Characterization of a protein of the plastid inner envelope having homology to animal inorganic phosphate, chloride and organic-anion transporters

Roth, Christian; Menzel, Gerhard; Petétot, Jean MacDonald-Comber; Rochat-Hacker, Sylvie; Poirier, Yves

doi:10.1007/s00425-003-1121-5

Cited by 37 publications

(50 citation statements)

References 52 publications

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“…Like TPT, both of these Pi transporters are located in the chloroplast inner envelope membrane. 14,18 Also, transcript levels for the genes increased when plants were exposed to light, although the delay in PHT4;4 transcript accumulation may reflect regulation by photosynthates rather than a direct response to light. It is formally possible that PHT4;4 and PHT2;1 also maintain stromal Pi concentrations through export.…”

Section: Methodsmentioning

confidence: 99%

“…16 Proteomic analysis of the chloroplast envelope and envelope membrane fractionation studies confirmed that PHT4;4 is located in the chloroplast inner envelope membrane. 4,17,18 In contrast, PHT4;1 is located in the thylakoid membrane. 4 Despite the localization of these two proteins to chloroplast membranes, transcripts for all of the Arabidopsis PHT4 genes have been detected in roots as well as leaves suggesting that the encoded plastid-targeted proteins also function in non-photosynthetic plastids.…”

Section: Research Papermentioning

confidence: 97%

“…Functional studies in Escherichia coli suggest that at least one of these, PHT4;1, can also mediate Na + -dependent Pi transport. 4 Bioinformatics and localization of PHT4-GFP protein fusions indicate that five members of this family (PHT4;1 through PHT4;5) are targeted to plastids, [16][17][18] and the sixth, PHT4;6, resides in the Golgi apparatus. 16 Proteomic analysis of the chloroplast envelope and envelope membrane fractionation studies confirmed that PHT4;4 is located in the chloroplast inner envelope membrane.…”

Section: Research Papermentioning

confidence: 99%

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Differential expression and phylogenetic analysis suggest specialization of plastid-localized members of the PHT4 phosphate transporter family for photosynthetic and heterotrophic tissues

Guo

Irigoyen

Fowler

et al. 2008

Plant Signaling & Behavior

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Plastids rely on multiple phosphate (Pi) transport activities to support and control a wide range of metabolic processes, including photosynthesis and carbon partitioning. Five of the six members of the PHT4 family of Pi transporters in Arabidopsis thaliana (PHT4;1-PHT4;5) are confirmed or predicted plastid proteins. As a step towards identifying the roles of individual PHT4 Pi transporters in chloroplast and non-photosynthetic plastid Pi dynamics, we used promoter-reporter gene fusions and quantitative RT-PCR studies, respectively, to determine spatial and diurnal gene expression patterns. PHT4;1 and PHT4;4 were both expressed predominantly in photosynthetic tissues, although expression of PHT4;1 was circadian and PHT4;4 was induced by light. PHT4;3 and PHT4;5 were expressed mainly in leaf phloem. PHT4;2 was expressed throughout the root, and exhibited a diurnal pattern with peak transcript levels in the dark. The remaining member of this gene family, PHT4;6, encodes a Golgi-localized protein and was expressed ubiquitously. The overlapping but distinct expression patterns for these genes suggest specialized roles for the encoded transporters in multiple types of differentiated plastids. Phylogenetic analysis revealed conservation of each of the orthologous members of the PHT4 family in Arabidopsis and rice, which is consistent with specialization, and suggests that the individual members of this transporter family diverged prior to the divergence of monocots and dicots. IntroductionDynamic control of stromal inorganic phosphate (Pi) levels is central to the specialized metabolic functions of differentiated plastids. Notably, the concentration of Pi in the chloroplast stroma is tightly coordinated with environmental conditions to modulate both photosynthesis and the subsequent partitioning of fixed carbon. 1,2 Pi concentrations in amyloplasts also are held within a critical limit to prevent inhibition of starch biosynthesis. 3 For each plastid type, Pi concentrations are controlled through a combination of metabolic recycling in the stroma and surrounding cytosol, and the transport of Pi across the plastid limiting membrane. Recent data suggest that similar processes also link the Pi status of the chloroplast stroma and thylakoid lumen. 4 Plastidic Pi transport is generally attributed to members of the plastidic phosphate translocator (pPT) family. 5 These proteins are located in the inner envelope membrane and mediate strict counterexchange of Pi for phosphorylated C3, C5 or C6 compounds. The triose phosphate/Pi translocator (TPT) was the first pPT protein to be identified, and it is expressed almost exclusively in photosynthetic tissues where it catalyzes transport of cytosolic Pi into the chloroplast in exchange for triose phosphates, the end products of photosynthesis. 6 This activity represents the major pathway for carbon allocation to the cytosol during the day as well as the primary route for Pi import into the chloroplast. Related members of the pPT family include the phosphoenolpyruvate/Pi translocator...

