Open AccessIn vivo and in vitro Studies of the Inhibition of the Channel Activity of Colicins by Gadolinium
Author(s) -
Bonhivers Mélanie,
Guihard Gilles,
Pattus Franc,
Letellier Lucienne
Publication year - 1995
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1995.0155l.x
Subject(s) - colicin , gadolinium , in vivo , in vitro , chemistry , channel (broadcasting) , pharmacology , biophysics , medicine , biology , biochemistry , computer science , escherichia coli , microbiology and biotechnology , computer network , organic chemistry , gene
The primary effects of the ionophoric colicins A, E1 nd B on Escherichia coli cells include triggering an efflux of cytoplasmic potassium, and a decrease of internal ATP as consequences of the opening of ionic channels in the cytoplasmic membrane. We report that micromolar concentrations of gadolinium and other members of the lanthanide family inhibited the efflux of potassium and the ATP decrease and that the cells recovered both ATP and potassium within a few minutes. Gadolinium, in the same concentration range also efficiently inhibited the channel activity of colicins A, E1, B and of the isolated channel‐forming domain of colicin A in planar lipid bilayers. Colicin N was much less sensitive to the trivalent ion in planar lipid bilayers, consistent with the lack of effect of gadolinium on this colicin in vivo. Our data suggest that lanthanide ions act by direct binding to the colicin molecule and that this binding affects both its single‐channel conductance and gating behaviour.