Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, (BOKU), Konrad Lorenz Str. 24, 3430 Tulln, Austria.
Department of Food Chemistry and Toxicology, University of Vienna, Währinger Str. 38, 1090 Vienna, Austria.
Toxins (Basel). 2018 Mar 6;10(3):111. doi: 10.3390/toxins10030111.
Trichothecene toxins are confirmed or suspected virulence factors of various plant-pathogenic species. Plants can detoxify these to a variable extent by glucosylation, a reaction catalyzed by UDP-glucosyltransferases (UGTs). Due to the unavailability of analytical standards for many trichothecene-glucoconjugates, information on such compounds is limited. Here, the previously identified deoxynivalenol-conjugating UGTs HvUGT13248 (barley), OsUGT79 (rice) and Bradi5g03300 (), were expressed in , affinity purified, and characterized towards their abilities to glucosylate the most relevant type A and B trichothecenes. HvUGT13248, which prefers nivalenol over deoxynivalenol, is also able to conjugate C-4 acetylated trichothecenes (e.g., T-2 toxin) to some degree while OsUGT79 and Bradi5g03300 are completely inactive with C-4 acetylated derivatives. The type A trichothecenes HT-2 toxin and T-2 triol are the kinetically preferred substrates in the case of HvUGT13248 and Bradi5g03300. We glucosylated several trichothecenes with OsUGT79 (HT-2 toxin, T-2 triol) and HvUGT13248 (T-2 toxin, neosolaniol, 4,15-diacetoxyscirpenol, fusarenon X) in the preparative scale. NMR analysis of the purified glucosides showed that exclusively β-D-glucosides were formed regio-selectively at position C-3-OH of the trichothecenes. These synthesized standards can be used to investigate the occurrence and toxicological properties of these modified mycotoxins.
单端孢霉烯族毒素是各种植物病原种的确认或疑似毒力因子。植物可以通过葡糖基化在一定程度上解毒这些毒素，葡糖基化反应由 UDP-葡糖基转移酶（UGTs）催化。由于许多单端孢霉烯族葡糖苷的分析标准不可用，因此有关这些化合物的信息有限。在这里，先前鉴定的结合去氧雪腐镰刀菌烯醇的 UGTs HvUGT13248（大麦）、OsUGT79（水稻）和 Bradi5g03300（）在 中表达，亲和纯化，并针对其将最相关的类型 A 和 B 单端孢霉烯族毒素葡糖基化的能力进行了表征。HvUGT13248 更喜欢结合去氧雪腐镰刀菌烯醇而不是结合脱氧雪腐镰刀菌烯醇，也能够在一定程度上结合 C-4 乙酰化的单端孢霉烯族毒素（例如，T-2 毒素），而 OsUGT79 和 Bradi5g03300 则完全不与 C-4 乙酰化衍生物结合。对于 HvUGT13248 和 Bradi5g03300，HT-2 毒素和 T-2 三醇是动力学上更优先的底物。我们用 OsUGT79（HT-2 毒素，T-2 三醇）和 HvUGT13248（T-2 毒素，新茄病镰刀菌醇，4,15-二乙酰基雪腐镰刀菌烯醇，呋咱烯酮 X）在制备规模上对几种单端孢霉烯族毒素进行了葡糖基化。对纯化的葡糖苷进行 NMR 分析表明，仅在单端孢霉烯族毒素的 C-3-OH 位置以区域选择性方式形成了β-D-葡糖苷。这些合成的标准品可用于研究这些修饰的霉菌毒素的发生和毒理学特性。
