Glutamine and Glutamate Transport in <i>Cyanophora paradoxa</i>

Kloos, Karin; Schlichting, Ralf; Zimmer, W.; Bothe, Hermann

doi:10.1111/j.1438-8677.1993.tb00771.x

Cited by 8 publications

(7 citation statements)

References 33 publications

(25 reference statements)

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“…The DiTs [ 39 ] are present only in green algae, plants, and bacteria (that is, not in red algae). Whereas genomic data for glaucophytes are not yet available, transport experiments using isolated Cyanophora cyanelles showed that this glaucophyte uses a transport system for glutamine and 2-oxoglutarate that is distinct from green plant DiTs [ 40 ]. Taken together, these data indicate that ' Chlamydia -like' dicarboxylate translocators have likely been lost from red algae and glaucophytes.…”

Section: Resultsmentioning

confidence: 99%

Host origin of plastid solute transporters in the first photosynthetic eukaryotes

et al. 2007

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Background: It is generally accepted that a single primary endosymbiosis in the Plantae (red, green (including land plants), and glaucophyte algae) common ancestor gave rise to the ancestral photosynthetic organelle (plastid). Plastid establishment necessitated many steps, including the transfer and activation of endosymbiont genes that were relocated to the nuclear genome of the 'host' followed by import of the encoded proteins into the organelle. These innovations are, however, highly complex and could not have driven the initial formation of the endosymbiosis. We postulate that the re-targeting of existing host solute transporters to the plastid fore-runner was critical for the early success of the primary endosymbiosis, allowing the host to harvest endosymbiont primary production.

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Section: Resultsmentioning

confidence: 99%

Host origin of plastid solute transporters in the first photosynthetic eukaryotes

et al. 2007

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“…Phylogenetic surveys indicate that the dicarboxylate transporters are of chlamydial origin, reinforcing the hypothesis on the importance these intracellular parasites had in the establishment of endosymbiosis (Tyra et al, 2007 ). In isolated C. paradoxa muroplasts, transport activities for glutamine and 2-oxoglutarate could be measured (Kloos et al, 1993 ). In uptake experiments with isolated cyanelles by silicone oil filtering it could be shown that glutamate poorly penetrated into cyanelles, whereas glutamine was enriched in the plastid fraction by 1.7 fold within 10 min.…”

Section: Other Transportersmentioning

confidence: 99%

“…In uptake experiments with isolated cyanelles by silicone oil filtering it could be shown that glutamate poorly penetrated into cyanelles, whereas glutamine was enriched in the plastid fraction by 1.7 fold within 10 min. Glutamine uptake proceeded in two phases and was stimulated by 2-oxoglutarate (Kloos et al, 1993 ). Ammonia formed by nitrite reduction inside the cyanelles is incorporated by GS into glutamine and then exported jointly with oxoglutarate (Kloos et al, 1993 ).…”

Section: Other Transportersmentioning

confidence: 99%

The Metabolite Transporters of the Plastid Envelope: An Update

Facchinelli¹,

Weber²

2011

Front. Plant Sci.

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The engulfment of a photoautotrophic cyanobacterium by a primitive mitochondria-bearing eukaryote traces back to more than 1.2 billion years ago. This single endosymbiotic event not only provided the early petroalgae with the metabolic capacity to perform oxygenic photosynthesis, but also introduced a plethora of other metabolic routes ranging from fatty acids and amino acids biosynthesis, nitrogen and sulfur assimilation to secondary compounds synthesis. This implicated the integration and coordination of the newly acquired metabolic entity with the host metabolism. The interface between the host cytosol and the plastidic stroma became of crucial importance in sorting precursors and products between the plastid and other cellular compartments. The plastid envelope membranes fulfill different tasks: they perform important metabolic functions, as they are involved in the synthesis of carotenoids, chlorophylls, and galactolipids. In addition, since most genes of cyanobacterial origin have been transferred to the nucleus, plastidial proteins encoded by nuclear genes are post-translationally transported across the envelopes through the TIC–TOC import machinery. Most importantly, chloroplasts supply the photoautotrophic cell with photosynthates in form of reduced carbon. The innermost bilayer of the plastidic envelope represents the permeability barrier for the metabolites involved in the carbon cycle and is literally stuffed with transporter proteins facilitating their transfer. The intracellular metabolite transporters consist of polytopic proteins containing membrane spans usually in the number of four or more α-helices. Phylogenetic analyses revealed that connecting the plastid with the host metabolism was mainly a process driven by the host cell. In Arabidopsis, 58% of the metabolite transporters are of host origin, whereas only 12% are attributable to the cyanobacterial endosymbiont. This review focuses on the metabolite transporters of the inner envelope membrane of plastids, in particular the electrochemical potential-driven class of transporters. Recent advances in elucidating the plastidial complement of metabolite transporters are provided, with an update on phylogenetic relationship of selected proteins.

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“…Cyanelles have recently been shown to perform photorespiration (Betsche et al, 1992), thus transport of glyoxylate and/or other compounds is to be expected. Cyanelles transport amino acids by specific carriers which is described in the accompanying paper (Kloos et al, 1993).…”

Section: Discussionmentioning

confidence: 99%

“…The previous results (Schlichting et ai.,1990) indicated that cyanelles possess neither a malate/oxaloacetate carrier nor an ATP/ ADPtranslocator. This communication describes properties of a phosphate translocator and a glucose carrier in the cytoplasmic membrane of cyanelles whereas the accompanying paper (Kloos et al, 1993) characterizes the exchange of nitrogenous compounds from and to cyanelles.…”

mentioning

confidence: 99%

The Cyanelles (Organelles of a Low Evolutionary Scale) Possess a Phosphate‐Translocator and a Glucose‐Carrier in Cyanophora paradoxa

Schlichting

Bothe

1993

Botanica Acta

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Cyanelles from Cyanophora paradoxa can easily be isolated and assayed for their carrier composition by the silicone oil filtering technique. The present investigation demonstrates a Pi‐translocator transferring phosphate, dihydroxyacetone phosphate and 3‐phosphoglycerate in a counter exchange mode in cyanelles as in chloroplasts of higher plants. The uptake of Pi is inhibited by dihydroxyacetone phosphate, phosphoglycerate and glucose‐6‐P, only poorly by phosphoenolpyruvate and not by 2‐phosphoglycerate. The inhibitors pyridoxalphosphate and 4,4′diisothiocyanostilbene‐2,2K'disulfonic acid at low concentration also affect Pi‐uptake. Cyanelles probably transport photosynthate (reductant and ATP) by triosephosphates. This is the first demonstration of a phosphate translocator in an organism of a low evolutionary scale. Cyanelles also transport glucose which proceeds in two phases. In the lower concentration range (≤ 2.5 mM), glucose penetrates by facilitated diffusion, whereas transport follows first‐order kinetics at higher amounts (> 2.5 mM). In the low concentration range, glucose‐transport is affected by high concentrations of 3‐O‐methylglucose and fructose. The physiological role of the glucose‐transport carrier in Cyanophora is doubtful. It may function in transporting glucose into cyanelles if the carbon level inside them becomes limiting, e.g. in dark periods.

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Glutamine and Glutamate Transport in Cyanophora paradoxa

Cited by 8 publications

References 33 publications

Host origin of plastid solute transporters in the first photosynthetic eukaryotes

Host origin of plastid solute transporters in the first photosynthetic eukaryotes

The Metabolite Transporters of the Plastid Envelope: An Update

The Cyanelles (Organelles of a Low Evolutionary Scale) Possess a Phosphate‐Translocator and a Glucose‐Carrier in Cyanophora paradoxa

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