptional-regulatory network as a "seesaw model" in which the coordinated regulation of cellulolytic genes is established by counteracting activators and repressors.
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Zhonghai
authors.initials: Z
authors.lastname: Li
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Guangshan
authors.initials: G
authors.lastname: Yao
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Ruimei
authors.initials: R
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Liwei
authors.initials: L
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Qinbiao
authors.initials: Q
authors.lastname: Kan
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Piao
authors.initials: P
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Guodong
authors.initials: G
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China; National Glycoengineering Research Center, Shandong University, Jinan, Shandong, China.
authors.forename: Yuqi
authors.initials: Y
authors.lastname: Qin
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Song
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Yaohua
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Fang
authors.affiliation: State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China; National Glycoengineering Research Center, Shandong University, Jinan, Shandong, China.
authors.forename: Yinbo
authors.initials: Y
authors.lastname: Qu
mesh_terms: D002480:Cellulase / Q000235:genetics* / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D053263:Gene Regulatory Networks; D005800:Genes, Fungal; D010407:Penicillium / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D059467:Transcriptome
chemical_list: D014157:Transcription Factors; D002482:Cellulose; D002480:Cellulase