Submitted to: Phytochemical Society of North America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 29, 2004
Publication Date: July 29, 2004
Citation: Mc Cormick, S.P., Alexander, N.J., Proctor, R. 2004. Heterologous expression of two fusarium trichothecene p450 genes. Phytochemical Society of North America Proceedings. Technical Abstract: Fusarium graminearum and F. sporotrichioides produce the trichothecene mycotoxins 15-acetyldeoxynivalenol and T-2 toxin, respectively. In both species, disruption of the P450 monooxygenase-encoding gene Tri4 blocks production of the mycotoxins and leads to the accumulation of the trichothecene precursor trichodiene. To further characterize its function, the F. graminearum Tri4 (FgTri4) was heterologously expressed in the trichothecene-nonproducing species F. verticillioides. Transgenic F. verticillioides carrying the FgTri4 converted exogenous trichodiene to the trichothecene biosynthetic intermediate isotrichodermin. Conversion of trichodiene to isotrichodermin requires seven steps, two of which can occur non-enzymatically. Precursor feeding studies done in the current study indicate that wild-type F. verticillioides has the enzymatic activity necessary to carry out the seventh step, the C-3-acetylation of isotrichodermol to form isotrichodermin. Together, the results of this study suggest that the Tri4 protein catalyzes the remaining four steps and is therefore a multifunctional monooxygenase. We also used this approach to look at oxygenation steps near the end of the biosynthetic pathway controlled by Tri1.