A New Class of Plastidic Phosphate Translocators: A Putative Link between Primary and Secondary Metabolism by the Phosphoenolpyruvate/Phosphate Antiporter

Fischer, Karsten; Kammerer, Birgit; Gutensohn, Michael; Arbinger, Bettina; Weber, Andreas; Häusler, Rainer E.; Flügge, Ulf‐Ingo

doi:10.2307/3870494

Cited by 82 publications

(131 citation statements)

References 14 publications

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“…In agreement with these observations, GPT had higher EST abundance in the "seeds" library pool than the reference at P Ͻ 0.004. Similarly, for PPT, biochemical analysis and mRNA-blotting results indicated a high expression of PPT in nongreen tissue (Kammerer et al, 1998), especially roots (Fischer et al, 1997), and in our EST analysis, PPT expression was highest in the "roots" (P Ͻ 0.003). Thus, the comparisons in Table III agree with previous biochemical characterizations and support the validity of the digital expression profile approach.…”

Section: Digital Mrna Expression Profilementioning

confidence: 90%

The Predicted Candidates of Arabidopsis Plastid Inner Envelope Membrane Proteins and Their Expression Profiles,

Koo

Ohlrogge

2002

Plant Physiology

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Plastid envelope proteins from the Arabidopsis nuclear genome were predicted using computational methods. Selection criteria were: first, to find proteins with NH 2 -terminal plastid-targeting peptides from all annotated open reading frames from Arabidopsis; second, to search for proteins with membrane-spanning domains among the predicted plastidial-targeted proteins; and third, to subtract known thylakoid membrane proteins. Five hundred forty-one proteins were selected as potential candidates of the Arabidopsis plastid inner envelope membrane proteins (AtPEM candidates). Only 34% (183) of the AtPEM candidates could be assigned to putative functions based on sequence similarity to proteins of known function (compared with the 69% function assignment of the total predicted proteins in the genome). Of the 183 candidates with assigned functions, 40% were classified in the category of "transport facilitation," indicating that this collection is highly enriched in membrane transporters. Information on the predicted proteins, tissue expression data from expressed sequence tags and microarrays, and publicly available T-DNA insertion lines were collected. The data set complements proteomic-based efforts in the increased detection of integral membrane proteins, low-abundance proteins, or those not expressed in tissues selected for proteomic analysis. Digital northern analysis of expressed sequence tags suggested that the transcript levels of most AtPEM candidates were relatively constant among different tissues in contrast to stroma and the thylakoid proteins. However, both digital northern and microarray analyses identified a number of AtPEM candidates with tissue-specific expression patterns.Plastids exist in a wide range of differential forms, including proplastids, chloroplasts, etioplasts, amyloplasts, leucoplasts, and chromoplasts, depending on the developmental stage and function of the plant cells in which they reside. To a large extent, the types of plastids that are carried by cells determine the metabolic function and products of the particular plant tissue (Kirk and Tilney-Bassett, 1978).One constant feature among the various types of plastids is the double membrane envelope structure that surrounds the organelle. The envelope, especially the inner envelope, effectively separates plastid metabolism from that of the cytosol. At the same time, almost all carbon and a major flux of other metabolites, various polypeptides, and signals must move through the envelope to coordinate and integrate metabolism with the entire cell. Plastid envelopes contain protein transport machinery (Schnell, 1995;Cline and Henry, 1996;Heins et al., 1998), and are a major site for membrane biogenesis. Metabolite transporters from chloroplast and/or nongreen plastids accommodate the requirements of the different photosynthetic or heterotrophic tissues (Kammerer et al., 1998;Neuhaus and Emes, 2000). Membrane constituents (glycerolipids, pigments, and prenylquinones) are synthesized on the envelope membrane as well as the porphyrin ring ...

