Nanoscale enrichment of the cytosolic enzyme trichodiene synthase near reorganized endoplasmic reticulum in Fusarium graminearum

Authors: BOENISCH, MARIKE - University Of Minnesota; BLUM, AILISA - Commonwealth Scientific And Industrial Research Organisation (CSIRO); Broz, Karen; GARDINER, DONALD - Commonwealth Scientific And Industrial Research Organisation (CSIRO); Kistler, Harold

Submitted to: Fungal Genetics and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2018
Publication Date: 3/1/2019
Citation: Boenisch, M.J., Blum, A., Broz, K.L., Gardiner, D.M., Kistler, H.C. 2019. Nanoscale enrichment of the cytosolic enzyme trichodiene synthase near reorganized endoplasmic reticulum in Fusarium graminearum. Fungal Genetics and Biology. 124:73-77. https://doi.org/10.1016/j.fgb.2018.12.008.
DOI: https://doi.org/10.1016/j.fgb.2018.12.008

Interpretive Summary: Molds infest cereal crops with harmful metabolites called mycotoxins. Mycotoxins are important risks to the health of humans and livestock. We seek to understand how these toxins are produced in grain in order to develop measures to minimize toxin contamination. This manuscript describes the precise cellular location of one fungal enzyme which assembles the mycotoxin known as vomitoxin. This information is important for understanding how fungal metabolites are produced and how mycotoxins accumulate in grain and the environment. The study concludes that mycotoxin synthesis requires particular subcellular structures that may be targeted for reduction of vomitoxin synthesis. This information will be helpful to develop novel strategies to control contamination of grain with these toxins.

Technical Abstract: Trichothecene mycotoxin synthesis in the phytopathogen Fusarium graminearum, involves primarily endoplasmic reticulum (ER)-localized enzymes of the mevalonate- and trichothecene biosynthetic pathways. Two exceptions are 3-hydroxy-3-methylglutaryl CoA synthase (Hms1) and trichodiene synthase (Tri5) which are known cytosolic enzymes. Using 3D structured illumination microscopy (3D SIM), GFP-tagged Tri5 and Hms1 were tested for preferential localization in the cytosol proximal to the ER. Tri5 protein was significantly enriched in cytosolic regions within 500 nm of the ER, but Hms1 was not. Spatial organization of enzymes in the cytosol has potential relevance for pathway efficiency and metabolic engineering in fungi and other organisms.