The membrane potential as the driving force for the accumulation of lysine by <i>Staphylococcus aureus</i>

Niven, Donald F.; Jeacocke, Robin E.; Hamilton, W. Allan

doi:10.1016/0014-5793(73)80030-4

Cited by 34 publications

(18 citation statements)

References 3 publications

(2 reference statements)

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“…Work with intact cells (28)(29)(30)(31)(32) leads to the same conclusion and has begun to provide evidence for symport of protons with these substrates. The results still fall short of proving that Mitchell's proton-motive force is both necessary and sufficient for energy coupling of active transport, but it seems to us that this is the most rational and the most economical interpretation presently available.…”

Section: Discussionmentioning

confidence: 79%

Role of an Electrical Potential in the Coupling of Metabolic Energy to Active Transport by Membrane Vesicles of Escherichia coli

Hirata

Altendorf

Harold

1973

Proc. Natl. Acad. Sci. U.S.A.

172

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Membrane vesicles from E. coli can oxidize D-lactate and other substrates and couple respiration to the active transport of sugars and amino acidl8. The present experiments bear on the nature of the link between respiration and transport.Respiring vesicles were found to accumulate dibenzyldimethylammonium ion, a synthetic lipid-soluble cation that serves as an indicator of an electrical potential. Escherichia coti, like other bacteria, accumulates nutrients from the medium by virtue of specific transport systems ("permeases"). Many nutrients, including amino acids, ,-galactosides, and certain inorganic ions, are transported in the face of large concentration gradients without any apparent chemical modification. Such "active transport" requires the performance of work and implies the coupling of transport systems to the major metabolic pathways of the cell (1-4).A partially resolved system, in which the mechanism of energy coupling may be more amenable to analysis than it is in the intact cell, became available through the work of H. R. Kaback and his associates. In a remarkable research program (5), these investigators demonstrated that isolated membrane vesicles of E. coti and other bacteria can couple active transport of many sugars, amino acids, and certain ions to the oxidation of particular respiratory substrates such as Dlactate. Since these vesicles neither make ATP by oxidative phosphorylation nor utilize exogenous ATP as an energy donor for transport, the coupling of oxidation to transport Abbreviations: DDA+, dibenzyldimethylammonium ion; TPB-, tetraphenylboron; TCS, tetrachlorosalicylanilide; CCCP, carbonylcyanide m-chlorophenylhydrazone; HOQNO, 2-heptyl-4 hydroxyquinoline-N-oxide. * To whom requests for reprints should be addressed, at National Jewish Hospital and Research Center. 1804probably occurs quite directly at the level of the membrane and its constituent proteins (5-7). Kaback and Barnes (8) proposed a tentative mechanism by which the coupling might be effected: the transport carriers are thought to monitor the redox state of the electron-transport chain and themselves undergo cyclic oxidation and reduction of critical sulfhydryl groups; each cycle is accompanied by concurrent changes in the orientation of the carrier center and in its affinity for the substrate, leading to accumulation of the substrate in the lumen of the vesicle. Serious shortcomings of this hypothesis have been pointed out by several investigators (1, 9-11).An alternative mechanism for the coupling of respiration to transport can be envisaged in terms of Mitchell's chemiosmotic hypothesis (12, 13). Briefly, he postulates that the respiratory chain translocates protons outward, thereby generating across the membrane an electrical potential (interior negative) and, under certain conditions, a pH gradient as well (interior alkaline). These gradients, which together constitute a force tending to pull protons back into the vesicle, are held to effect active transport by virtue of carriers that translocate simultaneousl...

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Section: Discussionmentioning

confidence: 79%

Role of an Electrical Potential in the Coupling of Metabolic Energy to Active Transport by Membrane Vesicles of Escherichia coli

Hirata

Altendorf

Harold

1973

Proc. Natl. Acad. Sci. U.S.A.

172

View full text Add to dashboard Cite

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“…aureus, considerable evidence has been presented in favour of this latter suggestion [6]. In this present investigation, we have extended these studies and examined the effect of valinomycininduced potassium efflux on the uptake not only of basic, but also of neutral and acidic amino acids.…”

Section: Discussionmentioning

confidence: 80%

“…lc) lysine accumulation was found to occur in response to the membrane potential [6]. The addition of valinomycin at 10 min ( fig.…”

Section: Discussionmentioning

confidence: 89%

“…aureus was grown and harvested as described previously [6]. Cells from a 100 ml culture were washed once in 33 mM potassium phosphate buffer, pH 7.0, containing 10 mM MgSO 4 (70 ml) and resuspended in that buffer system (50 ml).…”

Section: Preparation Of Cell Suspensionmentioning

confidence: 99%

“…These results are in keeping with the driving forces suggested previously for amino acid accumulation by Staph. aureus [6], the basic, acidic and neutral amino acids behaving as cationic, anionic and neutral substrates respectively, and responding to the membrane potential, pH gradient and total protonmotive force.…”

Section: Introductionmentioning

confidence: 99%

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