A fungal transcription factor essential for starch degradation affects integration of carbon and nitrogen metabolism

Abstract

In Neurospora crassa, the transcription factor COL-26 functions as a regulator of glucose signaling and metabolism. Its loss leads to resistance to carbon catabolite repression. Here, we report that COL-26 is necessary for the expression of amylolytic genes in N. crassa and is required for the utilization of maltose and starch. Additionally, the Δcol-26 mutant shows growth defects on preferred carbon sources, such as glucose, an effect that was alleviated if glutamine replaced ammonium as the primary nitrogen source. This rescue did not occur when maltose was used as a sole carbon source. Transcriptome and metabolic analyses of the Δcol-26 mutant relative to its wild type parental strain revealed that amino acid and nitrogen metabolism, the TCA cycle and GABA shunt were adversely affected. Phylogenetic analysis showed a single col-26 homolog in Sordariales, Ophilostomatales, and the Magnaporthales, but an expanded number of col-26 homologs in other filamentous fungal species. Deletion of the closest homolog of col-26 in Trichoderma reesei, bglR, resulted in a mutant with similar preferred carbon source growth deficiency, and which was alleviated if glutamine was the sole nitrogen source, suggesting conservation of COL-26 and BglR function. Our finding provides novel insight into the role of COL-26 for utilization of starch and in integrating carbon and nitrogen metabolism for balanced metabolic activities for optimal carbon and nitrogen distribution.

Broad substrate-specific phosphorylation events are associated with the initial stage of plant cell wall recognition inNeurospora crassa

“…COL-26/BglR (NCU07788) is a TF that has also been involved in glucose sensing/metabolism, regulation of starch degradation as well as the integration of carbon and nitrogen metabolism (Xiong et al, 2017; Xiong, Sun, et al, 2014). Six versions of two different phospho-peptides reveal four unique phosphorylation sites arranged in two pairs (S79/S83 and S674/S676).…”

Metabolic engineering of the cellulolytic thermophilic fungus Myceliophthora thermophila to produce ethanol from cellobiose

“…Of the 139 downregulated genes in M. thermophila cultured with cellobiose as the carbon source, those involved in ammonium transport, nitrogen metabolism, and membranes were the most enriched (Additional file 1: Table S5), suggesting a probable correlation between carbon and nitrogen metabolism in M. thermophila, as is the case in N. crassa [33].…”

“…CLR-2, CLR-3, XLR-1, CDT-2, and CLP1 are known to play essential roles in (hemi)-cellulose utilization by N. crassa [27][28][29][30][31]. Mycth_2301920, which was significantly induced by cellobiose as the carbon source, is the M. thermophila ortholog of the Zn(II)2Cys6 transcription factors AmyR in Aspergillus and COL-26 in N. crassa, which are essential for starch utilization [32][33][34].…”

Identification of a Novel Transcription Factor TP05746 Involved in Regulating the Production of Plant-Biomass-Degrading Enzymes in Talaromyces pinophilus

“…As a note of this complex regulatory network, TP05746 regulates not only the expression of genes encoding specific enzymes, but also that of other TF genes, such as AmyR, TpRfx1, and BglR. AmyR and BglR positively regulate fungal amylase production and negatively control cellulase and xylanase production (Nitta et al, 2012;Li et al, 2015;Xiong et al, 2017;Zhang et al, 2017), whereas TpRfx1 positively mediates PBDE production, including amylase, cellulase and xylanase, in T. pinopholus . However, the actual regulatory mechanism of TP05746 in fungal cells still needs to be further elucidated.…”

“…The Zn2Cys6 proteins AmyR and/or COL-26 are necessary for amylolytic gene expression in filamentous fungi such as P. oxalicum, N. crassa, T. pinophilus, Aspergillus spp., and are required for starch and maltose utilization Xiong et al, 2017;Zhang et al, 2017). Additionally, AmyR inhibits the expression of cellulase genes and its expression is regulated by ClrB in P. oxalicum .…”