Ionophore properties of OmpA of Escherichia coli.
Both porins OmpA1, from wild-strain K12 Escherichia coli, and OmpA2, from a K12 derivative deficient in both OmpF and OmpC, are able to form ion channels in virtually solvent-free membranes. The conductance has been shown to vary in a discrete fashion with different single increment values especially with OmpA2. This behaviour seems to indicate, beside monomers, the presence of aggregates of different sizes. The estimated small pore diameter (0.6-0.7 nm) for the monomeric would explain the weak permeability of this narrow channel toward different solutes. OmpA protein, from experiments of ion selectivity and zero-current potential, is determined weakly anion selective.
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URA 500 CNRS, Faculté des Sciences de Rouen, Mont-Saint Aignan, France.
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Julien
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Orange
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Molle
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D004926:Escherichia coli / Q000737:chemistry*; D007473:Ion Channels / Q000737:chemistry; D007477:Ions; D008051:Lipid Bilayers / Q000737:chemistry; D009943:Organophosphorus Compounds / Q000737:chemistry*
D007473:Ion Channels; D007477:Ions; D008051:Lipid Bilayers; D009943:Organophosphorus Compounds; C008705:octamethyl pyrophosphoramide