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Updated: Aug 14, 2026
Genetic Manipulation of the Plant Pathogen Ustilago maydis to Study Fungal Biology and Plant Microbe Interactions
Published on: September 30, 2016
Expression, purification, reconstitution and inhibition of Ustilago maydis sterol 14 alpha-demethylase (CYP51;
D C Lamb1, D E Kelly, N J Manning
1Institute of Biological Sciences, University of Wales Aberystwyth, UK.
Abstract:
Triadimenol and tebuconazole are potent inhibitors of the sterol 14 alpha-demethylation reaction in fungi which is catalysed by CYP51, a haem-thiolate containing enzyme belonging to the cytochrome P450 monooxygenase superfamily. Using CYP51 from the phytopathogen Ustilago maydis, a comparison of the sensitivity of the fungal enzyme to triadimenol and tebuconazole has been carried out. U. maydis CYP51 was purified to homogeneity as determined by SDS-PAGE and specific haem content. Catalytic activity was investigated following reconstitution with its respective NADPH cytochrome P450 reductase and proposed endogenous substrate, 24-methylenedihydrolanosterol. Addition of the triadimenol and tebuconazole induced type II spectral changes in the enzyme, with saturation occurring at equimolar azole concentrations. Inhibition of reconstituted activities showed a one-to-one sensitivity of the fungal CYP51 as judged by IC50 values. The implications for fungicide mode of action and treatment are discussed.
