Shift from localized to delocalized protonic energy coupling in thylakoids by permeant amines

Sigalat, Claude; Kouchkovsky, Yaroslav de; Haraux, Francis; Kouchkovsky, Françoise de

doi:10.1016/0005-2728(88)90095-3

Cited by 25 publications

(13 citation statements)

References 38 publications

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“…The achievement of a new stable membrane potential at a lower level could be the result of compensating K+ efflux. In addition, amines are known to interfere with membrane components like polypeptides which are supposed to be involved in proton transport (20). The uptake dependence on external pH supports the proposed model of uniport ofthe charged substrate.…”

Section: Effect Of Extemal Ph On Apparent Kinetic Parameters Of (14c)supporting

confidence: 54%

Uptake of Acidic and Basic Sugar Derivatives in Lemna gibba G1

Sanz¹,

Ullrich²

1989

Plant Physiol.

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The uptake of acidic and basic sugar derivatives in Lemna gibba L. was studied. Uronic acids applied to the experimental solution (50 millimolar) induced a small decrease of the membrane potential (10 ± 1 millivolt galacturonic acid, and 20 ± 4 millivolt glucuronic acid). After incubation of the plants in a 0.1 millimolar solution of these substrates, no decrease in the concentration of reducing groups in the external solution was detected. Respiration increased by 31% with 50 millimolar galacturonic acid, whereas no effect was found with the same concentration of glucuronic acid. Glucosamine caused a considerable concentration-dependent membrane depolarization.(14C)glucosamine uptake followed Michaelis-Menten kinetics together with a linear component. Influx of this substrate was inhibited by glucose but the type of competition could not be clearly distinguished. Glucosamine, 50 millimolar, inhibited the respiration rate by 30%. The glucosamine uptake was pH-dependent, with maximum uptake at around pH 7. Lack of enhancement of uptake by low pH as well as the permanent membrane depolarization suggest a uniport mechanism for the charged species of the substrate and an electroneutral diffusion of the uncharged species.

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Section: Effect Of Extemal Ph On Apparent Kinetic Parameters Of (14c)supporting

confidence: 54%

Uptake of Acidic and Basic Sugar Derivatives in Lemna gibba G1

Sanz¹,

Ullrich²

1989

Plant Physiol.

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“…It is clear that the rate of ATP synthesis is not a unique function of but also depends on the way the proton gradient has been adjusted. We had already reported that a given limited by nigericin addition drives a higher rate of photophosphorylation than the same controlled by light intensity (Sigalat et al, 1985(Sigalat et al, ,1988.…”

Section: Resultsmentioning

confidence: 97%

“…This led to suspicion of artifactual measurements in the case where a localized pattern was found. This question of artifacts was raised in the case of thylakoids (Davenport & McCarty, 1986), but we have suggested that the conflicting results would be better explained by a delocalizing effect of the amines of high pK used to measure but not always added at negligible concentrations (Sigalat et al, 1988).…”

mentioning

confidence: 99%

Flow-force relationships in lettuce thylakoids. 2. Effect of the uncoupler FCCP on local proton resistances at the ATPase level

Sigalat¹,

Kouchkovsky²,

Haraux³

1993

Biochemistry

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The relationship between the steady-state proton gradient (delta pH) and the rate of phosphorylation was investigated in thylakoids under various conditions. Under partial uncoupling by carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP), the rate of ATP synthesis was reduced by less than expected from the decrease of delta pH. This was observed in the case of the pyocyanine-mediated cyclic electron flow around photosystem 1, but not with the H2O-->photosystem 2-->cytochrome b6f-->photosystem 1-->methyl viologen system. In state 4, a unique relation was found between delta pH and the "phosphate potential", delta Gp, regardless of whether the energy level was controlled by light input or FCCP. The anomalous effect of FCCP on the rate of ATP synthesis disappeared when the ATPase was partially blocked by the reversible inhibitor venturicidin, but not in the presence of tentoxin, an irreversible inhibitor. These results are consistent with the existence of a small kinetic barrier for protons, limiting their access to the ATPase. This resistance would be collapsed by FCCP.

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“…The assumption that thylakoids are impermeable to charged Put is an oversimplification. It is known that Cl - channels of the thylakoid membrane open at 30 mV ( Schoenknecht et al, 1988 ) and the influx of Cl - (counter-ions) is expected to neutralize amine molecules and allow its efflux in the stroma ( Sigalat et al, 1988 ). The voltage dependency of those channels may act as a safety valve sensor that hinders Put overaccumulation in the lumen and simultaneously is able to fine tune membrane potential in values sufficient for ATP synthesis ( Ioannidis et al, 2006 ).…”

Section: The Role Of Polyamines In Chemiosmosismentioning

confidence: 99%

Polyamines in chemiosmosis in vivo: A cunning mechanism for the regulation of ATP synthesis during growth and stress

Ioannidis

Kotzabasis

2014

Front. Plant Sci.

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Polyamines (PAs) are low molecular weight amines that occur in every living organism. The three main PAs (putrescine, spermidine, and spermine) are involved in several important biochemical processes covered in recent reviews. As rule of thumb, increase of the cellular titer of PAs in plants is related to cell growth and cell tolerance to abiotic and biotic stress. In the present contribution, we describe recent findings from plant bioenergetics that bring to light a previously unrecognized dynamic behavior of the PA pool. Traditionally, PAs are described by many authors as organic polycations, when in fact they are bases that can be found in a charged or uncharged form. Although uncharged forms represent less than 0.1% of the total pool, we propose that their physiological role could be crucial in chemiosmosis. This process describes the formation of a PA gradient across membranes within seconds and is difficult to be tested in vivo in plants due to the relatively small molecular weight of PAs and the speed of the process. We tested the hypothesis that PAs act as permeable buffers in intact leaves by using recent advances in vivo probing. We found that an increase of PAs increases the electric component (Δψ) and decreases the ΔpH component of the proton motive force. These findings reveal an important modulation of the energy production process and photoprotection of the chloroplast by PAs. We explain in detail the theory behind PA pumping and ion trapping in acidic compartments (such as the lumen in chloroplasts) and how this regulatory process could improve either the photochemical efficiency of the photosynthetic apparatus and increase the synthesis of ATP or fine tune antenna regulation and make the plant more tolerant to stress.

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Shift from localized to delocalized protonic energy coupling in thylakoids by permeant amines

Cited by 25 publications

References 38 publications

Uptake of Acidic and Basic Sugar Derivatives in Lemna gibba G1

Uptake of Acidic and Basic Sugar Derivatives in Lemna gibba G1

Flow-force relationships in lettuce thylakoids. 2. Effect of the uncoupler FCCP on local proton resistances at the ATPase level

Polyamines in chemiosmosis in vivo: A cunning mechanism for the regulation of ATP synthesis during growth and stress

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