Institute of Drug Metabolism and Pharmaceutical Analysis, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China.
Sci Rep. 2016 Nov 18;6:34450. doi: 10.1038/srep34450.
Human UDP-glucuronosyltransferases (UGTs) play a pivotal role in phase II metabolism by catalyzing the glucuronidation of endobiotics and xenobiotics. The catalytic activities of UGTs are highly impacted by both genetic polymorphisms and oligomerization. The present study aimed to assess the inter-isoform hetero-dimerization of UGT1A1, 1A9, and 2B7, including the wild type (1A11, 1A91, and 2B71) and the naturally occurring (1A11b, 1A9*2/*3/5, and 2B771S/*2/*5) variants. The related enzymes were double expressed in Bac-to-Bac systems. The fluorescence resonance energy transfer (FRET) technique and co-immunoprecipitation (Co-IP) revealed stable hetero-dimerization of UGT1A1, 1A9, and 2B7 allozymes. Variable FRET efficiencies and donor-acceptor distances suggested that genetic polymorphisms resulted in altered affinities to the target protein. In addition, the metabolic activities of UGTs were differentially altered upon hetero-dimerization via double expression systems. Moreover, protein interactions also changed the regioselectivity of UGT1A9 for querectin glucuronidation. These findings provide in-depth understanding of human UGT dimerization as well as clues for complicated UGT dependent metabolism in humans.
人类尿苷二磷酸葡萄糖醛酸转移酶（UGTs）通过催化内源性和外源性物质的葡萄糖醛酸化，在 II 相代谢中发挥关键作用。UGTs 的催化活性受到遗传多态性和寡聚化的强烈影响。本研究旨在评估 UGT1A1、1A9 和 2B7 的同工型间异源二聚化，包括野生型（1A11、1A91 和 2B71）和天然存在的（1A11b、1A9*2/*3/5 和 2B771S/*2/*5）变体。相关酶在 Bac-to-Bac 系统中双表达。荧光共振能量转移（FRET）技术和共免疫沉淀（Co-IP）揭示了 UGT1A1、1A9 和 2B7 同工型的稳定异源二聚化。可变的 FRET 效率和供体-受体距离表明遗传多态性导致与靶蛋白的亲和力发生改变。此外，通过双表达系统，UGTs 的代谢活性在异源二聚化后发生了差异变化。此外，蛋白质相互作用也改变了 UGT1A9 对槲皮素葡萄糖醛酸化的区域选择性。这些发现深入了解了人类 UGT 二聚化以及人类复杂的 UGT 依赖性代谢的线索。
