Ribosomally synthesized and post-translationally modified peptides in trichoderma reesei: expression profiling and gene deletion

Abstract

Ribosomally Synthesized and Post-translationally Modified Peptides (RiPPs) are a class of secondary metabolites showing unique structural diversity and bioactive properties. In drug development approaches, they gain increasing attention as promising alternatives to conventional antibiotics.Several biosynthetic gene clusters containing putative RiPPs have been identified in the genomes of Trichoderma species. This thesis comprises the expression analysis of RiPP precursors and related biosynthetic genes in T. reesei, a filamentous fungus prominent in the industrial production of cellulases. In a first characterization attempt, relative transcript levels of selected genes were measured via RT-qPCR in order to estimate their biological functions. It could be shown that RiPPs in T. reesei are transcribed under various cultivation conditions, including exposure to different chemical and biological stress factors.Additionally, deletion strains were constructed to set a basis for elucidation of RiPP synthesis pathways. In total, one RiPP deletion strain as well as three individual deletion strains for biosynthetic genes were developed by double cross-over homologous recombination.Accompanied by the determined expression profiles, hereby constructed strains will help to confirm the presence of RiPPs in T. reesei and shed light on their structures and functions through future metabolic studies. That way, it will be found out whether RiPP natural products have the potential to avert the upcoming antimicrobial resistance crisis.