Heterodimerization of Human UDP-Glucuronosyltransferase 1A9 and UDP-Glucuronosyltransferase 2B7 Alters Their Glucuronidation Activities

Jia Xue; Jiayi Yin; Jing Nie; Huidi Jiang; Haitao Zhang; Su Zeng

doi:10.1124/dmd.123.001369

Heterodimerization of Human UDP-Glucuronosyltransferase 1A9 and UDP-Glucuronosyltransferase 2B7 Alters Their Glucuronidation Activities

Drug Metab Dispos. 2023 Nov;51(11):1499-1507. doi: 10.1124/dmd.123.001369. Epub 2023 Aug 29.

Authors

Jia Xue¹, Jiayi Yin¹, Jing Nie¹, Huidi Jiang¹, Haitao Zhang², Su Zeng²

Affiliations

¹ Institute of Drug Metabolism and Pharmaceutical Analysis (J.X., J.Y., J.N., H.J., S.Z.) and Hangzhou Institute of Innovative Medicine, Institute of Pharmacology and Toxicology (H.Z.), Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Department of Pharmacy, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang, China (J.N.); and The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (H.Z.).
² Institute of Drug Metabolism and Pharmaceutical Analysis (J.X., J.Y., J.N., H.J., S.Z.) and Hangzhou Institute of Innovative Medicine, Institute of Pharmacology and Toxicology (H.Z.), Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Department of Pharmacy, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, Zhejiang, China (J.N.); and The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China (H.Z.) zengsu@zju.edu.cn haitaozhang@zju.edu.cn.

PMID: 37643881
DOI: 10.1124/dmd.123.001369

Abstract

Human UDP-glucuronosyltransferases (UGTs) play a pivotal role as prominent phase II metabolic enzymes, mediating the glucuronidation of both endobiotics and xenobiotics. Dimerization greatly modulates the enzymatic activities of UGTs. In this study, we examined the influence of three mutations (H35A, H268Y, and N68A/N315A) and four truncations (signal peptide, single transmembrane helix, cytosolic tail, and di-lysine motif) in UGT2B7 on its heterodimerization with wild-type UGT1A9, using a Bac-to-Bac expression system. We employed quantitative fluorescence resonance energy transfer (FRET) techniques and co-immunoprecipitation assays to evaluate the formation of heterodimers between UGT1A9 and UGT2B7 allozymes. Furthermore, we evaluated the glucuronidation activities of the heterodimers using zidovudine and propofol as substrates for UGT2B7 and UGT1A9, respectively. Our findings revealed that the histidine residue at codon 35 was involved in the dimeric interaction, as evidenced by the FRET efficiencies and catalytic activities. Interestingly, the signal peptide and single transmembrane helix domain of UGT2B7 had no impact on the protein-protein interaction. These results provide valuable insights for a comprehensive understanding of UGT1A9/UGT2B7 heterodimer formation and its association with glucuronidation activity. SIGNIFICANCE STATEMENT: Our findings revealed that the H35A mutation in UGT2B7 affected the affinity of protein-protein interaction, leading to discernable variations in fluorescence resonance energy transfer efficiencies and catalytic activity. Furthermore, the signal peptide and single transmembrane helix domain of UGT2B7 did not influence heterodimer formation. These results provide valuable insights into the combined effects of polymorphisms and protein-protein interactions on the catalytic activity of UGT1A9 and UGT2B7, enhancing our understanding of UGT dimerization and its impact on metabolite formation.