Karimi Aghcheh, R. (2009). LAE1 : a regulator of Trichoderma reesei secondary metabolism and sporulation [Diploma Thesis, Technische Universität Wien]. reposiTUm. http://hdl.handle.net/20.500.12708/186629
The filamentous fungus Trichoderma reesei is well known for its production different types of peptaibols which are considered a unique class of antibiotics being rich in the non-proteinogenic alfa-aminoisobutyric acid (Aib) and having an N-acyl (usually acetyl) terminus, and a C-terminal amino alcohol, such as phenylalaninol or leucinol. Production of peptaibols is still hampered by the poor information about the regulation of their biosynthesis, however. In Aspergillus spp., the laeA (loss of aflR expression) gene encodes a protein-methyltransferase that acts as global regulator of secondary metabolism. In this study, the LaeA orthologue of T. reesei (Lae1) has been identified by a phylogenetic approach. To elucidate a possible regulation of T. reesei peptaibol production by LAE1, we deleted the lae1 gene. To this end, a knock-out vector containing 1kb upstream and 1kb downstream non-coding regions of lae1 interrupted by the pyr4 (encoding the orotidine 5'-monophosphate decarboxylase required for pyrimidine biosynthesis) selection marker was constructed.<br />Transformation of the delta-lae1pyr4 deletion cassette into the KU70 negative T. reesei strain resulted in a number of lae1 deleted strains which was confirmed by diagnostic PCR. Analysis of the phenotype of these strains showed that LAE1 has a positive regulatory role in pigment formation and sporulation. Intact-cell Matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis of strains deleted in lae1, showed an impairment of formation of the 20-residues long peptaibols, from the paracelsins type, and of the 11-residues peptaibols, from the trichovorin/trickorozin type in the delta lae1 strains. The expression level of tpc1 and tps1 genes encoding peptaibol synthase of the paracelsin type and of the trichovorin type respectively showed that the lae1 knock-out causes partial loss of tpc1 and tps1 transcription in comparison with the parent strain. The results suggest that the LAE1, could considered as a regulator of the expression of secondary metabolite genes including peptaibols and sporulation.