Gadolinium ion inhibits loss of metabolites induced by osmotic shock and large stretch-activated channels in bacteria.
Bacteria subjected to a hypotonic osmotic shock lose internal ions and also metabolites, without lysis of the cells. We show that the presence in the shock medium, at submillimolar concentrations, of the ion gadolinium, recently shown to block stretch-activated channels in Xenopus oocytes [Yang, X.-C. & Sachs, F. (1989) Science 243, 1068-1071], was sufficient to inhibit shock-induced release of metabolites such as lactose and ATP in Escherichia coli and ATP in Streptococcus faecalis. Moreover, gadolinium was observed, in patch-clamp experiments, to inhibit the giant stretch-activated channels of E. coli, S. faecalis. and Bacillus subtilis. Taken together, these data suggest that stretch-activated channels are localized in the cytoplasmic membrane of Gram-negative and Gram-positive bacteria, where they control the efflux of osmotic solutes, thus probably playing a major role in the response to hypotonic osmotic shock.
Berrier
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C
Laboratoire des Biomembranes, Unité de Recherche Associée au Centre National de la Recherche Scientifique 1116, Université Paris-Sud, Orsay, France.
Coulombe
A
A
Szabo
I
I
Zoratti
M
M
Ghazi
A
A
D000255:Adenosine Triphosphate / Q000378:metabolism; D001412:Bacillus subtilis / Q000187:drug effects* / Q000378:metabolism; D002412:Cations; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism; D005682:Gadolinium / Q000494:pharmacology*; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D007785:Lactose / Q000378:metabolism; D008564:Membrane Potentials; D009995:Osmosis; D011188:Potassium / Q000378:metabolism; D012413:Rubidium / Q000378:metabolism
D002412:Cations; D005971:Glutamates; D018698:Glutamic Acid; D000255:Adenosine Triphosphate; D005682:Gadolinium; D007785:Lactose; D012413:Rubidium; D011188:Potassium