Department of Biochemistry, Duke University Medical Center, Durham, NC, USA.
Faculty of Pharmaceutical Science, Hokkaido University, Sapporo, Japan.
Nat Struct Mol Biol. 2018 Mar;25(3):217-224. doi: 10.1038/s41594-018-0031-y. Epub 2018 Feb 19.
N-linked glycosylation is a predominant post-translational modification of protein in eukaryotes, and its dysregulation is the etiology of several human disorders. The enzyme UDP-N-acetylglucosamine:dolichyl-phosphate N-acetylglucosaminephosphotransferase (GlcNAc-1-P-transferase or GPT) catalyzes the first and committed step of N-linked glycosylation in the endoplasmic reticulum membrane, and it is the target of the natural product tunicamycin. Tunicamycin has potent antibacterial activity, inhibiting the bacterial cell wall synthesis enzyme MraY, but its usefulness as an antibiotic is limited by off-target inhibition of human GPT. Our understanding of how tunicamycin inhibits N-linked glycosylation and efforts to selectively target MraY are hampered by a lack of structural information. Here we present crystal structures of human GPT in complex with tunicamycin. Structural and functional analyses reveal the difference between GPT and MraY in their mechanisms of inhibition by tunicamycin. We demonstrate that this difference could be exploited to design MraY-specific inhibitors as potential antibiotics.
N-连接糖基化是真核生物中蛋白质的主要翻译后修饰，其失调是几种人类疾病的病因。酶 UDP-N-乙酰葡萄糖胺：岩藻糖磷酸 N-乙酰葡萄糖胺磷酸转移酶（GlcNAc-1-P-转移酶或 GPT）催化内质网膜中 N-连接糖基化的第一步和关键步骤，是天然产物短杆菌肽的靶标。短杆菌肽具有很强的抗菌活性，抑制细菌细胞壁合成酶 MraY，但由于对人 GPT 的非靶向抑制，其作为抗生素的用途受到限制。我们对短杆菌肽如何抑制 N-连接糖基化的理解以及努力有针对性地靶向 MraY 的努力受到缺乏结构信息的阻碍。在这里，我们展示了与人 GPT 与短杆菌肽复合物的晶体结构。结构和功能分析揭示了 GPT 和 MraY 在短杆菌肽抑制机制方面的差异。我们证明，这种差异可以被利用来设计专门针对 MraY 的抑制剂作为潜在的抗生素。
