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PubMed2026

Multi-omics analysis reveals Protein Kinase A-associated regulatory remodeling during adaptation of Trichoderma reesei to lignocellulosic substrate.

The filamentous fungus Trichoderma reesei is a major industrial source of holocellulolytic enzymes, and its response to complex carbon sources is regulated by nutrient-sensing mechanisms, including the cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling pathway. Here, we integrated transcriptomics, quantitative proteomics, and phosphoproteomics to analyze PKAc1-associated responses in the parental strain QM9414 and a Δpkac1 strain cultivated under glucose or sugarcane bagasse conditions. Deletion of pkac1 was associated with altered growth-related phenotypes and reduced extracellular activities of selected biomass-depolymerizing enzymes. Multi-omics profiling revealed condition-dependent changes affecting subsets of carbohydrate-active enzymes (CAZymes) genes and proteins, nutrient transporters, stress-associated proteins, and regulatory factors. Phosphoproteomics identified phosphorylation-state changes associated with pkac1 deletion, including reduced phosphorylation at sites enriched for the PKA consensus motif. In silico peptide docking was used to prioritize candidate PKAc1-associated substrates for future validation, including a Sec 7-derived peptide with favorable docking behavior relative to the control peptide. Together, these data support a working model in which PKAc1 contributes to regulatory and phosphorylation-state remodeling during adaptation to sugarcane bagasse, with effects on the magnitude and/or timing of selected CAZyme-related outputs in T. reesei.

Trichoderma↗
PubMed2026

Trichoderma reesei Nsd3 transcription factor: pleiotropic roles in development, stress response, secondary metabolism, and cellulase production.

Trichoderma reesei is known for its ability to secrete high amounts of cellulases, enzymes of fundamental importance in generating products from lignocellulosic biomass. Diverse signaling pathways and transcription factors (TFs) control the cellulolytic repertoire in T. reesei to ensure correct adaptation to the environment. Here, we analyzed RNA-Seq data and identified a new potential regulator of cellulase production in T. reesei: a novel TF named Nsd3, a homolog of NsdC from Aspergilli. Deletion of nsd3 reduced vegetative growth and conidiation on solid medium. Phenotypic characterization of the Δnsd3 strain showed that it is more sensitive to osmotic stress, but more resistant to cell wall and oxidative stresses. Our results showed that Nsd3 is a repressor of cellulase expression by directly regulating key genes in the cellulolytic pathway, an unreported role for this TF in fungi. Loss of nsd3 leads to a faster and more robust induction of cellulolytic genes, and higher cellulase and hemicellulase activities. Transcriptional profiling by RNA-Seq, chromatin accessibility profiling by ATAC-Seq, and protein-DNA interaction assays showed that sugar transporters are important targets of Nsd3 during cellulase expression regulation. Combined with microscopy and gene expression analyses, the ATAC-Seq data also highlighted Nsd3 as a central regulator of cell wall remodeling and organization. Furthermore, the transcriptomics also showed that Nsd3 regulates genes involved in secondary metabolism. These results showed that Nsd3 regulates several physiological processes and provide novel insights into the regulatory system of cellulases in T. reesei that can be used in the design of high-performance strains for biorefinery.IMPORTANCETrichoderma reesei is a key player in the production of hydrolytic enzymes for the degradation of lignocellulose biomass, and transcription factors are important targets for genetic engineering to construct cellulase-hyperproducing strains. Here, we identified the transcription factor Nsd3 and characterized its role as a regulator of cellulase production in T. reesei. We applied two powerful genomics methods (transcriptome sequencing and chromatin accessibility sequencing) to unravel the global role of Nsd3 and its regulatory mechanism. Nsd3 participates in various biological processes in T. reesei, including cell wall remodeling, calcium metabolism, and secondary metabolism, in addition to regulating the expression of sugar transporters. Protein-DNA interaction assays demonstrate that Nsd3 acts through important genes to regulate cellulase expression, including ace4, crt1, stp1, and cel1b. Our study provides mechanistic insights about how Nsd3 regulates diverse physiological processes in T. reesei. This work also applied ATAC-Seq for the first time to study chromatin accessibility in T. reesei.

ATAC-Seq↗
PubMed1978

alpha,alpha-Trehalase of Trichoderma reesei.

A simple adsorption and elution of the trehalase of Trichoderma reesei on bentonite increased the specific activity 70-80 times, with a recovery of 90%. This alpha,alpha-trehalase has an optimum pH of 4.4, a pl of 5.7, a Km of 3.1 X 10(-3) M, and a specific activity of 50 mumol/mg. min-1.

Adsorption↗
PubMed1979

Induction of cellulolytic enzymes in Trichoderma reesei by sophorose.

