中文摘要：赤霉病是一种对农业和人类健康影响显著的植物病害，对小麦、大麦和玉米等谷类作用具有影响，其特点在于导致谷物产量减少和单端孢霉烯真菌毒素（如脱氧雪腐镰刀菌烯醇（DON））累积。已有研究单端孢霉烯产物是禾谷镰刀菌的毒力因子，而且DON抗性与小麦形成DON-3-O-葡萄糖苷的能力有关。本研究中，报道了一种来自水稻的脱氧雪腐镰刀菌烯醇（UDP-葡糖基转移酶 (Os79)）的结构。本研究所得的数据为理解此酶的底物特异性和活性奠定了基础，可用于指导今后谷类作物DON抗性的提升。
外文摘要：Fusarium head blight is a plant disease with significant agricultural and health impact which affects cereal crops such as wheat, barley, and maize and is characterized by reduced grain yield and the accumulation of trichothecene mycotoxins such as deoxynivalenol (DON). Studies have identified trichothecene production as a virulence factor in Fusarium graminearum and have linked DON resistance to the ability to form DON-3-O-glucoside in wheat. Here, the structures of a deoxynivalenol:UDP-glucosyltransferase (Os79) from Oryza sativa are reported in complex with UDP in an open conformation, in complex with UDP in a closed conformation, and in complex with UDP-2-fluoro-2-deoxy-d-glucose and trichothecene at 1.8, 2.3, and 2.2 Å resolution, respectively. The active site of Os79 lies in a groove between the N-terminal acceptor and the C-terminal donor-binding domains. Structural alignments reveal that Os79 likely utilizes a catalytic mechanism similar to those of other plant UGTs, with His 27 activating the trichothecene O3 hydroxyl for nucleophilic attack at C1′ of the UDP-glucose donor. Kinetic analysis of mutant Os79 revealed that Thr 291 plays a critical role in catalysis as a catalytic acid or to position the UDP moiety during the nucleophilic attack. Steady-state kinetic analysis demonstrated that Os79 conjugates multiple trichothecene substrates such as DON, nivalenol, isotrichodermol, and HT-2 toxin, but not T-2 toxin. These data establish a foundation for understanding substrate specificity and activity in this enzyme and can be used to guide future efforts to increase DON resistance in cereal crops.
外文关键词：GLUCOSE ANTHOCYANIDIN 3-O-GLUCOSYLTRANSFERASE; FUSARIUM-GRAMINEARUM; MEDICAGO-TRUNCATULA; FUNCTIONAL-CHARACTERIZATION; TRICHOTHECENE BIOSYNTHESIS; MYCOTOXIN DEOXYNIVALENOL; HETEROLOGOUS EXPRESSION; CLITORIA-TERNATEA; GLYCOSYLTRANSFERASES; BARLEY
作者：Wetterhorn, Karl M.; Newmister, Sean A.; Caniza, Rachell K.; Busman, Mark; McCormick, Susan P.; Berthiller, Franz; Adam, Gerhard; Rayment, Ivan
作者单位：Univ Wisconsin,USA
期刊名称：BIOCHEMISTRY
期刊影响因子：2.876
出版年份：2016
出版刊次：11
点击下载：水稻Os79 (Os04g0206600)的晶体结构：与脱氧雪腐镰刀菌烯醇脱毒有关的UDP葡糖基转移酶