Possible involvement of G-proteins and cAMP in the induction of progesterone hydroxylating enzyme system in the vascular wilt fungus Fusarium oxysporum |
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Authors: | Anna Poli Antonio Di Pietro Dusan Zigon Helena Lenasi |
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Affiliation: | aInstitute of Biochemistry, Faculty of Medicine, University of Ljubljana, Vrazov Trg 2, 1000 Ljubljana, Slovenia;bDepartamento de Genetica, Universidad de Cordoba, Campus de Rabanales Edificio C5, 14071 Cordoba, Spain;cDepartment of Mass Spectrometry, Institute Jožef Stefan, Jamova Ulica 39, 1000 Ljubljana, Slovenia |
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Abstract: | Fungi present the ability to hydroxylate steroids. In some filamentous fungi, progesterone induces an enzyme system which converts the compound into a less toxic hydroxylated product. We investigated the progesterone response in the vascular wilt pathogen Fusarium oxysporum, using mass spectrometry and high performance liquid chromatography (HPLC). Progesterone was mainly transformed into 15α-hydroxyprogesterone, which was found predominantly in the extracellular medium. The role of two conserved fungal signaling cascades in the induction of the progesterone-transforming enzyme system was studied, using knockout mutants lacking the mitogen-activated protein kinase Fmk1 or the heterotrimeric G-protein β subunit Fgb1 functioning upstream of the cyclic adenosine monophosphate (cAMP) pathway. No steroid hydroxylation was induced in the Δfgb1 strain, suggesting a role for the G-protein β subunit in progesterone signaling. Exogenous cAMP restored the induction of progesterone-transforming activity in the Δfgb1 strain, suggesting that steroid signaling in F. oxysporum is mediated by the cAMP-PKA pathway. |
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Keywords: | Fusarium oxysporum Progesterone Steroid hydroxylation Detoxification Mitogen-activated protein kinase (MAPK) G-protein β subunit cAMP |
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