The vacuolar malate transporter of Kalanchoë daigremontiana: A 32 kDa polypeptide?

Steiger, Sabine; Pfeifer, Tanja; Ratajczak, Rafael; Martinoia, Enrico; Lüttge, Ulrich

doi:10.1016/s0176-1617(97)80145-9

Cited by 19 publications

(5 citation statements)

References 18 publications

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“…A biochemical approach to isolate the corresponding protein is extremely hampered by the low number of tonoplast membranes usually enriched from plant tissues (18,19).…”

Section: Resultsmentioning

confidence: 99%

The plant homolog to the human sodium/dicarboxylic cotransporter is the vacuolar malate carrier

Emmerlich

Linka²,

Reinhold³

et al. 2003

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

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162

158

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Malate plays a central role in plant metabolism. It is an intermediate in the Krebs and glyoxylate cycles, it is the store for CO2 in C4 and crassulacean acid metabolism plants, it protects plants from aluminum toxicity, it is essential for maintaining the osmotic pressure and charge balance, and it is therefore involved in regulation of stomatal aperture. To fulfil many of these roles, malate has to be accumulated within the large central vacuole.

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“…A biochemical approach to isolate the corresponding protein is extremely hampered by the low number of tonoplast membranes usually enriched from plant tissues (18,19).…”

Section: Resultsmentioning

confidence: 99%

The plant homolog to the human sodium/dicarboxylic cotransporter is the vacuolar malate carrier

Emmerlich

Linka²,

Reinhold³

et al. 2003

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

Self Cite

162

158

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“…In a biochemical characterization of tonoplast proteins in K. daigremontiana , Ratajczak et al . (1994) and Steiger et al . (1997) succeeded in achieving partial purification of malate transport activity after incorporation of a polypeptide fraction in the 32–34 kDa mass range into liposomes.…”

Section: Discussionmentioning

confidence: 96%

“…Attempts to identify the transport system responsible for vacuolar malate influx have been made by means of comparative physiology, protein biochemistry, transport studies with membrane vesicles, and patch‐clamp electrophysiology (reviewed in Lüttge et al ., 2000). Although partial enrichment of the transport system has been achieved, the component polypeptides have not been identified so far using biochemical approaches (Martinoia et al ., 1991; Steiger et al ., 1997). Many physiological experiments with membrane vesicles and isolated vacuoles have demonstrated the existence of a malate transport system with saturable kinetics at the tonoplast (Lüttge et al ., 2000; Martinoia and Rentsch, 1994; Smith et al ., 1996).…”

Section: Introductionmentioning

confidence: 99%

Vacuolar malate uptake is mediated by an anion‐selective inward rectifier

Hafke

Smith

et al. 2003

The Plant Journal

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SummaryElectrophysiological studies using the patch-clamp technique were performed on isolated vacuoles from leaf mesophyll cells of the crassulacean acid metabolism (CAM) plant Kalanchoe¨daigremontiana to characterize the malate transport system responsible for nocturnal malic acid accumulation. In the presence of malate on both sides of the membrane, the current-voltage relations of the tonoplast were dominated by a strongly inward-rectifying anion-selective channel that was active at cytoplasmic-side negative voltages. Rectification of the macroscopic conductance was reflected in the voltage-dependent gating of a 3-pS malate-selective ion channel, which showed a half-maximal open probability at À43 mV. Also, the timeaveraged unitary currents following a step to a negative voltage corresponded to the time-dependent kinetics of the macroscopic currents, suggesting that the activity of this channel underlies the anion-selective inward rectifier. The inward rectifier showed saturation kinetics with respect to malate (apparent K m of 2.5 mM malate 2À activity), a selectivity sequence of fumarate 2À > malate 2À > Cl À > maleate 2-% citrate 3-, and greater activity at higher pH values (with an apparent pK of 7.1 and maximum activity at around pH 8.0). All these properties were in close agreement with the characteristics of malate transport observed in isolated tonoplast vesicles. Further, 100 mM niflumate reversibly blocked the activity of the 3-pS channel and inhibited both macroscopic currents and malate transport into tonoplast vesicles to the same extent. The macroscopic current densities recorded at physiological voltages and the estimated channel density of 0.2 lm À2 are sufficient to account for the observed rates of nocturnal malic acid accumulation in this CAM plant, suggesting that the 3-pS, inward-rectifying, anion-selective channel represents the principal pathway for malate influx into the vacuole.

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“…A strategy to analyse differences in polypeptide expression patterns in C 3 -versus CAM-performing leaves of M. crystallinum is being used to identify vacuolar malate transporters. Antisera raised against affinity-chromatography-purified tonoplast vesicle fractions from K. daigremontiana enriched for malate transport activity have been used to identify 32 and 33 kDa ice plant polypeptides that are induced or enhanced in the CAM state (Steiger et al 1997;Lüttge et al 2000). These lowabundance polypeptides are strong candidates for the vacuolar malate transporter, from which amino acid sequence information could be obtained and used to design degenerate oligonucleotides via back-translation to facilitate the isolation of the corresponding genes.…”

Section: Circadian Control Of Carbon Fluxmentioning

confidence: 99%

Induction of Crassulacean acid metabolism by water limitation

Cushman

Borland

2002

Plant Cell & Environment

141

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Crassulacean acid metabolism (CAM), a key adaptation of photosynthetic carbon fixation to limited water availability, is characterized by nocturnal CO 2 fixation and daytime CO 2 re-assimilation, which generally results in improved wateruse efficiency. However, CAM plants display a remarkable degree of photosynthetic plasticity within a continuum of diel gas exchange patterns. Genotypic, ontogenetic and environmental factors combine to govern the extent to which CAM is expressed. The ecological diversity of CAM is mirrored by plasticity in a range of biochemical and physiological attributes. In C 3 /CAM-intermediate plants, limited water availability can induce or enhance the expression of CAM. CAM induction is controlled by a combination of transcriptional, post-transcriptional and post-translational regulatory events. Early events in CAM induction point to a requirement for calcium and calcium-dependent protein kinase activities. Gene discovery efforts, improved transformation technologies and genetic models for CAM plants, coupled with detailed physiological investigations, will lead to new insights into the molecular genetic basis of induction processes and the circadian oscillator that governs carbon flux during CAM. Future integration of genomic, biochemical and physiological approaches in selected CAM models promise to provide a detailed view of the complex regulatory dynamics involved in CAM induction and modulation by water deficit. Such information is expected to have broad significance as the ecological and agricultural importance of CAM species increases in the face of global warming trends and the associated expansion of desertification in semi-arid regions around the world.

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The vacuolar malate transporter of Kalanchoë daigremontiana: A 32 kDa polypeptide?

Cited by 19 publications

References 18 publications

The plant homolog to the human sodium/dicarboxylic cotransporter is the vacuolar malate carrier

The plant homolog to the human sodium/dicarboxylic cotransporter is the vacuolar malate carrier

Vacuolar malate uptake is mediated by an anion‐selective inward rectifier

Induction of Crassulacean acid metabolism by water limitation

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