Submitted to: Phytochemical Society of North America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 3, 2005
Publication Date: August 3, 2005
Citation: Mc Cormick, S.P., Alexander, N.J., Proctor, R. 2005. Heterologous expression of fusarium trichothecene p450 genes [abstract]. Phytochemical Society of North America Proceedings. p. 68. 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. 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. The results of this study suggest that the FgTri4 protein catalyzes the first four oxygenation steps. We used heterologous expression to look at oxygenation steps near the end of the biosynthetic pathway controlled by Tri1. Experiments confirmed that FsTri1 controls C-8 hydroxylation but showed that FgTri1 controls both C-7 and C-8 hydroxylation. We also found that although wild-type F. verticillioides produces no trichothecenes it is capable of trichothecene C-3 acetylation, C-4 or C-15 deacetylation and C-8 oxidation.