Characterization of two functional phosphoenolpyruvate/phosphate translocator (PPT) genes in Arabidopsis–AtPPT1 may be involved in the provision of signals for correct mesophyll development

Knappe, Silke; Löttgert, Tanja; Schneider, Anja; Voll, Lars M.; Flügge, Ulf‐Ingo; Fischer, Karsten

doi:10.1046/j.1365-313x.2003.01888.x

Cited by 98 publications

(151 citation statements)

References 53 publications

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“…Consistently we observed that the PEP/P i translocator (PPT), located in the inner chloroplast envelope membrane, accumulated with a low BS/M ratio of 0.21 (TC286421). PPT homologues in Arabidopsis were shown to be expressed specifically in the mesophyll cells (PPT1) or veins (PPT2) and are required for formation of mesophyll tissue (124).…”

Section: Purification Of M and Bs Chloroplast Membranes Frommentioning

confidence: 99%

Consequences of C4 Differentiation for Chloroplast Membrane Proteomes in Maize Mesophyll and Bundle Sheath Cells

Majeran

Zybailov

Ytterberg

et al. 2008

Molecular & Cellular Proteomics

195

205

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Chloroplasts of maize leaves differentiate into specific bundle sheath (BS) and mesophyll (M) types to accommodate C 4 photosynthesis. Chloroplasts contain thylakoid and envelope membranes that contain the photosynthetic machineries and transporters but also proteins involved in e.g. protein homeostasis. These chloroplast membranes must be specialized within each cell type to accommodate C 4 photosynthesis and regulate metabolic fluxes and activities. This quantitative study determined the differentiated state of BS and M chloroplast thylakoid and envelope membrane proteomes and their oligomeric states using innovative gel-based and mass spectrometry-based protein quantifications. This included native gels, iTRAQ, and label-free quantification using an LTQ-Orbitrap. Subunits of Photosystems I and II, the cytochrome b 6 f, and ATP synthase complexes showed average BS/M accumulation ratios of 1.6, 0.45, 1.0, and 1.33, respectively, whereas ratios for the light-harvesting complex I and II families were 1.72 and 0.68, respectively. A 1000-kDa BS-specific NAD(P)H dehydrogenase complex with associated proteins of unknown function containing more than 15 proteins was observed; we speculate that this novel complex possibly functions in inorganic carbon concentration when carboxylation rates by ribulose-bisphosphate carboxylase/oxygenase are lower than decarboxylation rates by malic enzyme. In leaves of C 4 grasses such as maize (Zea mays), photosynthetic activities are partitioned between two morphologically and biochemically distinct bundle sheath (BS) 1 and mesophyll (M) cells. A single ring of BS cells surrounds the vascular bundle followed by a concentric ring of specialized M cells, creating the classical Kranz anatomy. C 4 differentiation occurs along a developmental gradient with proplastids at the leaf base and fully differentiated C 4 M and BS chloroplasts at the leaf tip. Genetic screens for mutants affected in BS differentiation identified various mutants (1-4). However, the molecular basis for C 4 differentiation is still poorly understood but includes transcriptional regulation through DNA regulatory elements, transcription factors, and likely also metabolic signals (5, 6). Differential accumulation of thylakoid proteases (Egy andDegP

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Section: Purification Of M and Bs Chloroplast Membranes Frommentioning

confidence: 99%

Consequences of C4 Differentiation for Chloroplast Membrane Proteomes in Maize Mesophyll and Bundle Sheath Cells

Majeran

Zybailov

Ytterberg

et al. 2008

Molecular & Cellular Proteomics

195

205

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“…PPT genes are expressed at low levels in various tissues (Knappe et al, 2003b). To determine the expression pattern of GspPTs, semiquantitative reverse transcription-PCR was used.…”

Section: Gsgptmentioning

confidence: 99%

“…Import of phosphoenolpyruvic acid (PEP) from the cytosol by the PEP/phosphate transporter (PPT) drives fatty acid biosynthesis and synthesis of compounds by the shikimate pathway (i.e. aromatic amino acids; Fischer et al, 1997;Knappe et al, 2003b;Voll et al, 2003) and a Glc-6-P/phosphate transporter (GPT) provides Glc-6-P for starch synthesis in heterotrophic plastids (Kammerer et al, 1998;Niewiadomski et al, 2005). Last, a protein closely related to the GPT, the pentose-P/phosphate transporter (XPT), connects the oxidative pentose-P pathways (OPPPs) in cytosol and plastid (Eicks et al, 2002;Flü gge and Gao, 2005).…”

mentioning

confidence: 99%

Functional Characterization of the Plastidic Phosphate Translocator Gene Family from the Thermo-Acidophilic Red Alga Galdieria sulphuraria Reveals Specific Adaptations of Primary Carbon Partitioning in Green Plants and Red Algae

