中文摘要：玉米赤霉烯酮（ZEN）是一种雌激素性霉菌毒素，存在于镰刀菌感染的谷物中。糖基化是一种重要的植物防御机制并通常能降低霉菌毒素对人和动物的急性毒性。ZEN糖苷的毒理学资料因无法满足研究所需的极大的动物量而有限。在大肠杆菌中表达、亲和纯化并表征了HvUGT14077，一种最近确认的能结合ZEN的大麦UDP葡糖基转移酶。HvUGT14077对ZEN具有高亲和力(Km = 3_M)及高催化效率(kcat/Km = 190 s 1_mM 1)。
外文摘要：Zearalenone (ZEN) is an estrogenic mycotoxin occurring in Fusarium-infected cereals. Glucosylation is an important plant defense mechanism and generally reduces the acute toxicity of mycotoxins to humans and animals. Toxicological information about ZEN-glucosides is limited due to the unavailability of larger amounts required for animal studies. HvUGT14077, a recently-validated ZEN-conjugating barley UDP-glucosyltransferase was expressed in Escherichia coli, affinity purified, and characterized. HvUGT14077 possesses high affinity (Km = 3 _M) and catalytic efficiency (kcat/Km = 190 s1_mM1) with ZEN. It also efficiently glucosylates the phase-I ZEN-metabolites _-zearalenol and _-zearalenol, with kcat/Km of 40 and 74 s1_mM1, respectively. HvUGT14077 catalyzes O-glucosylation at C-14 and C-16 with preference of 14-glucoside synthesis. Furthermore, relatively slow consecutive formation of 14,16-di-glucosides was observed; their structures were tentatively identified by mass spectrometry and for ZEN-14,16-di-glucoside confirmed by nuclear magnetic resonance spectroscopy. Recombinant HvUGT14077 allowed efficient preparative synthesis of ZEN-glucosides, yielding about 90% ZEN-14-glucoside and 10% ZEN-16-glucoside. The yield of ZEN-16-glucoside could be increased to 85% by co-incubation with a _-glucosidase highly selective for ZEN-14-glucoside. Depletion of the co-substrate UDP-glucose was counteracted by a sucrose synthase based regeneration system. This strategy could also be of interest to increase the yield of minor glucosides synthesized by other glucosyltransferases.
外文关键词：zearalenone-14-glucoside；zearalenone-16-glucoside；masked mycotoxin；glycosylation；sucrose synthase；secondary metabolite
作者：Michlmayr, H；Varga, E；Lupi, F；Malachova, A；Hametner, C；Berthiller, F；Adam, G
作者单位：Univ Nat Resources & Life Sci
期刊名称：TOXINS
期刊影响因子：3.571
出版年份：2017
出版刊次：2
点击下载：利用重组的大麦糖基转移酶HvUGT14077合成玉米赤霉烯酮单糖苷和二苷以及α/β-玉米赤霉烯