Structure, function, and inhibition of drug reactivating human gut microbial β-glucuronidases
Structure, function, and inhibition of drug reactivating human gut microbial β-glucuronidases
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DOI：
10.1038/s41598-018-36069-w
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发表时间：
2019-01-29
影响因子：
4.6
通讯作者：
Redinbo, Matthew R.
中科院分区：
文献类型：
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作者：
Biernat, Kristen A.;Pellock, Samuel J.;Redinbo, Matthew R.
细菌β-葡萄糖醛酸苷酶(GUS)通过逆转胃肠道中的第二阶段葡萄糖醛酸化作用而引起药物毒性。虽然许多人体肠道微生物GUS酶已经用模型葡萄糖醛酸化物底物(如p-硝基苯酚-β-D-葡萄糖醛酸化物(PNPG))进行了检测，但在处理药物-葡萄糖醛酸化物方面最有效的GUS同源物仍不清楚。在这里，我们介绍了来自人类肠道共生菌鼠李糖乳杆菌、瘤胃球菌和普氏杆菌的GUS酶的晶体结构，这些酶具有与处理药物底物的大肠杆菌GUS相似的活性位点环(环1；L1)。我们还解析了杜氏杆菌中的No Loop Gus的结构。然后，我们比较了一组12种结构不同的GUS蛋白的pNPG和双氯芬酸葡萄糖醛酸苷的处理能力，发现这里提出的新的L1 GUS酶处理小葡萄糖醛酸底物的效率低于以前表征的L1 GUS酶，如E.coliGUS。我们进一步证明，我们的GUS抑制剂对某些L1酶有效，但对所有酶都不有效。我们的发现准确地指出了药物-葡萄糖醛酸苷底物加工所必需的活性部位结构特征以及这种加工的抑制。
Bacterial beta-glucuronidase (GUS) enzymes cause drug toxicity by reversing Phase II glucuronidation in the gastrointestinal tract. While many human gut microbial GUS enzymes have been examined with model glucuronide substrates like p-nitrophenol-beta-D-glucuronide (pNPG), the GUS orthologs that are most efficient at processing drug-glucuronides remain unclear. Here we present the crystal structures of GUS enzymes from human gut commensals Lactobacillus rhamnosus, Ruminococcus gnavus, and Faecalibacterium prausnitzii that possess an active site loop (Loop 1; L1) analogous to that found in E. coli GUS, which processes drug substrates. We also resolve the structure of the No Loop GUS from Bacteroides dorei. We then compare the pNPG and diclofenac glucuronide processing abilities of a panel of twelve structurally diverse GUS proteins, and find that the new L1 GUS enzymes presented here process small glucuronide substrates inefficiently compared to previously characterized L1 GUS enzymes like E. coli GUS. We further demonstrate that our GUS inhibitors, which are effective against some L1 enzymes, are not potent towards all. Our findings pinpoint active site structural features necessary for the processing of drug-glucuronide substrates and the inhibition of such processing.