CLR ‐4, a novel conserved transcription factor for cellulase gene expression in ascomycete fungi

Clr4, a novel conserved cellulase regulator inNeurosproa crassa andMyceliophthora thermophila was identified and functionally chararacterized. Clr4 activates cellulase gene expression through direct regulation of the major ligonocellulase regulators clr1/clr2/xyr ‐1 as well as via cr‐1, which is a key component of cAMP pathway. The findings reported here may prove helpful for industrial strain engineering for cellulase production and thus reduce the cost of biofuel production. SummaryFungal degradation of lignocellulosic biomass requires various (hemi ‐)cellulases and is an important part of the natural carbon cycle. Although induction of cellulases has been described for some saprobic filamentous fungi, the regulation of cellulase transcription is complex and many aspects are still poorly understood. Here, we identified and characterized the n ovel cellulase regulation factor NcCLR‐4 inNeurospora crassa and its ortholog MtCLR ‐4 inMyceliophthora thermophila. Deletion of CLR ‐4 resulted in similarly defective cellulolytic enzyme production and activities. Transcriptome analyses of ΔNcclr ‐4/ ΔMtclr ‐4 revealed the down ‐regulation of genes encoding (hemi‐)cellulases and pivotal regulators (clr ‐1,clr ‐2andxyr ‐1) and key genes in the cAMP signaling pathway such as adenylate cyclaseNccr ‐1. Intracellular cAMP levels were markedly lower in ΔNcclr ‐4/ ΔMtclr ‐4 than in wild ‐type during cellulose utilization. In electrophoretic mobility shif...

Source: Molecular Microbiology - November 25, 2018 Category: Microbiology Authors: Qian Liu, Jingen Li, Ranran Gao, Jinyang Li, Guoli Ma, Chaoguang Tian Tags: Research Article Source Type: research