Priest David M, Jackson Rosamond G, Ashford David A, Abrams Suzanne R, Bowles Dianna J
CNAP, Department of Biology (Area 8), University of York, York YO10 5YW, United Kingdom.
FEBS Lett. 2005 Aug 15;579(20):4454-8. doi: 10.1016/j.febslet.2005.06.084.
This study analyses the activity of an Arabidopsis thaliana UDP-glycosyltransferase, UGT71B6 (71B6), towards abscisic acid (ABA) and its structural analogues. The enzyme preferentially glucosylated ABA and not its catabolites. The requirement for a specific chiral configuration of (+)-ABA was demonstrated through the use of analogues with the chiral centre changed or removed. The enzyme was able to accommodate extra bulk around the double bond of the ABA ring but not alterations to the 8'- and 9'-methyl groups. Interestingly, the ketone of ABA was not required for glucosylation. Bioactive analogues, resistant to 8'-hydroxylation, were also poor substrates for conjugation by UGT71B6. This suggests the compounds may be resistant to both pathways of ABA inactivation and may, therefore, prove to be useful agrochemicals for field applications.
本研究分析了拟南芥UDP-糖基转移酶UGT71B6（71B6）对脱落酸（ABA）及其结构类似物的活性。该酶优先将ABA糖基化，而非其分解代谢产物。通过使用手性中心改变或去除的类似物，证明了对（+）-ABA特定手性构型的需求。该酶能够容纳ABA环双键周围的额外基团，但不能接受8'-和9'-甲基的改变。有趣的是，ABA的酮基并非糖基化所必需。对8'-羟基化具有抗性的生物活性类似物，也是UGT71B6进行缀合反应的不良底物。这表明这些化合物可能对ABA失活的两条途径均具有抗性，因此可能被证明是适用于田间应用的有用农用化学品。
