Letellier L, Locher K P, Plançon L, Rosenbusch J P
Biozentrum, University of Basel, CH-4056 Basel, Switzerland.
J Biol Chem. 1997 Jan 17;272(3):1448-51. doi: 10.1074/jbc.272.3.1448.
An in vitro assay of iron-ferrichrome translocation across the FhuA protein of outer membranes from Escherichia coli has been devised. Upon reconstitution into large lipid vesicles, bacteriophage T5 binds to this polyvalent receptor, triggering a conformational change that resulted in channel opening. This facilitates the translocation of an iron(III)-siderophore, without the complexities involved in the in vivo process. Efflux of 55Fe(III)-ferrichrome across FhuA channels was determined quantitatively by monitoring the release of trapped radioactivity. The assay is rapid, reliable, and specific, because other bacteriophages, such as Phi80, fail to trigger channel opening of the FhuA receptor.
已经设计了一种体外测定铁-铁载体穿过大肠杆菌外膜FhuA蛋白转运的方法。当重组到大型脂质囊泡中时，噬菌体T5与这种多价受体结合，引发构象变化，导致通道打开。这促进了铁（III）-铁载体的转运，而没有体内过程中涉及的复杂性。通过监测捕获的放射性物质的释放，定量测定了55Fe（III）-铁载体通过FhuA通道的流出。该测定方法快速、可靠且具有特异性，因为其他噬菌体，如Phi80，无法触发FhuA受体的通道打开。
