Microbial Communication and Natural Products
Fungi are producing numerous secondary metabolites ‒ natural products ‒ which often are biologically active. Well known examples include the antibiotic penicillin, the mycotoxin aflatoxin or the immunosuppressant cyclosporin. It is assumed that these compounds play a crucial role in microbial communication. Hence, the elucidation of these specific communications is one of the emerging fields in microbiology and chemical biology. We have discovered that the intimate physical contact between the Gram-positive bacterium Streptomyces rapamycinicus with either A. nidulans or A. fumigatus leads to the activation of silent gene clusters in both fungi. For A. nidulans we demonstrated that the bacterium is able to reprogram the histone modification machinery of the fungus via manipulation of the SAGA-ADA complex. SAGA-ADA contains the GCN5 histone acetyl transferase, which acetylates the lysine residues K9 and K14 of histone 3, which leads to the activation of the silent orsellinic acid gene cluster. This excellent model system will allow fundamental insights into epigenetic regulation of secondary metabolites in response to microbial communication and into entirely novel molecular mechanisms of epigenetic control of gene clusters. Moreover, it is suitable to prove the novel concept that interaction-driven production of novel compounds affects the structuring of microbial communities
Another interesting interaction is formed by Aspergillus fumigatus with Pseudomonas aeruginosa. Both microorganisms are regularly found in the lungs of patients with cystic fibrosis (CF). The meaning of this interaction for the progression of disease is unclear. Therefore, we have been studying the interaction at molecular level.