Chang Nienping, Kim Hoyoung, Kim Uijin, Cho Yongju, Yoo Youngki, Lee Hyunsook, Kim Ji Won, Kim Min Sung, Lee Jaeho, Cho Young-Lag, Kim Kitae, Yong Dongeun, Cho Hyun-Soo
Department of Systems Biology and Division of Life Sciences, Yonsei University, 50 Yonsei-ro, Seoul, Republic of Korea.
Vollum Institute, Oregon Health & Science University, 3232 SW Research Dr, Portland, OR, USA.
Nat Commun. 2025 Jul 1;16(1):5744. doi: 10.1038/s41467-025-61169-3.
Anhydromuropeptide permease (AmpG) is a transporter protein located in the inner membrane of certain gram -negative bacteria, involved in peptidoglycan (PG) recycling and β-lactamase induction. Decreased AmpG function reduces resistance of antibiotic-resistant bacteria to β-lactam antibiotics. Therefore, AmpG-targeting inhibitors are promising 'antibiotic adjuvants'. However, as the tertiary structure of AmpG has not yet been identified, the development of targeted inhibitors remains challenging. We present four cryo-electron microscopy (cryo-EM) structures: the apo-inward and apo-outward state structures and the inward-occluded and outward states complexed with the substrate GlcNAc-1,6-anhMurNAc. Through functional analysis and molecular dynamics (MD) simulations, we identified motif A, which stabilizes the outward state, substrate-binding pocket, and protonation-related residues. Based on the structure of AmpG and our experimental results, we propose a muropeptide transport mechanism for AmpG. A deeper understanding of its structure and transport mechanism provides a foundation for the development of antibiotic adjuvants.
无水肽聚糖通透酶（AmpG）是一种位于某些革兰氏阴性菌内膜的转运蛋白，参与肽聚糖（PG）的循环利用和β-内酰胺酶的诱导。AmpG功能的降低会降低耐药菌对β-内酰胺类抗生素的耐药性。因此，靶向AmpG的抑制剂有望成为“抗生素佐剂”。然而，由于AmpG的三级结构尚未确定，靶向抑制剂的开发仍然具有挑战性。我们展示了四种冷冻电子显微镜（cryo-EM）结构：无底物内向和外向状态结构以及与底物GlcNAc-1,6-anhMurNAc复合的内向封闭和外向状态结构。通过功能分析和分子动力学（MD）模拟，我们确定了稳定外向状态的基序A、底物结合口袋和与质子化相关的残基。基于AmpG的结构和我们的实验结果，我们提出了一种AmpG的肽聚糖转运机制。对其结构和转运机制的更深入理解为抗生素佐剂的开发提供了基础。
