The protonmotive force in Staphylococcus aureus

Abstract

We have demonstrated the release from respiratory control in membrane particles from Micrococcus denitrificans by carbonyl cyanide m-chlorophenylhydrazone and combinations of gramicidin, valinomycin, nigericin, monensin and dianemycin (John & Hamilton, 1970, 1972. From these findings it has been concluded that the increases in membrane permeability show ion specificity identical with that demonstrated in other systems (Henderson et al., 1969). Tetrachlorosalicylanilide and trichlorocarbanilide have also been found to be proton-translocating uncouplers. Studies of protoplast and spheroplast stability in hyperosmotic media (Hamilton, 1970) and the decay of an acid pulse (W. A. Hamilton, unpublished work) have allowed us -to extend these findings to the organisms Bacillus megaterium, Micrococcus lysodeikticus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa.The behaviour of trichlorocarbanilide is somewhat anomalous, in as much as it apparently increases both HI and Cl-permeability. Accordingly this compound has been further studied with black lipid membranes formed from oxidizedcholesterol or phosphatidylcholine (lecithin) +cholesterol.In KCI media, trichlorocarbanilide caused a timedependent increase in membrane conductance. This effect was decreased by the replacement of chloride by sulphate or acetate, but was unaffected by the replacement of KCI by NaCl. In the presence of trichlorocarbanilide, anionic diffusion potentials were observed across these membranes in concentration gradients of NaCl or K2SO4. This confirms the increase in anion permeability, since untreated membranes demonstrated cation diffusion potentials under these conditions. Where, however, the concentration gradient across the membrane was in the form of a pH gradient in an acetate-buffered medium with a low (10mM) chloride concentration, the diffusion potential measured in the presence of trichlorocarbanilide was acid-sidenegative. This implies an enhanced proton permeability of the same order as that for chloride. In these artificial membrane systems, therefore, we have been able to verify the action of trichlorocarbanilide in increasing the permeability to protons and to anions, in particular to those of small hydrated radius, such as chloride. We have found no evidence for significant effects with the alkali-metal cations.

Conservation and transformation of energy by bacterial membranes.

“…Parallel observations are beginning to appear from studies on M. phlei (14,157) and on Staphylococcus (180,286). Skulachev (350) refers to experiments which show that respiring vesicles of M. lysodeikticus accumulate lipidsoluble anions, indicating again the generation of a positive potential.…”

Mechanisms of Energy Coupling to the Transport of Amino Acids by Staphylococcus aureus

“…UTe have already demonstrated the generation of a protonmotive force in this organism [5]. We have also shown the accumulation of the basic lysine in response to a diffusion potential [i], and that of the neutral glycine and isoleucine in response to a transient protonmotive force resulting from valinomycininduced potassium efflux [2].…”

Energetic basis of cadmium toxicity in Staphylococcus aureus

“…ATP was assayed with firefly lantern extract (FLE-50) as described by Maloney & Wilson (1975). The intra-cellular concentration of ATP was calculated using a value of 1.55 ld cell water mg i dry weight, according to Jeacocke et al (1972).…”

“…The magnitude of Aft was calculated from the Nernst equation: A~b = 61.7 Rb~./Rboo,, using the steady-state concentration values (Kashket 1985). Concentration gradients were estimated on the basis of the intracellular water content according to Jeacocke et al (1972).…”