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Hydroxylations of trichothecene rings in the biosynthesis of Fusarium trichothecenes: evolution of alternative pathways in the nivalenol chemotype
Author(s) -
Maeda Kazuyuki,
Tanaka Akira,
Sugiura Ryosuke,
Koshino Hiroyuki,
Tokai Takeshi,
Sato Masayuki,
Nakajima Yuichi,
Tanahashi Yoshikazu,
Kanamaru Kyoko,
Kobayashi Tetsuo,
Nishiuchi Takumi,
Fujimura Makoto,
TakahashiAndo Naoko,
Kimura Makoto
Publication year - 2016
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.13338
Subject(s) - trichothecene , hydroxylation , biology , monooxygenase , cytochrome p450 , chemotype , biosynthesis , mutant , fusarium , metabolite , gene , biochemistry , stereochemistry , enzyme , genetics , botany , chemistry , essential oil
Summary F usarium s porotrichioides genes FsTri11 , FsTri13 , and FsTri1 encode cytochrome P450 monooxygenases (CYPs) responsible for hydroxylations at C‐15, C‐4, and C‐8 of the trichothecene skeleton, respectively. However, the corresponding genes of nivalenol (NIV)‐chemotype Fusarium graminearum remain to be functionally elucidated. In this study, we characterized the roles of these CYPs in NIV biosynthesis. Analyses of the metabolites of the F . g raminearum Fgtri11 − mutant, a disruptant of FgTri11 encoding isotrichodermin (ITD) C‐15 hydroxylase, revealed a small amount of NIV‐type trichothecenes suggesting that an alternative C‐15 hydroxylase partially complemented FgTRI11p. In contrast, the C‐7/C‐8 hydroxylations depended solely on FgTRI1p, as suggested by the metabolite profiles of the Fgtri11 − Fgtri1 − double gene disruptant. Disruption of FgTri1 in both the wild‐type and Fgtri13 − mutant backgrounds revealed that FgTRI13p exhibits marginal activity toward calonectrin (CAL) and that it was the only C‐4 hydroxylase. In addition, feeding experiments demonstrated that the C‐4 hydroxylation of a 7‐hydroxytrichothecene lacking C‐8 ketone was extremely limited. The marginal activity of FgTRI13p toward CAL was advantageous for the C‐7/C‐8 hydroxylation steps in NIV biosynthesis, as transformation of a C‐4 oxygenated trichothecene lacking C‐7/C‐8 modifications into NIV‐type trichothecenes was quite inefficient. The significance of hydroxylation steps in the evolution of Fusarium trichothecenes is discussed.