Sucrose-nonfermenting 1 kinase activates histone acetylase GCN5 to promote cellulase production in Trichoderma.

Trichoderma serves as the primary producer of cellulases and hemicellulases in industrial settings as it readily secretes a variety of cellulolytic enzymes. The protein kinase SNF1 (sucrose-nonfermenting 1) can enable cells to adapt to changes in carbon metabolism by phosphorylating key rate-limiting enzymes involved in the maintenance of energy homeostasis and carbon metabolism within cells. Histone acetylation is an important epigenetic regulatory mechanism that influences physiological and biochemical processes. GCN5 is a representative histone acetylase involved in promoter chromatin remodeling and associated transcriptional activation. Here, the TvSNF1 and TvGCN5 genes were identified in Trichoderma viride Tv-1511, which exhibits promising activity with respect to its ability to produce cellulolytic enzymes for biological transformation. The SNF1-mediated activation of the histone acetyltransferase GCN5 was herein found to promote cellulase production in T. viride Tv-1511 via facilitating changes in histone acetylation. These results demonstrated that cellulolytic enzyme activity and the expression of genes encoding cellulases and transcriptional activators were clearly enhanced in T. viride Tv-1511 mutants in which TvSNF1 and TvGCN5 were overexpressed, with concomitant changes in histone H3 acetylation levels associated with these genes. GCN5 was also found to be directly recruited to promoter regions to alter histone acetylation, while SNF1 functioned upstream as a transcriptional activator that promotes GCN5 upregulation at the mRNA and protein levels in the context of cellulase induction in T. viride Tv-1511. These findings underscore the important role that this SNF1-GCN5 cascade plays in regulating cellulase production in T. viride Tv-1511 by promoting altered histone acetylation, offering a theoretical basis for the optimization of T. viride in the context of industrial cellulolytic enzyme production. KEY POINTS: • SNF1 kinase and GCN5 acetylase promoted cellulase production in Trichoderma by increasing the expression of genes encoding cellulases and transcriptional activators • SNF1 and GCN5 promoted cellulase production by driving H3ac modifications, and GCN5 directly band to the promoter regions to catalyze distinct H3ac modifications • SNF1 acts upstream of GCN5 as a transcriptional activator in the cellulase production of Trichoderma.

ß-Carotene extracted from Blakeslea trispora attenuates oxidative stress, inflammatory, hepatic injury and immune damage induced by copper sulfate in zebrafish (Danio rerio).

ß-Carotene, as a kind of potent antioxidant compounds, has gained extensive attention. Blakeslea trispora, a filiform aerobic fungus, has been proposed as a natural source of ß-carotene for commercial exploitation. However, it has not yet been investigated whether ß-carotene extracted from Blakeslea trispora can attenuate oxidative stress, inflammatory, liver injury and immune damage of zebrafish (Danio rerio) exposed to copper sulfate (CuSO4). In this study, we evaluated the effects of ß-carotene on migration of GFP-labeled neutrophils, histological changes of liver, markers of oxidative, inflammatory cytokines and transaminase analysis, as well as the expression and activities of apoptosis, immune-related certain genes in zebrafish treated with different concentrations of ß-carotene (0, 10, 20, 40 µg/mL) after exposure to CuSO4. The results indicated that ß-carotene reduced migration of neutrophils and released liver damage. What's more, ß-carotene was found to reduce the index levels of oxidative stress response (HMOX-1, reactive oxygen species (ROS), NADPH, MDA), inflammatory factors (interleukine-1ß (IL-1ß), interleukine-6 (IL-6), interleukine-8 (IL-8), tumor necrosis factor-α (TNF-α)), liver function protein (AST, ALT) which increased by CuSO4. ß-Carotene also promoted the activities of SOD, GSH-Px, ACP, AKP and LZM and increased the protein of immune-related factors, IgM and IFN-γ after exposure to CuSO4. Thus, our results demonstrate that ß-carotene has an antioxidant, anti-inflammatory and hepatoprotective activity and participation in immunoregulation.

Histone acetyltransferase GCN5-mediated lysine acetylation modulates salt stress aadaption of Trichoderma.

Trichoderma viride has a wide range of applications in plant growth promotion, biological control, cellulase production, and biomass utilization. Salinity is a major limitation to Trichoderma strains in the natural environment and fermentation environment, and to improve the adaptability of Trichoderma to salt stress is of great significance to its applications in industry and agriculture. Histone acetylation plays important roles in the regulation of physiological and biochemical processes including various stress responses. GCN5 is the most representative histone acetylase, which plays vital roles in chromatin remodeling of promoters to facilitate the transcription activation. In this paper, we identified a GCN5-encoding gene TvGCN5 in T. viride Tv-1511, and characterized the function and regulating mechanism of TvGCN5-mediated acetylation of histone H3 in the salt adoption of Tv-1511, by constructions of the deletion mutants (Tv-1511-△GCN5) and overexpression mutants (Tv-1511-GCN5-OE) of TvGCN5. Results showed that compared with wild-type Tv-1511, the over-expression of TvGCN5 resulted in the longer mycelia diameter and more biomass under salt stress. Furthermore, Tv-1511-△GCN5 strains obtained the improved sodium (Na+) compartmentation and antioxidant capacity by upregulating the transcriptional levels of genes encoding PM H+-ATPase, vacuolar H+-ATPase, and antioxidant enzymes. Notably, the changes in the transcriptional expressions of these genes are tightly modulated by the TvGCN5-mediated acetylated level of histone H3 in their promoter regions. In all, these results reveal that TvGCN5 plays an important role in stress tolerance of T. viride Tv-1511, and provides potential insight to facilitate the application of epigenetic modulation in the expanding utilization of Trichoderma. KEY POINTS: • Overexpresison of TvGCN5 improves the adoption of T. viride Tv-1511 to salt stress by increasing acetylation level of histone H3 on the promoter regions of sodium-transport and antioxidant-related genes, at H3K9ac, H3K14ac, H3K23ac, and H3K27ac. • Overexprsison of TvGCN5 enhances the ion transport and compartmentation capacity by upregulating the expressions and activities of PM and vacuolar H+-ATPase to tolerate salt stress. • Overexprsison of TvGCN5 promotes the antioxidant capacity by increasing the expressions and activities of antioxidant enzymes in response to salt stress.