The driving force for proton(s) metabolites cotransport in bacterial cells

Rottenberg, Hagai

doi:10.1016/0014-5793(76)80493-0

Cited by 102 publications

(39 citation statements)

References 11 publications

(17 reference statements)

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“…However, the ApH appears to be large only when the external pH is comparatively low and decreases to very low values at neutral external pH, whereas A~ is constant over the pH range 5 -9 (Padan et al, 1976;Ramos et al, 1976). This could make it favourable and perhaps inevitable for an organism to use the membrane potential as the main driving force at pH values of 7.5 and higher (Rottenberg, 1976). This can only be attained when the carrier-substrate complex is positively charged which means, in the case of oxalate, cotransport of at least three protons.…”

Section: Discussionmentioning

confidence: 99%

Active transport of oxalate by Pseudomonas oxalaticus OX1

et al. 1977

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Abstract. Membrane vesicles isolated from oxalategrown cells of Pseudomonas oxalaticus accumulated oxalate by an inducible transport system in unmodified form against a concentration gradient. This accumulation was dependent on the presence of a suitable electron donor system such as ascorbate-phenazinemethosulphate. In the presence of this energy source, steady state levels of accumulation of oxalate were 10-20-fold higher than in its absence. The oxalate transport system involved showed a high affinity for oxalate (Kin = 11 laM) and was highly specific. Oxalate transport was not affected by the presence of other dicarboxylic acids, such as malate, succinate and fumarate and only partly inhibited by acetate. The energy requirement for oxalate transport is discussed and it is concluded that this requirement is most likely equivalent to i mole of ATP per mole of oxalate.

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Section: Discussionmentioning

confidence: 99%

Active transport of oxalate by Pseudomonas oxalaticus OX1

et al. 1977

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“…The driving force for the overall process is equal to the electrochemical gradient for the co-transported ion (AgH+) plus that for the cotransported substrate (A#s) (32). For If transport occurs by the system outlined above, several criteria should be fulfilled: first, the uptake velocity should show carriermediated kinetic behavior with respect to substrate and proton concentrations; second, transport should be sensitive to those agents interfering with the generation and maintenance of the proton electrochemical gradient; third, transport should be affected by reagents interfering with the membrane-bound carrier protein.…”

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confidence: 99%

Electrogenic Sucrose Transport in Developing Soybean Cotyledons

Lichtner

Spanswick²

1981

Plant Physiol.

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Addition of sucrose to a solution bathing an excised developing soybean cotyledon causes a transient depolarization of the membrane potential, as measured using standard electrophysiological techniques. The magnitude of the depolarization is dependent on the concentration of both sucrose and protons in a manner which suggests carrier mediation; this process has an apparent Km for sucrose of about 10 milimolar. Agents interfering with the generation or maintenance of a proton electrochemical gradient eliminate these depolarizations. Electrogenic sugar transport is sensitive to sulfhydryl-modifying reagents; their effect appears to be through a direct interaction with the carrier protein and/or with the process establishing the proton electrochemical gradient across the plasma membrane. p-Chloromercuribenzene sulfonate appears to be a selective inhibitor of the carrier-mediated process itself.and protons inside and outside the cell, respectively, and A4A is the membrane potential.In physical terms, transport across the cell membrane is facilitated by a carrier which alternately exposes its binding sites for proton(s) and solute on the external and internal side of the membrane (Fig. 1). The movement of protons into the cell upon addition of substrate causes a transient change in the voltage difference across the plasma membrane (8, 10, 22, 26, 29; see 22 for additional references); the value towards which the membrane potential moves is Ecotra. (16), the voltage at which no net current flows through the co-transport system. It can be derived from equation (1) (2) The concept that the energy stored in an existing ion gradient can be used to accomplish the accumulation of organic solutes is based on the early ideas of Crane and Mitchell, now commonly regarded as an outgrowth of the chemiosmotic theory. A history of the development of these ideas has been presented by Crane (4). In this scheme, the movement of an ion down its electrochemical gradient provides energy for the coupled uptake of another solute; the process is termed co-transport or symport. If transport occurs by the system outlined above, several criteria should be fulfilled: first, the uptake velocity should show carriermediated kinetic behavior with respect to substrate and proton concentrations; second, transport should be sensitive to those agents interfering with the generation and maintenance of the proton electrochemical gradient; third, transport should be affected by reagents interfering with the membrane-bound carrier protein.Developing soybean seeds offer an excellent experimental system for investigating transport processes. Since there are no symplasmic connections between parent plant and embryo (37), assim- LICHTNER AND SPANSWICK ilate must negotiate at least one plasma membrane between the site of phloem unloading and that of storage. Photosynthate, 90 to 95% in the form of sucrose (39), reaches the seeds by the ventral phloem bundles traversing the carpel (pod) and anastomosing through the outer integument. Phloem translocate...

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“…DISCUSSION A variable stoichiometry appears to be an intrinsic attribute of phosphate-linked exchanges in S. lactis, and this unusual finding is relevant to several areas of study. That stoichiometry might change with pH in bacterial systems has been suggested before (5)(6)(7) but always on the basis of comparisons of driving forces or of their kinetic effects and not from measurement of the respective net fluxes. In this regard, then, the data collected here provide a clear and direct test to reinforce the general finding.…”

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Variable stoichiometry of phosphate-linked anion exchange in Streptococcus lactis: implications for the mechanism of sugar phosphate transport by bacteria.

Ambudkar¹,

Sonna²,

Maloney³

1986

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

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Phosphate/2-deoxyglucose 6-phosphate antiport in Streptococcus lactis showed an exchange stoichiometry that varied over a 2-fold range when assay pH was shifted between pH 8.2 and pH 5.2. At pH 7.0 and above, 2 mol of phosphate moved per mol of sugar phosphate; at pH 6.1 the ratio was 1.5:1, while at pH 5.2 the overall stoichiometry fell to 1. (Fig. LA) represented about a 100-fold accumulation of substrate above its original medium concentration. The vesicles, loaded with sugar phosphate, were then reisolated by centrifugation, resuspended, and redistributed into three tubes, having assay buffer at pH 7.0, pH 6.1, or pH 5.2.Abbreviation: Mops, 3-(N-morpholino)propanesulfonic acid. 280The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

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The driving force for proton(s) metabolites cotransport in bacterial cells

Cited by 102 publications

References 11 publications

Active transport of oxalate by Pseudomonas oxalaticus OX1

Active transport of oxalate by Pseudomonas oxalaticus OX1

Electrogenic Sucrose Transport in Developing Soybean Cotyledons

Variable stoichiometry of phosphate-linked anion exchange in Streptococcus lactis: implications for the mechanism of sugar phosphate transport by bacteria.

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