Sophorose (2-O-beta-glucopyranosyl-D-glucose) induces carboxymethyl cellulase in Trichoderma reesei QM6a mycelium with 1.5 to 2 h. The induction response to sophorose concentration, although complicated by the metabolism of sophorose, shows saturation kinetics. Most of the cellulase appears after most of the sophorose has been taken up, but the presence of an inducer is required to maintain cellulase synthesis because enzyme production ceases after separation of the mycelium from the induction medium. Cellulase appears simultaneously in the medium and in the mycelium, and no appreciable levels accumulate in the mycelium. Response to pH suggest either that synthesis and secretion of the enzyme are closely associated or concurrent events affected by surface interactions with the medium. Effects of temperature and pH on cellulase induction by sophorose are similar to those reported for induction by cellulose. The kinetics of absorption by mycelium differs from that of other beta-linked saccharides and glucose, the uptake of sophorose being much slower. Under our cultural conditions, sophorose appears to induce an incomplete array of cellulase enzymes, as indicated by enzymatic and electrophoretic studies.

Biological Transport↗
PubMed1977

Preparation of mutants of Trichoderma reesei with enhanced cellulase production.

The development of an agar plate screening technique has allowed the isolation of a range of mutants of Trichoderma reesei capable of synthesizing cellulase under conditions of high catabolite repression. The properties of one of these mutants (NG-14) is described to illustrate the use of this technique. NG-14 produced five times the filter paper-degrading activity per ml of culture medium and twice the specific activity per mg of excreted protein in submerged culture when compared with the best existing mutant, QM9414. NG-14 also showed enhanced endo-beta-glucanase and beta-glucosidase production. Although these mutants were isolated as cellulase producers in the presence of 5% glycerol on agar plates, in similar liquid medium, NG-14 exhibits only partial derepression of the cellulase complex. Since the proportions of filter paper activity, endo-beta-glucanase, and cellobiase were not the same in mutants NG-14 and QM9414, and the yields of each enzyme under conditions repressive for cellulase synthesis were different, differential control of each enzyme of the cellulase complex is implied. These initial results suggest that the selective technique for isolating hyper-cellulase-producing mutants of Trichoderma will be of considerable use in the development of commercially useful cellulolytic strains.

Cellulase↗
PubMed1979

Cellulase production and ammonia metabolism in Trichoderma reesei on high levels of cellulose.

Trichoderma can be cultured in stirred-tank fermentors on high (8%) cellulose concentrations without increasing the salt concentration of the medium when NH4OH is used to control pH and as a nitrogen source. Approximately 90% of the ammonia consumed by the organism can be added as NH4OH. The advantage of using high concentrations of cellulose is that culture filtrates with greater cellulase activity are obtained. The advantage of a low salts medium is that unwanted solutes in the final enzyme preparation are reduced. The appearance of cellulase in the medium occurs later than net ammonia uptake so that only 20% of the final amount of cellulase has appeared when 80% of the maximum amount of ammonia has been consumed.

Ammonia↗
PubMed1979

Production of cellulases by Trichoderma reesei QM 9414 in fed-batch and continuous-flow culture with cell recycle.

The scope in improving enzyme productivities from the cellulose fermentation process is examined in laboratory-scale fermentors. The maximum productivity (30 IU/liter hr) is attained in a continuous-culture process with cell recycle using modified medium containing 0.5% cellulose. Optimum dilution rate and recycle ratio are determined as 0.025 hr-1 and 1.2, respectively, for the process. The system is analyzed and steady-state equations for predicting enzyme protein concentrations in the fermentor are developed. In fed-batch cultures, slow addition of cellulose at high concentrations can improve enzyme productivity by as much as 33% over a batch process. The scope and results of using modified medium for cellulase production are also presented.

Cellulase↗
PubMed1979

Analysis of cellulase proteins by high-performance liquid chromatography.

A new procedure using high-performance liquid chromatography for the rapid separation of cellulase proteins is described. The cellulase components of Trichoderma reesei are fractionated on a DEAE anion-exchange column using a phosphate buffer at pH 6.2. Activities of the individual components obtained from T. reesei QM6a, a wild strain, and several mutant strains have been determined. Each system examined contained beta-glucosidase, at least two exo-beta-1,4 glucanases and five endo-beta-1,4 glucanases with the endo-beta-1,4 glucanases accounting for 20--36% and the exo-beta-1,4 glucanases for 64--80% of the soluble protein.

Cellulase↗
PubMed1979

[Cellobiose as a regulator of endoglucanase activity of cellulase complexes. Mechanism of the regulation].

Cellobiose may exert different effects on the activities of various endoglucanases. The endoglucanases of T. reesei and Rapidase are noticeably suppressed by cellobiose at concentrations above 3 mM. On the other hand, a low molecular weight endoglucanase from T. koningii is activated by cellobiose, whereas high molecular weight endoglucanases from the same source are inhibited by cellobiose. A detailed kinetic analysis of the effects showed that the low molecular weight endoglucanase is activated by a transglycosylation mechanism, in which cellobiose acts as an additional nucleophile. At saturating concentrations of cellobiose (Ks = 15 mM) the enzyme activity is increased 6-fold. Such a specific mechanism of activation manifests itself in an acceleration of random cleavage of CM-cellulose by the low molecular weight endoglucanase, which can be recorded by a viscosimetric technique. However, its action does not accelerate the production of soluble reducing sugars.

Cellobiose↗