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Section: Digital Mrna Expression Profilementioning

confidence: 90%

The Predicted Candidates of Arabidopsis Plastid Inner Envelope Membrane Proteins and Their Expression Profiles,

Koo

Ohlrogge

2002

Plant Physiology

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“…Niewiadomski et al (2005) have shown that the loss of GPT1 function results in a disruption of the oxidative pentose phosphate cycle and affects fatty acid biosynthesis. Another translocator, phosphoenolpyruvate phosphate translocator (Solyc03g112870), has been identified that delivers the energy-rich glycolytic intermediate phosphoenolpyruvate into the plastids (Fischer et al, 1997). In addition, a triose phosphate/phosphate translocator (Solyc10g008980) has also been encountered that participates in Suc biosynthesis (Cho et al, 2012).…”

Section: Proteins Involved In Energy Provision and Translocation Actimentioning

confidence: 99%

Proteomic Analysis of Chloroplast-to-Chromoplast Transition in Tomato Reveals Metabolic Shifts Coupled with Disrupted Thylakoid Biogenesis Machinery and Elevated Energy-Production Components

et al. 2012

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A comparative proteomic approach was performed to identify differentially expressed proteins in plastids at three stages of tomato (Solanum lycopersicum) fruit ripening (mature-green, breaker, red). Stringent curation and processing of the data from three independent replicates identified 1,932 proteins among which 1,529 were quantified by spectral counting. The quantification procedures have been subsequently validated by immunoblot analysis of six proteins representative of distinct metabolic or regulatory pathways. Among the main features of the chloroplast-to-chromoplast transition revealed by the study, chromoplastogenesis appears to be associated with major metabolic shifts: (1) strong decrease in abundance of proteins of light reactions (photosynthesis, Calvin cycle, photorespiration) and carbohydrate metabolism (starch synthesis/degradation), mostly between breaker and red stages and (2) increase in terpenoid biosynthesis (including carotenoids) and stress-response proteins (ascorbate-glutathione cycle, abiotic stress, redox, heat shock). These metabolic shifts are preceded by the accumulation of plastid-encoded acetyl Coenzyme A carboxylase D proteins accounting for the generation of a storage matrix that will accumulate carotenoids. Of particular note is the high abundance of proteins involved in providing energy and in metabolites import. Structural differentiation of the chromoplast is characterized by a sharp and continuous decrease of thylakoid proteins whereas envelope and stroma proteins remain remarkably stable. This is coincident with the disruption of the machinery for thylakoids and photosystem biogenesis (vesicular trafficking, provision of material for thylakoid biosynthesis, photosystems assembly) and the loss of the plastid division machinery. Altogether, the data provide new insights on the chromoplast differentiation process while enriching our knowledge of the plant plastid proteome.

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“…Related members of the pPT family include the phosphoenolpyruvate/Pi translocator (PPT), glucose 6-phosphate/ Pi translocator (GPT) and xylulose 5-phosphate/Pi translocator (XPT). [7][8][9] In contrast to TPT, these translocators export Pi from plastids in exchange for cytosolic metabolites that serve as precursors for biosynthetic processes within the stroma. Moreover, PPT and XPT are expressed in both photosynthetic and heterotrophic tissues, and GPT expression is restricted to heterotrophic tissues.…”

Section: Introductionmentioning

confidence: 99%

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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A New Class of Plastidic Phosphate Translocators: A Putative Link between Primary and Secondary Metabolism by the Phosphoenolpyruvate/Phosphate Antiporter

Cited by 82 publications

References 14 publications

The Predicted Candidates of Arabidopsis Plastid Inner Envelope Membrane Proteins and Their Expression Profiles,

The Predicted Candidates of Arabidopsis Plastid Inner Envelope Membrane Proteins and Their Expression Profiles,

Proteomic Analysis of Chloroplast-to-Chromoplast Transition in Tomato Reveals Metabolic Shifts Coupled with Disrupted Thylakoid Biogenesis Machinery and Elevated Energy-Production Components

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

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