ABSTRACT: Identification of direct target genes of the Neurospora crassa essential plant biomass deconstruction transcription factors CLR-1, CLR-2 and XLR-1
Project description:abstract: The plant cell wall is composed of many complex polymers, and its deconstruction requires an equally complex orchestration of a wide array of enzymes. In Neurospora crassa, clr-1, clr-2 and xlr-1 have been identified as the key transcription factors involved in cell wall breakdown. In order to define their regulons, we performed ChIPseq upon these three transcription factors. CLR-1, CLR-2 and XLR-1 each bind to the most highly and differentially expressed gene populations, which include the cellulases for the CLRs and the hemicellulases for XLR-1. CLR-1 also bound to its regulon under non-inducing conditions; however, this did not translate into gene expression. Motif analysis of the bound genes revealed conserved DNA binding motifs, with the CLR-2 motif matching that of its closest yeast homolog, GAL4. Co-immunoprecipitation studies were able to show that CLR-1 and CLR-2 act as homodimers. Finally, we report on a conserved XLR-1 point mutation that is sufficient to drive hemicellulase expression under non-inducing conditions. Understanding how these transcription factors work in concert to break down plant biomass can inform decisions on how to best engineer future fungal strains for decreased enzyme costs. RNAseq and ChIPseq was performed upon knockout mutants and wild type strains growing on various carbon sources to determin the role of the transcription factors CLR-1, CLR-2, and XLR-1 in plant cell wall degradation
Project description:abstract: The plant cell wall is composed of many complex polymers, and its deconstruction requires an equally complex orchestration of a wide array of enzymes. In Neurospora crassa, clr-1, clr-2 and xlr-1 have been identified as the key transcription factors involved in cell wall breakdown. In order to define their regulons, we performed ChIPseq upon these three transcription factors. CLR-1, CLR-2 and XLR-1 each bind to the most highly and differentially expressed gene populations, which include the cellulases for the CLRs and the hemicellulases for XLR-1. CLR-1 also bound to its regulon under non-inducing conditions; however, this did not translate into gene expression. Motif analysis of the bound genes revealed conserved DNA binding motifs, with the CLR-2 motif matching that of its closest yeast homolog, GAL4. Co-immunoprecipitation studies were able to show that CLR-1 and CLR-2 act as homodimers. Finally, we report on a conserved XLR-1 point mutation that is sufficient to drive hemicellulase expression under non-inducing conditions. Understanding how these transcription factors work in concert to break down plant biomass can inform decisions on how to best engineer future fungal strains for decreased enzyme costs. RNAseq and ChIPseq upon knockout mutants and sild type growing on various carbon sources to determin the role of the transcription factors: CLR-1, CLR-2, and XLR-1 in plant cell wall degradation
Project description:Fungal degradation of lignocellulosic biomass requires various (hemi-)cellulases and plays key roles in biological carbon cycle. Although cellulases induction recently described in some saprobic filamentous fungi, regulation of cellulase transcription has not been studied thoroughly. Here, we identified and characterized the novel cellulase regulation factors clr-4 in Neurospora crassa and its ortholog Mtclr-4 in Myceliophthora thermophila. Deletion of clr-4 and Mtclr-4 displayed similarly defective phenotypes in cellulolytic enzymes production and activities. Transcriptomics analysis of Δclr-4/ΔMtclr-4 revealed down-regulation of not only encoding genes of (hemi-)cellulases and pivotal regulators (clr-1, clr-2 and xyr-1), but also the key genes of cAMP signaling pathway such as adenylate cyclase cr-1. Consistently, the significant decreased levels of intracellular cAMP were observed in Δclr-4/ΔMtclr-4 compared to wild-type during cellulose utilization. Electrophoretic mobility shift assays (EMSA) verified that CLR-4 could directly bind to the promoter regions of adenylyl cyclase (Nccr-1) and cellulose regulator clr-1, while MtCLR-4 bind to upstream regions of adenylyl cyclase Mtcr-1 and biomass deconstruction regulators Mtclr-2 and Mtxyr-1. Concluded, the novel cellulase expression regulators (CLR-4/MtCLR-4) findings here significantly enrich our understanding of the regulatory network of cellulose degradation and provide new targets for industrial fungi strain engineering for plant biomass deconstruction in biorefinery.
Project description:Identification of direct target genes of the Neurospora crassa essential plant biomass deconstruction transcription factors CLR-1, CLR-2 and XLR-1 (ChIP-Seq)
Project description:Identification of direct target genes of the Neurospora crassa essential plant biomass deconstruction transcription factors CLR-1, CLR-2 and XLR-1 (RNA-Seq)
Project description:Cellulose, particularly the major cellulolytic product cellobiose, can induce the production of enzymes associated with deconstruction of lignocellulose in filamentous fungi. However, the detailed mechanisms underlying this biotechnologically important process remain to be disclosed. Here, the proteome response to cellobiose, crystalline cellulose (Avicel), and carbon starvation of a Neurospora crassa triple β-glucosidase mutant were compared using tandem mass tag (TMT)-based proteome quantification. Improved quantification accuracy was achieved with synchronous precursor selection (SPS)-based MS3 technology compared to MS2 using a high resolution tribrid mass spectrometer. Exposure to carbon starvation, cellobiose or Avicel induced the production of cellulase and lytic polysaccharide monooxygenase enzymes in N. crassa, as well as a cellobionic acid transporter, indicating their functional roles in the early adaptation to plant cell wall. In particular, cellobiose specifically induced the production of proteins in the functional categories of protein processing and export as well as cell wall organization. The data presented here integrates the signaling pathway associated with cellobiose transporters CDT-1 and/or CDT-2 with the direct targets of the transcription factors CLR-1, CLR-2, and XLR-1, the unfolded protein response (UPR) mediated by Ire-1/Hac-1, as well as calcium homeostasis and cell wall organization. The cellobiose-dependent response network will be useful for rational strain improvement to facilitate the production of lignocellulases in filamentous fungi and plant biomass-based products.
