Ligand-specific opening of a gated-porin channel in the outer membrane of living bacteria
Ligand-specific opening of a gated-porin channel in the outer membrane of living bacteria
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DOI：
10.1126/science.276.5316.1261
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发表时间：
1997-05-23
期刊：
影响因子：
56.9
通讯作者：
Klebba, PE
中科院分区：
文献类型：
--
作者：
Jiang, XQ;Payne, MA;Klebba, PE
配体门控膜通道选择性地促进铁进入原核细胞。铁在新陈代谢中的重要作用使其成为细菌致病的决定因素和治疗策略的目标。在革兰氏阴性细菌中，依赖于TonB的外膜蛋白形成充满能量的门控小孔，结合铁螯合物(铁载体)并将其内化。通过监测氮氧化物共价结合的自旋标记物的迁移率，用电子自旋共振光谱观察了大肠杆菌铁肠杆菌素受体FepA在体内的时间分辨操作。FepA的配体结合表面环通常关闭其跨膜通道，在铁和毒素(结肠素)运输过程中表现出能量依赖的结构变化。这些变化不仅与配体结合有关，而且发生在通过外膜双层摄取配体的过程中。结果表明，在体内，门控孔蛋白通道在膜转运过程中是开放和关闭的。
Ligand-gated membrane channels selectively facilitate the entry of iron into prokaryotic cells. The essential role of iron in metabolism makes its acquisition a determinant of bacterial pathogenesis and a target for therapeutic strategies. In Gram-negative bacteria, TonB-dependent outer membrane proteins form energized, gated pores that bind iron chelates (siderophores) and internalize them. The time-resolved operation of the Escherichia coli ferric enterobactin receptor FepA was observed in vivo with electron spin resonance spectroscopy by monitoring the mobility of covalently bound nitroxide spin labels. A ligand-binding surface loop of FepA, which normally closes its transmembrane channel, exhibited energy-dependent structural changes during iron and toxin (colicin) transport. These changes were not merely associated with ligand binding, but occurred during ligand uptake through the outer membrane bilayer. The results demonstrate by a physical method that gated-porin channels open and close during membrane transport in vivo.