Cu2+ Reduction by Tomato Root Plasma Membrane Vesicles

Holden, Marcia J.; Crimmins, T. J.; Chaney, Rufus L.

doi:10.1104/pp.108.3.1093

Cited by 17 publications

(19 citation statements)

References 16 publications

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“…Experiments using both higher plants (e.g. Norvell et al 1993;Welch et al 1993, Holden et al 1995 and the yeast Saccharomyces cerevisiae (Hassett and Kosman 1995) have also provided evidence that Fe-limitation results in enhanced FC-R and cupric reductase activities, leading to the suggestions that the same reductase is responsible for both activities. Furthermore, both Fe-limitation and Cu-limitation result in increased FC-R activity by pea roots (Cohen et al 1997).…”

Section: Resultsmentioning

confidence: 93%

“…Evidence in favor of reduction of cupric complexes has been presented for Thalassiosira weis¯ogii (Jones et al 1987), and reduction of cupric complexes has often been tacitly assumed in higher-plant experiments (by analogy with the reduction of ferric complexes). Conversely, Holden et al (1995) provided evidence that cupric reduction by root plasma membrane vesicles isolated from iron-limited tomato plants was a function of the free [Cu 2+ ], rather than the concentration of Cu(II)-chelate. Using a similar approach with Fe-limited C. reinhardtii cells, it may be shown that the rate of reduction of 250 lM Cu(II)-chelate is also a function of the [Cu 2+ ] (Fig.…”

Section: Resultsmentioning

confidence: 95%

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Ferric and cupric reductase activities in the green alga Chlamydomonas reinhardtii : experiments using iron-limited chemostats

Weger

1999

Planta

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Cells of the green alga Chlamydomonas reinhardtii Dangeard were grown in Fe-limited chemostat culture over a range of growth rates (0.15±1.5 d A1 ). Greater cell densities and culture chlorophyll levels were achieved using an excess of chelator [ethylenediamine di-(o-hydroxyphenylacetic acid)] relative to FeCl 3 (80:1), compared to growth using a 1:1 chelator:FeCl 3 ratio. The C. reinhardtii cells reduced extracellular ferric chelates, and ferric chelate reductase activity increased with increasing Fe-limited growth rates. However Fesucient cells exhibited a low rate of ferric chelate reductase activity, similar to severely Fe-limited cells. Iron-limited cells were capable of reducing a wide variety of ferric chelates, representing a wide range of stability constants, at similar rates, suggesting that the stability constants of ferric complexes are not important determinants of ferric reducing activity. Cupric reductase activity also increased with increasing Fe-limited growth rates, and Cu(II) was preferentially reduced compared to Fe(III). These results suggest that both reductase activities may represent the same plasmamembrane enzyme. The rate of cupric reduction was a function of the free [Cu 2+ ], not the total [Cu(II)], suggesting that free Cu 2+ is the actual substrate for cupric reductase activity.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 95%

Ferric and cupric reductase activities in the green alga Chlamydomonas reinhardtii : experiments using iron-limited chemostats

Weger

1999

Planta

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“…Welch et al, 1993;Holden et al, 1995), it w a s not clear whether these activities are relevant to copper uptake. By studying copper uptake a n d cupric reductase i n a n organism with a well-characterized response to copper deficiency, it h a s been possible for us to correlate copperresponsive changes in cupric reductase activity with other changes that occur in response to copper supply, and to make a case for cupric reductase to be a general component of a copper-uptake pathway.…”