Project description:abstract: The plant cell wall is composed of many complex polymers, and its deconstruction requires an equally complex orchestration of a wide array of enzymes. In Neurospora crassa, clr-1, clr-2 and xlr-1 have been identified as the key transcription factors involved in cell wall breakdown. In order to define their regulons, we performed ChIPseq upon these three transcription factors. CLR-1, CLR-2 and XLR-1 each bind to the most highly and differentially expressed gene populations, which include the cellulases for the CLRs and the hemicellulases for XLR-1. CLR-1 also bound to its regulon under non-inducing conditions; however, this did not translate into gene expression. Motif analysis of the bound genes revealed conserved DNA binding motifs, with the CLR-2 motif matching that of its closest yeast homolog, GAL4. Co-immunoprecipitation studies were able to show that CLR-1 and CLR-2 act as homodimers. Finally, we report on a conserved XLR-1 point mutation that is sufficient to drive hemicellulase expression under non-inducing conditions. Understanding how these transcription factors work in concert to break down plant biomass can inform decisions on how to best engineer future fungal strains for decreased enzyme costs.
Project description:abstract: The plant cell wall is composed of many complex polymers, and its deconstruction requires an equally complex orchestration of a wide array of enzymes. In Neurospora crassa, clr-1, clr-2 and xlr-1 have been identified as the key transcription factors involved in cell wall breakdown. In order to define their regulons, we performed ChIPseq upon these three transcription factors. CLR-1, CLR-2 and XLR-1 each bind to the most highly and differentially expressed gene populations, which include the cellulases for the CLRs and the hemicellulases for XLR-1. CLR-1 also bound to its regulon under non-inducing conditions; however, this did not translate into gene expression. Motif analysis of the bound genes revealed conserved DNA binding motifs, with the CLR-2 motif matching that of its closest yeast homolog, GAL4. Co-immunoprecipitation studies were able to show that CLR-1 and CLR-2 act as homodimers. Finally, we report on a conserved XLR-1 point mutation that is sufficient to drive hemicellulase expression under non-inducing conditions. Understanding how these transcription factors work in concert to break down plant biomass can inform decisions on how to best engineer future fungal strains for decreased enzyme costs.
Project description:Comparative transcriptional profiling of N. crassa grown on five major crop straws of China (barley, corn, rice, soybean and wheat straws) revealed a highly overlapping group of 430 genes, the Biomass commonly Induced Core Set (BICS). A large proportion of induced carbohydrate-active-enzyme (CAZy) genes (82 out of 113) were also conserved across the five plant straws. Excluding 178 genes within the BICS that were also up-regulated under no-carbon conditions, the remaining 252 genes were defined as the Biomass Regulon (BR). Interestingly, 88 genes were only induced by plant biomass and not by three individual polysaccharides (Avicel, xylan, and pectin); these were denoted as the Biomass Unique Set (BUS). Deletion of one BUS gene, the transcriptional regulator rca-1, significantly improved lignocellulase production using plant biomass as the sole carbon source, possibly functioning via de-repression of the regulator clr-2. Thus, this result suggests that rca-1 is a potential engineering target for biorefineries, especially for plant biomass direct microbial conversion processes. Conidia of Neurospora crass wild type were inoculated at 10^6 conidia/mL into 100 mL 1×Vogel’s salts with 2% (w/w) ground crop straws, barley straw, corn straw, rice straw, soybean straw and wheat straw respectively for 30 h or 2% sucrose for 16 h. Then, mycelia were harvested through filtration and immediately frozen in liquid nitrogen.Total RNA from frozen sample was isolated with TRIzol reagent (Invitrogen) and further treated with DNase I (RNeasy Mini Kit, QIAGEN). The qualified RNA was prepared with standard protocol from Shenzhen BGI (China) and sequenced on the Illumina HiSeqTM 2000 platform.
Project description:Comparative transcriptional profiling of N. crassa grown on five major crop straws of China (barley, corn, rice, soybean and wheat straws) revealed a highly overlapping group of 430 genes, the Biomass commonly Induced Core Set (BICS). A large proportion of induced carbohydrate-active-enzyme (CAZy) genes (82 out of 113) were also conserved across the five plant straws. Excluding 178 genes within the BICS that were also up-regulated under no-carbon conditions, the remaining 252 genes were defined as the Biomass Regulon (BR). Interestingly, 88 genes were only induced by plant biomass and not by three individual polysaccharides (Avicel, xylan, and pectin); these were denoted as the Biomass Unique Set (BUS). Deletion of one BUS gene, the transcriptional regulator rca-1, significantly improved lignocellulase production using plant biomass as the sole carbon source, possibly functioning via de-repression of the regulator clr-2. Thus, this result suggests that rca-1 is a potential engineering target for biorefineries, especially for plant biomass direct microbial conversion processes.