Analysis of Aluminum and Divalent Cation Binding to Wheat Root Plasma Membrane Proteins Using Terbium Phosphorescence

Caldwell, Charles R.

doi:10.1104/pp.91.1.233

Cited by 63 publications

(41 citation statements)

References 25 publications

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“…Our present data do not rule out this possibility, and this response is supported by Al-induced organic acid efflux in wheat (Delhaize et al, 1993b). There is evidence to suggest that A1 does not reduce H+-ATPase activity (Kinraide, 1988;Miyasaka et al, 1989), although Al-induced changes in plasma membrane surface properties may indeed affect the function of integral membrane proteins (Caldwell, 1989). We have not tested for the possibility that A1 may have a direct role in depolarizing the E, by virtue of its positive charge crossing the plasma membrane.…”

Section: Lnterpretation Of Dade Responsescontrasting

confidence: 61%

“…Changes in both growth and ion accumulation are consistent with an interaction of A1 with the cell walls and plasma membranes of root cells. A1 has profound effects on membrane structure, altering membrane permeability (Zhao et al, 1987), fluidity (Haug, 1984), protein-lipid interactions (Caldwell, 1989), and surface potential (Haug, 1984;Kinraide et al, 1992). These changes may lead to alterations in membrane function and ion transport (Suhayda and Haug, 1986;Caldwell, 1989;Nicho1 et al, 1993).…”

Section: Physiological Relevancementioning

confidence: 99%

“…A1 has profound effects on membrane structure, altering membrane permeability (Zhao et al, 1987), fluidity (Haug, 1984), protein-lipid interactions (Caldwell, 1989), and surface potential (Haug, 1984;Kinraide et al, 1992). These changes may lead to alterations in membrane function and ion transport (Suhayda and Haug, 1986;Caldwell, 1989;Nicho1 et al, 1993). Much of the recent work with A1 has focused on its effect on Ca2+ fluxes (Huang et al, 1992;Delhaize et al, 1993b;Ryan and Kochian, 1993;, although a causative relationship with A1 toxicity has not been established .…”

Section: Physiological Relevancementioning

confidence: 99%

“…First, Al-induced changes in membrane fluidity may change the conformation and function of transport proteins that are anchored in the membrane matrix (Haug, 1984;Caldwell, 1989). Second, Alinduced changes in the surface potential of the plasma membrane could affect the gating properties of Kt channels (Hille, 1984;Kinraide et al, 1992).…”

Section: Lnterpretation Of Dade Responsesmentioning

confidence: 99%

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Induction of Hexose-Phosphate Translocator Activity in Spinach Chloroplasts

1995

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Many environmental and experimental conditions lead t o accumulation of carbohydrates in photosynthetic tissues. This situation is typically associated with major changes in the mRNA and protein complement of the cell, including metabolic repression of photosynthetic gene expression, which can be induced by feeding carbohydrates directly t o leaves. I n this study we examined the carbohydrate transport properties of chloroplasts isolated from spinach (Spinacia oleracea L.) leaves fed with glucose for severa1 days. lhese chloroplasts contain large quantities of starch, can perform photosynthetic 3-phosphoglycerate reduction, and surprisingly also have the ability t o perform starch synthesis from exogenous glucose-6-phosphate (Clc-6-P) both in the light and in darkness, similarly to heterotrophic plastids. Clucose-1 -phosphate does not act as an exogenous precursor for starch synthesis. Light, ATP, and 3-phosphoglyceric acid stimulate Clc-6-P-dependent starch synthesis. Short-term uptake experiments indicate that a nove1 Clc-6-P-translocator capacity is present in the envelope membrane, exhibiting an apparent K, of 0.54 mM and a V,,, of 2.9 pmol Clc-6-P mg-' chlorophyll h-'. Similar results were obtained with chloroplasts isolated from glucose-fed potato leaves and from water-stressed spinach leaves. l h e generally held view that sugar phosphates transported by chloroplasts are confined to triose phosphates is not supported by these results. A physiological role for a Clc-6-P translocator in green plastids is presented with reference t o the source/ sink function of the leaf.

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Section: Lnterpretation Of Dade Responsescontrasting

confidence: 61%

Section: Physiological Relevancementioning

confidence: 99%

Section: Physiological Relevancementioning

confidence: 99%

Section: Lnterpretation Of Dade Responsesmentioning

confidence: 99%

See 2 more Smart Citations

Induction of Hexose-Phosphate Translocator Activity in Spinach Chloroplasts

1995

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“…Exclusion of AI by root exudates could account for this difference, but it is possible that the more sensitive genotypes have a greater number of Albinding sites at the cell surfaces or that the binding sites have a higher binding affinity. Caldwell (1989) reported that the PM proteins of a more sensitive wheat genotype bound AI more strongly than those of a less sensitive genotype. This greater binding capacity may or may not be associated with a greater negative cell-surface charge density.…”

mentioning

confidence: 99%

Sorption of Aluminum to Plasma Membrane Vesicles Isolated from Roots of Scout 66 and Atlas 66 Cultivars of Wheat

1997

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To further elucidate the mechanisms of differential genotypic tolerance to AI, plasma membrane (PM) vesicles were isolated from whole roots, root tips, and tipless roots of AI3+-sensitive and AI3+-tolerant cultivars (cv) of wheat (Triticum aestivum 1. cv Scout 66 and cv Atlas 66, respectively). Vesicles from cv Scout root tips sorbed more AI than vesicles prepared from any other source. The intrinsic surface-charge density of vesicles isolated from cv Scout was 26% more negative than vesicles from cv Atlas (-37.2 versus -29.5 millicoulombs m-'). Crowth experiments indicated that cv Scout is slightly more sensitive to La3+ than is cv Atlas, that the cultivars are equally sensitive to H+, and that cv Atlas is slightly more sensitive to SeO,' -.l h e difference in sensitivity to AI3+ was very large; for a 50% inhibition, a 16-fold greater activity of AI3+ was required for cv Atlas. Using a newly developed Couy-ChapmanStern model for ion sorption to the P M together with growthresponse curves, we estimate that the difference i n surface-charge density can account for the slightly greater sensitivity of cv Scout to cationic toxicants and the slightly greater sensitivity of cv Atlas to anionic toxicants. According to our estimates the differences in PM surface negativity and AI sorptive capacity probably account for some of the difference in sensitivity to AI3+, but the greater part of the difference probably arises from other tolerance mechanisms expressed in cv Atlas root tips that reduce the amount of AI3+ that can reach the PM.

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