Modeling ligand-gated receptor activity. FhuA-mediated ferrichrome efflux from lipid vesicles triggered by phage T5

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 openin...

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Bibliographic Details
Published inThe Journal of biological chemistry Vol. 272; no. 3; pp. 1448 - 1451
Main Authors Letellier, L, Locher, K P, Plançon, L, Rosenbusch, J P
Format Journal Article
LanguageEnglish
Published United States 17.01.1997
Subjects
Bacterial Outer Membrane Proteins - metabolism
Bacteriophages - metabolism
Biological Transport
Escherichia coli
Escherichia coli Proteins
Ferrichrome - metabolism
Ligands
Lipid Metabolism
phage T5
Receptors, Virus - metabolism
Spectrometry, Fluorescence
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Summary: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.
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ISSN:0021-9258
DOI:10.1074/jbc.272.3.1448