Section: Cupric Reductasementioning

confidence: 99%

Regulated Copper Uptake in Chlamydomonas reinhardtii in Response to Copper Availability

et al. 1996

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A saturable and temperature-dependent copper uptake pathway has been identified in Chlamydomonas reinhardtii. The uptake system has a high affinity for copper ions (Km approximately 0.2 [mu]M) and is more active in cells that are adapted to copper deficiency than to cells grown in a medium containing physiological (submicromolar to micromolar) copper ion concentrations. The maximum velocity of copper uptake by copper-deficient cells (169 pmol h-1 106 cells-1 or 62 ng min-1 mg-1 chlorophyll) is up to 20-fold greater than that of fully copper-supplemented cells, and the Km (approximately 2 x 102 nM) is unaffected. Thus, the same uptake system appears to operate in both copper-replete and copper-deficient cells, but its expression or activity must be induced under copper-deficient conditions. A cupric reductase activity is also increased in copper-deficient compared with copper-sufficient cells. The physiological characteristics of the regulation of this cupric reductase are compatible with its involvement in the uptake path-way. Despite the operation of the uptake pathway under both copper-replete and copper-deficient conditions, C. reinhardtii cells maintained in fully copper-supplemented cells do not accumulate copper in excess of their metabolic need. These results provide evidence for a homeostatic mechanism for copper metabolism in C. reinhardtii.

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“…Wild-type pea seedlings suffering from Fe deficiency increase ferric-chelate reductase activity in roots and accumulate a range of cations in leaves . Coincident with increased ferric-chelate reductase activity in pea roots, the ability of roots to reduce Cu(I1) and Mn(II1) also increases , with recent evidence indicating that the same enzyme of tomato (Lycopersicon esculentum) roots is responsible for both the reduction of ferric chelates and Cu(I1) (Holden et al, 1995). Furthermore, Holden et al (1995) suggested that the reduction of Cu(I1) by tomato roots has little or no physiological relevance in plants growing in soil.…”

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confidence: 99%

“…Coincident with increased ferric-chelate reductase activity in pea roots, the ability of roots to reduce Cu(I1) and Mn(II1) also increases , with recent evidence indicating that the same enzyme of tomato (Lycopersicon esculentum) roots is responsible for both the reduction of ferric chelates and Cu(I1) (Holden et al, 1995). Furthermore, Holden et al (1995) suggested that the reduction of Cu(I1) by tomato roots has little or no physiological relevance in plants growing in soil. Welch et al (1993) speculated that ferricchelate reductase has a general role in regulating cation uptake by plant roots.…”

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confidence: 99%

A Metal-Accumulator Mutant of Arabidopsis thaliana

Delhaize

1996

Plant Physiology

118

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A mutation designated manl (for =ganese accumulator) was found to cause Arabidopsis fhaliana seedlings to accumulate a range of metals. The manl mutation segregated as a single recessive locus located on chromosome 3. When grown on soil, mutant seedlings accumulated M n (7.5 times greater than wild type), Cu (4.6 times greater than wild type), Zn (2.8 times greater than wild type), and Mg (1.8 times greater than wild type) in leaves. In addition to these metals, the manl mutant accumulated 2.7-fold more S in leaves, primarily in the oxidized form, than wild-type seedlings. Analysis of seedlings grown by hydroponic culture showed a similar accumulation of metals in leaves of manl mutants. Roots of manl mutants also accumulated metals, but unlike leaves they accumulated 10-fold more total Fe (symplasmic and apoplasmic combined) than wild-type roots. Roots of manl mutants possessed greater (from 1.8-to 20-fold) ferric-chelate reductase activity than wild-type seedlings, and this activity was not responsive to changes of M n nutrition in either genotype. Taken together, these results suggest that the manl mutation disrupts the regulation of metal-ion uptake or homeostasis in Arabidopsis.

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Cu2+ Reduction by Tomato Root Plasma Membrane Vesicles

Cited by 17 publications

References 16 publications

Ferric and cupric reductase activities in the green alga Chlamydomonas reinhardtii : experiments using iron-limited chemostats

Ferric and cupric reductase activities in the green alga Chlamydomonas reinhardtii : experiments using iron-limited chemostats

Regulated Copper Uptake in Chlamydomonas reinhardtii in Response to Copper Availability

A Metal-Accumulator Mutant of Arabidopsis thaliana

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