Membrane potential change as pH changes from 7 to 5

Range pH 7 134±17mV: pH 5 85±13 mV mV
Organism Bacteria Escherichia coli
Reference Lo CJ, Leake MC, Pilizota T, Berry RM. Nonequivalence of membrane voltage and ion-gradient as driving forces for the bacterial flagellar motor at low load. Biophys J. 2007 Jul 1 93(1):294-302. p.297 left column bottom paragraphPubMed ID17416615
Method Abstract: "Many bacterial species swim using flagella. The flagellar motor couples ion flow across the cytoplasmic membrane to rotation. Ion flow is driven by both a membrane potential (V(m)) and a transmembrane concentration gradient. To investigate their relation to bacterial flagellar motor function [investigators] developed a fluorescence technique to measure V(m) in single cells, using the dye tetramethyl rhodamine methyl ester. [They] used a convolution model to determine the relationship between fluorescence intensity in images of cells and intracellular dye concentration, and calculated V(m) using the ratio of intracellular/extracellular dye concentration."
Comments P.297 left column bottom paragraph: "Fig. 3 A shows the dependence of Vm on pHex for E. coli cells expressing ...proton-driven wild-type flagellar motors. Vm pH changes from 7 to 5... from 134±17 to 85±13 mV with wildtype motors."
Entered by Uri M
ID 109775