The Properties of the Galactose-Binding Protein, the Possible Chemoreceptor for Galactose Chemotaxis in Escherichia coli

Boos, Winfried

doi:10.1159/000395423

Cited by 8 publications

(1 citation statement)

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“…A real change in membrane potential stimulated by galactose would mean the involvement of ion current(s) in the chemotaxis process to galactose. A change in the surface charge of the membrane, caused by the same stimulus, would indicate either vertical displacement of one or more membrane proteins (Borochov and Shinitzky, 1976) or conformational changes of these proteins (Boos, 1974;Eisenbach and Caplan, 1979;Kell, 1979) ocurring, e.g., as a consequence of the binding of the attractant/binding-protein complex to the cytoplasmic membrane (Wang and Koshland, 1980).…”

Section: Introductionmentioning

confidence: 99%

Distinction between changes in membrane potential and surface charge upon chemotactic stimulation of Escherichia coli

Eisenbach¹,

Margolin²,

Ciobotariu³

et al. 1984

Biophysical Journal

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Galactose and other chemotactic attractants have been shown to trigger an apparent hyperpolarization in Escherichia coli (Eisenbach, M., 1982, Biochemistry, 21:6818-6825). The probe used to measure membrane potential in that study, tetraphenylphosphonium (TPP+), may respond also to surface-charge changes in the membrane. The distinction between true changes in membrane potential and changes in the surface charge of the membrane is crucial for the study of this phenomenon in bacterial chemotaxis. To distinguish between these parameters, we compared the response to galactose with different techniques: K+ distribution in the presence of valinomycin (measured with a K+-selective electrode), TPP+ distribution (measured with a TPP+-selective electrode) at different ionic strengths, absorbance changes of bis(3-phenyl-5-oxoisoxazol-4-yl)pentamethineoxonol (oxonol V), and fluorescence changes of three probes with different mechanisms of response. All the techniques revealed stimulation by galactose of transient hyperpolarization, of comparable magnitude. This indicates the involvement of ion currents rather than alterations of local surface properties.

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