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Abstract：
Gram-negative bacteria cause the majority of highly drug-resistant bacterial infections. To cross the outer membrane of the complex Gram-negative cell envelope, antibiotics permeate through porins, trimeric channel proteins that enable the exchange of small polar molecules. Mutations in porins contribute to the development of drug-resistant phenotypes. In this work, we show that a single point mutation in the porin PorB from Neisseria meningitidis, the causative agent of bacterial meningitis, can strongly affect the binding and permeation of beta-lactam antibiotics. Using X-ray crystallography, high-resolution electrophysiology, atomistic biomolecular simulation, and liposome swelling experiments, we demonstrate differences in drug binding affinity, ion selectivity and drug permeability of PorB. Our work further reveals distinct interactions between the transversal electric field in the porin eyelet and the zwitterionic drugs, which manifest themselves under applied electric fields in electrophysiology and are altered by the mutation. These observations may apply more broadly to drug-porin interactions in other channels. Our results improve the molecular understanding of porin-based drug-resistance in Gram-negative bacteria.
摘要：
革兰氏阴性菌引起大多数高度耐药的细菌感染。穿过复杂的革兰氏阴性细胞包膜的外膜，抗生素渗透通过孔，能够交换小极性分子的三聚体通道蛋白。孔蛋白中的突变有助于耐药表型的发展。在这项工作中,我们显示了来自脑膜炎奈瑟菌的孔蛋白PorB的单点突变，细菌性脑膜炎的病原体，会强烈影响β-内酰胺抗生素的结合和渗透。用X射线晶体学,高分辨率电生理学，原子生物分子模拟，和脂质体溶胀实验，我们证明了药物结合亲和力的差异，PorB的离子选择性和药物渗透性。我们的工作进一步揭示了孔眼横向电场与两性离子药物之间的独特相互作用，在电生理学中施加的电场下表现出来，并因突变而改变。这些观察结果可能更广泛地适用于其他通道中的药物-孔蛋白相互作用。我们的结果提高了对革兰氏阴性菌中基于孔蛋白的耐药性的分子理解。
