Microviridin 1777: A Toxic Chymotrypsin Inhibitor Discovered by a Metabologenomic Approach


The toxicity of the cyanobacterium Microcystis aeruginosa EAWAG 127a was evaluated against the sensitive grazer Thamnocephalus platyurus, and the extract possessed strong activity. To investigate the compounds responsible for cytotoxicity, a series of peptides from this cyanobacterium were studied using a combined genomic and molecular networking approach. The results led to the isolation, structure elucidation, and biological evaluation of microviridin 1777, which represents the most potent chymotrypsin inhibitor characterized from this family of peptides to date. Furthermore, the biosynthetic gene clusters of microviridin, anabaenopeptin, aeruginosin, and piricyclamide were located in the producing organism, and six additional natural products were identified by tandem mass spectrometry analyses. These results highlight the potential of modern techniques for the identification of natural products, demonstrate the ecological role of protease inhibitors produced by cyanobacteria, and raise ramifications concerning the presence of novel, yet uncharacterized, toxin families in cyanobacteria beyond microcystin.

Full text of the study can be accessed at the website of the publisher (journal subscription is needed), or can be supplied on demand by email request to simon.sieber@uzh.ch


Simon Sieber, Simone M. Grendelmeier, Lonnie A. Harris, Douglas A. Mitchell, and Karl Gademann. Microviridin 1777: A Toxic Chymotrypsin Inhibitor Discovered by a Metabologenomic Approach. Journal of Natural Products. DOI: 10.1021/acs.jnatprod.9b00986

Keywords: Microviridin 1777, Toxic Compounds, Chymotrypsin Inhibitors, Metabologenomic Approach, Microcystin, Cytotoxicity,Thamnocephalus platyurus, Microcystis aeruginosa EAWAG 127a, Cyanobacteria, #NaturalProducts, #Peptides. 

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