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Section: Methodsmentioning

confidence: 99%

Section: Research Papermentioning

confidence: 97%

Section: Research Papermentioning

confidence: 99%

See 1 more Smart Citation

Differential expression and phylogenetic analysis suggest specialization of plastid-localized members of the PHT4 phosphate transporter family for photosynthetic and heterotrophic tissues

Guo

Irigoyen

Fowler

et al. 2008

Plant Signaling & Behavior

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“…We found two candidates that differed in transcript abundance for P i transporters (PHT4.4 and PHO1-H8) and one misexpressed K + efflux transporter (KEA1) (see Supplemental Tables 4 and 5 online). All three transcripts were more highly expressed in the mesophyll; however, PHT4.4 has previously been localized to the chloroplast (Roth et al, 2004), and PHO1-H8 and KEA1 are predicted to be targeted to the mitochondria and chloroplast, respectively (SUBA database) (Heazlewood et al, 2007). Further support for the role of KEA1 in chloroplasts comes from its closest two homologs in barley also being highly expressed in the mesophyll (Richardson et al, 2007).…”

Section: Cell-specific Ca Compartmentation Involves Cell-specific Sementioning

confidence: 99%

Cell-Specific Vacuolar Calcium Storage Mediated by CAX1 Regulates Apoplastic Calcium Concentration, Gas Exchange, and Plant Productivity in Arabidopsis

et al. 2011

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The physiological role and mechanism of nutrient storage within vacuoles of specific cell types is poorly understood. Transcript profiles from Arabidopsis thaliana leaf cells differing in calcium concentration ([Ca], epidermis <10 mM versus mesophyll >60 mM) were compared using a microarray screen and single-cell quantitative PCR. Three tonoplast-localized Ca 2+ transporters, CAX1 (Ca 2+ /H + -antiporter), ACA4, and ACA11 (Ca 2+ -ATPases), were identified as preferentially expressed in Ca-rich mesophyll. Analysis of respective loss-of-function mutants demonstrated that only a mutant that lacked expression of both CAX1 and CAX3, a gene ectopically expressed in leaves upon knockout of CAX1, had reduced mesophyll [Ca]. Reduced capacity for mesophyll Ca accumulation resulted in reduced cell wall extensibility, stomatal aperture, transpiration, CO 2 assimilation, and leaf growth rate; increased transcript abundance of other Ca 2+ transporter genes; altered expression of cell wall-modifying proteins, including members of the pectinmethylesterase, expansin, cellulose synthase, and polygalacturonase families; and higher pectin concentrations and thicker cell walls. We demonstrate that these phenotypes result from altered apoplastic free [Ca 2+ ], which is threefold greater in cax1/cax3 than in wild-type plants. We establish CAX1 as a key regulator of apoplastic [Ca 2+ ] through compartmentation into mesophyll vacuoles, a mechanism essential for optimal plant function and productivity.

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“…The theoretical molecular mass of the processed protein is 50.5 kD, which differs significantly from the 35 kD estimated from SDS-PAGE. Two other members of the PHT4 family, PHT4;1 and PHT4;4, also exhibit anomalous migration by SDS-PAGE (Roth et al, 2004;Ruiz Pavó n et al, 2008). The faster gel migrations of PHT4;2 and these other PHT4 proteins may be a function of overproportional binding of SDS, which is common for highly hydrophobic integral membrane proteins (Rath et al, 2009).…”

Section: Localization Of Pht4;2 To Root Plastidsmentioning

confidence: 99%

The Sink-Specific Plastidic Phosphate Transporter PHT4;2 Influences Starch Accumulation and Leaf Size in Arabidopsis

et al. 2011

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Nonphotosynthetic plastids are important sites for the biosynthesis of starch, fatty acids, and amino acids. The uptake and subsequent use of cytosolic ATP to fuel these and other anabolic processes would lead to the accumulation of inorganic phosphate (Pi) if not balanced by a Pi export activity. However, the identity of the transporter(s) responsible for Pi export is unclear. The plastid-localized Pi transporter PHT4;2 of Arabidopsis (Arabidopsis thaliana) is expressed in multiple sink organs but is nearly restricted to roots during vegetative growth. We identified and used pht4;2 null mutants to confirm that PHT4;2 contributes to Pi transport in isolated root plastids. Starch accumulation was limited in pht4;2 roots, which is consistent with the inhibition of starch synthesis by excess Pi as a result of a defect in Pi export. Reduced starch accumulation in leaves and altered expression patterns for starch synthesis genes and other plastid transporter genes suggest metabolic adaptation to the defect in roots. Moreover, pht4;2 rosettes, but not roots, were significantly larger than those of the wild type, with 40% greater leaf area and twice the biomass when plants were grown with a short (8-h) photoperiod. Increased cell proliferation accounted for the larger leaf size and biomass, as no changes were detected in mature cell size, specific leaf area, or relative photosynthetic electron transport activity. These data suggest novel signaling between roots and leaves that contributes to the regulation of leaf size.

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Characterization of a protein of the plastid inner envelope having homology to animal inorganic phosphate, chloride and organic-anion transporters

Cited by 37 publications

References 52 publications

Differential expression and phylogenetic analysis suggest specialization of plastid-localized members of the PHT4 phosphate transporter family for photosynthetic and heterotrophic tissues

Differential expression and phylogenetic analysis suggest specialization of plastid-localized members of the PHT4 phosphate transporter family for photosynthetic and heterotrophic tissues

Cell-Specific Vacuolar Calcium Storage Mediated by CAX1 Regulates Apoplastic Calcium Concentration, Gas Exchange, and Plant Productivity in Arabidopsis

The Sink-Specific Plastidic Phosphate Transporter PHT4;2 Influences Starch Accumulation and Leaf Size in Arabidopsis

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