The effect of bacterial signal indole on the electrical properties of lipid membranes

Abstract

Indole is an important biological signalling molecule produced by many Gram positive and Gram negative bacterial species, including Escherichia coli. Here we study the effect of indole on the electrical properties of lipid membranes. Using electrophysiology, we show that two indole molecules act cooperatively to transport charge across the hydrophobic core of the lipid membrane. To enhance charge transport, induced by indole across the lipid membrane, we use an indole derivative, 4 fluoro-indole. We demonstrate parallels between charge transport through artificial lipid membranes and the function of complex eukaryotic membrane systems by showing that physiological indole concentrations increase the rate of mitochondrial oxygen consumption. Our data provide a biophysical explanation for how indole may link the metabolism of bacterial and eukaryotic cells. Control system: The bacterial signal indole and its derivative 4 fluoro-indole are shown to increase the conductance of ions through lipid membranes (see picture). In addition, it is reported that these molecules can affect the oxygen consumption in mitochondria by providing an electric shunt across the lipid membrane. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.