Biochemical and biophysical characterization of a novel fumonisin detoxifying enzyme from Aspergillus niger

Fumonisins are toxic secondary metabolites produced by pathogenic fungi that infect crops. Ingestion of fumonisin contaminated feed can significantly decrease the health of livestock. Fumonisins are reduced linear polyketides that contain a primary amine and act as competitive inhibitors of ceramide synthase. Novel mechanisms to mitigate fumonisin toxicity are needed. The Garnham and Sumarah labs identified a novel enzyme from Aspergillus niger capable of detoxifying fumonisins by replacing the primary amine with a ketone. In my thesis, I biochemically and biophysically characterized a recombinant version of this fumonisin amine oxidase, termed AnFAO. By solving AnFAO’s X-ray crystal structure and developing spectrophotometric and mass spectrometry assays, I was able to better understand how AnFAO functions at the molecular level to deaminate fumonisins. AnFAO’s characterization allowed for identification of variants with enhanced activity towards fumonisins. These studies will inform how best to deploy AnFAO for remediation of fumonisin contaminated food and feed