Increased activity of the sterol branch of the mevalonate pathway elevates glycosylation of secretory proteins and improves antifungal properties of Trichoderma atroviride

Integrated Transcriptome and Untargeted Metabolomic Analyses Revealed the Role of Methyltransferase Lae1 in the Regulation of Phospholipid Metabolism in Trichoderma atroviride

The putative methyltransferase Lae1 is a global regulator in Trichoderma, which modulates the expression of secondary metabolite gene clusters, possibly via chromatin remodeling. Here we aimed to explore the specific transcription and metabolites profiles regulated by Lae1 in T. atroviride 23. Comparative transcriptomics and metabolome analyses between the lae1 deletion (Mlae1) and over-expressing (Olae1) mutants were performed using RNA sequencing and QTOF-UPLC-MS techniques. In total, 1344 unique differentially expressed genes (DEGs) and 92 metabolites were identified across three strains. The significantly altered metabolic profiles revealed that the lae1 gene modulates central carbon metabolism, amino acid metabolism, secondary metabolism, and phospholipid metabolism. The effects of lae1 on phospholipid metabolism were further explored, and the findings showed that lae1 modulates the composition and function of cell membranes and other metabolic activities, including the phosphotransferase system (PTS) and biosynthesis of secondary metabolites (SM). Phospholipid metabolism is related to energy metabolism, signal transduction, and environmental adaptability of microorganisms. These data showed that Lae1 affects the primary metabolites, phospholipid, as well as the regulation of secondary metabolites in Trichoderma. This study could potentially provoke in-depth investigations of the Lae1-mediated target genes in phospholipid synthesis. The Lae1 may act as a novel target that is associated with disease defense and drug development in the future.

Expression of Saccharomyces cerevisiae RER2 Gene Encoding Cis-Prenyltransferase in Trichoderma atroviride Increases the Activity of Secretory Hydrolases and Enhances Antimicrobial Features

Some Trichoderma spp. exhibit natural abilities to reduce fungal diseases of plants through their mycoparasitic and antagonistic properties. In this study, we created new Trichoderma atroviride strains with elevated antifungal activity. This effect was achieved by improving the activity of cis-prenyltransferase, the main enzyme in dolichol synthesis, by expressing the RER2 gene from Saccharomyces cerevisiae. Since dolichyl phosphate is the carrier of carbohydrate residues during protein glycosylation, activation of its synthesis enhanced the activities of dolichyl-dependent enzymes, DPM synthase and N-acetylglucosamine transferase, as well as stimulated glycosylation of secretory proteins. Cellulases secreted by the transformants revealed significantly higher levels or activities compared to the control strain. Consequently, the resulting Trichoderma strains were more effective against the plant pathogens Pythium ultimum.