2008

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In chloroplasts of green plants and algae, CO 2 is assimilated into triose-phosphates (TPs); a large part of these TPs is exported to the cytosol by a TP/phosphate translocator (TPT), whereas some is stored in the plastid as starch. Plastidial phosphate translocators have evolved from transport proteins of the host endomembrane system shortly after the origin of chloroplasts by endosymbiosis. The red microalga Galdieria sulphuraria shares three conserved putative orthologous transport proteins with the distantly related seed plants and green algae. However, red algae, in contrast to green plants, store starch in their cytosol, not inside plastids. Hence, due to the lack of a plastidic starch pool, a larger share of recently assimilated CO 2 needs to be exported to the cytosol. We thus hypothesized that red algal transporters have distinct substrate specificity in comparison to their green orthologs. This hypothesis was tested by expression of the red algal genes in yeast (Saccharomyces cerevisiae) and assessment of their substrate specificities and kinetic constants. Indeed, two of the three red algal phosphate translocator candidate orthologs have clearly distinct substrate specificities when compared to their green homologs. GsTPT (for G. sulphuraria TPT) displays very narrow substrate specificity and high affinity; in contrast to green plant TPTs, 3-phosphoglyceric acid is poorly transported and thus not able to serve as a TP/3-phosphoglyceric acid redox shuttle in vivo. Apparently, the specific features of red algal primary carbon metabolism promoted the evolution of a highly efficient export system with high affinities for its substrates. The low-affinity TPT of plants maintains TP levels sufficient for starch biosynthesis inside of chloroplasts, whereas the red algal TPT is optimized for efficient export of TP from the chloroplast.

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“…Transformants were selected with kanamycin and verified by PCR analysis. Histochemical localization of GUS activity was performed as described previously [19].…”

Section: Plant Transformation and Gene Expression Analysismentioning

confidence: 99%

Characterization of AtNST‐KT1, a novel UDP‐galactose transporter from Arabidopsis thaliana

et al. 2006

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Nucleotide sugar transporters (NST) mediate the transfer of nucleotide sugars from the cytosol into the lumen of the endoplasmatic reticulum and the Golgi apparatus. Because the NSTs show similarities with the plastidic phosphate translocators (pPTs), these proteins were grouped into the TPT/NST superfamily. In this study, a member of the NST-KT family, AtNST-KT1, was functionally characterized by expression of the corresponding cDNA in yeast cells and subsequent transport experiments. The histidine-tagged protein was purified by affinity chromatography and reconstituted into proteoliposomes. The substrate specificity of AtNST-KT1 was determined by measuring the import of radiolabelled nucleotide mono phosphates into liposomes preloaded with various unlabelled nucleotide sugars. This approach has the advantage that only one substrate has to be used in a radioactively labelled form while all the nucleotide sugars can be provided unlabelled. It turned out that AtNST-KT1 represents a monospecific NST transporting UMP in counterexchange with UDP-Gal but did not transport other nucleotide sugars. The AtNST-KT1 gene is ubiquitously expressed in all tissues. AtNST-KT1 is localized to Golgi membranes. Thus, AtNST-KT1 is most probably involved in the synthesis of galactose-containing glyco-conjugates in plants.

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Characterization of two functional phosphoenolpyruvate/phosphate translocator (PPT) genes in Arabidopsis–AtPPT1 may be involved in the provision of signals for correct mesophyll development

Cited by 98 publications

References 53 publications

Consequences of C4 Differentiation for Chloroplast Membrane Proteomes in Maize Mesophyll and Bundle Sheath Cells

Consequences of C4 Differentiation for Chloroplast Membrane Proteomes in Maize Mesophyll and Bundle Sheath Cells

Functional Characterization of the Plastidic Phosphate Translocator Gene Family from the Thermo-Acidophilic Red Alga Galdieria sulphuraria Reveals Specific Adaptations of Primary Carbon Partitioning in Green Plants and Red Algae

Characterization of AtNST‐KT1, a novel UDP‐galactose transporter from Arabidopsis thaliana

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