scholarly journals Evidence for two types of phosphate translocators in sweet-pepper (Capsicum annum L.) fruit chromoplasts

1996 ◽  
Vol 320 (1) ◽  
pp. 7-10 ◽  
Author(s):  
Paul W. QUICK ◽  
H. Ekkehard NEUHAUS
Keyword(s):  
Physiological Function ◽  
Sweet Pepper ◽  
Dihydroxyacetone Phosphate ◽  
Envelope Membrane ◽  
External Concentration ◽  
Capsicum Annum ◽  
Phosphate Translocator ◽  
Pepper Fruit ◽  
Different Types ◽  
Envelope Membranes

We have investigated whether there is evidence for the presence of different types of phosphate translocators in envelopes purified from pepper-fruit chromoplasts. A method was developed that allowed the purification of envelope membranes from isolated pepper-fruit chromoplasts. Proteoliposomes containing envelope-membrane proteins are able to import inorganic phosphate (Pi) or glucose 6-phosphate (Glc6P). In both cases, the rate of import is strongly dependent upon preloading of proteoliposomes with either Pi, dihydroxyacetone phosphate (DHAP) or Glc6P. This demonstrates the presence of a phosphate translocator activity catalysing a counter exchange of phosphorylated intermediates. Interestingly, a high external concentration of Glc6P does not strongly inhibit Pi uptake into proteoliposomes preloaded with DHAP, whereas external Glc6P strongly inhibits Pi uptake into proteoliposomes preloaded with Glc6P. This observation strongly indicates that two types of phosphate translocator are present in chromoplast envelopes from red-pepper fruits. These data are discussed with respect to the possible physiological function of two types of phosphate translocator in one type of plastid.

scholarly journals Reconstitution of the hexose phosphate translocator from the envelope membranes of wheat endosperm amyloplasts

1996 ◽  
Vol 319 (3) ◽  
pp. 717-723 ◽  
Author(s):  
Ian J TETLOW ◽  
Caroline G BOWSHER ◽  
Michael J EMES
Keyword(s):  
Inorganic Phosphate ◽  
Competitive Inhibitor ◽  
Dihydroxyacetone Phosphate ◽  
Carrier Protein ◽  
Sugar Phosphate ◽  
Wheat Endosperm ◽  
Single Carrier ◽  
Phosphate Translocator ◽  
Envelope Membranes ◽  
Hexose Phosphates

Amyloplasts were isolated and purified from wheat endosperm and the envelope membranes reconstituted into liposomes. Envelope membranes were solubilized in n-octyl β-D-glucopyranoside and mixed with liposomes supplemented with 5.6 mol% cholesterol to produce proteoliposomes of defined size, which showed negligible leakage of internal substrates. Transport experiments with proteoliposomes revealed a counter-exchange of glucose 1-phosphate (Glc1P), glucose 6-phosphate (Glc6P), inorganic phosphate (Pi), 3-phosphoglycerate and dihydroxyacetone phosphate. The Glc1P/Pi counter-exchange reaction exhibited an apparent Km for Glc1P of 0.4 mM. Glc6P was a competitive inhibitor of Glc1P transport (Ki 0.8 mM), and the two hexose phosphates could exchange with each other, indicating the operation of a single carrier protein. Glc1P/Pi antiport in proteoliposomes showed an exchange stoichiometry at pH 8.0 of 1 mol of phosphate transported per mol of sugar phosphate.

scholarly journals Analysis of carbohydrate transport across the envelope of isolated cauliflower-bud amyloplasts

1995 ◽  
Vol 307 (2) ◽  
pp. 521-526 ◽  
Author(s):  
T Möhlmann ◽  
O Batz ◽  
U Maass ◽  
H E Neuhaus
Keyword(s):  
Envelope Protein ◽  
Starch Synthesis ◽  
Specific Inhibitor ◽  
Competitive Inhibitor ◽  
Transport Proteins ◽  
Dihydroxyacetone Phosphate ◽  
Envelope Membrane ◽  
Phosphate Translocator ◽  
Low Concentrations ◽  
Carbohydrate Transport

Using isolated amyloplasts from cauliflower buds, we have characterized the interaction and transport of various carbohydrates across the envelope membrane of a heterotrophic plastid. According to our results, glucose 6-phosphate (Glc6P) and glucose 1-phosphate (Glc1P) do not share the same transport protein for uptake into cauliflower-bud amyloplasts. Glc6P-dependent starch synthesis is strongly inhibited in the presence of dihydroxyacetone phosphate (DHAP) or 4,4′-di-isothiocyano-2,2′- stilbenedisulphonic acid (DIDS), whereas Glc1P-dependent starch synthesis is hardly affected by these compounds. Analysis of the Glc6P uptake into proteoliposomes reconstituted from the envelope proteins of cauliflower-bud amyloplasts indicate that Glc6P is taken up in a counter-exchange mode with Pi, DHAP or Glc6P, whereas Glc1P does not act as a counter-exchange substrate. Pi is a strong competitive inhibitor of Glc6P uptake (Ki 0.8 mM) into proteoliposomes, whereas Glc1P does not significantly inhibit Glc6P transport. Beside a hexose-phosphate translocator, these amyloplasts possess an envelope protein mediating the transport of glucose across the membrane. This translocator exhibits an apparent Km for glucose of 2.2 mM and is inhibited by low concentrations of phloretin, known to be a specific inhibitor of glucose-transport proteins. Maltose inhibits the uptake of glucose (Ki 2.3 mM), indicating that both carbohydrates share the same translocator.

Nutritional and energy value of sweet pepper fruit depending on variety

2018 ◽  
Vol 6 (10) ◽  
pp. 150-158
Author(s):  
Viktor Koltunov ◽  
◽  
Kateryna Kalaida ◽  
Keyword(s):  
Sweet Pepper ◽  
Energy Value ◽  
Pepper Fruit

scholarly journals Sweet Pepper (Capsicum annuum L.) Fruits Contain an Atypical Peroxisomal Catalase That Is Modulated by Reactive Oxygen and Nitrogen Species

Antioxidants ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 374 ◽  
Author(s):  
Marta Rodríguez-Ruiz ◽  
Salvador González-Gordo ◽  
Amanda Cañas ◽  
María Jesús Campos ◽  
Alberto Paradela ◽  
...  
Keyword(s):  
Capsicum Annuum ◽  
Fruit Ripening ◽  
Reactive Oxygen ◽  
Bovine Liver ◽  
Sweet Pepper ◽  
Cysteine Residue ◽  
Nitrogen Species ◽  
Capsicum Annuum L ◽  
Native Molecular Mass ◽  
Pepper Fruit

During the ripening of sweet pepper (Capsicum annuum L.) fruits, in a genetically controlled scenario, enormous metabolic changes occur that affect the physiology of most cell compartments. Peroxisomal catalase gene expression decreases after pepper fruit ripening, while the enzyme is also susceptible to undergo post-translational modifications (nitration, S-nitrosation, and oxidation) promoted by reactive oxygen and nitrogen species (ROS/RNS). Unlike most plant catalases, the pepper fruit enzyme acts as a homodimer, with an atypical native molecular mass of 125 to 135 kDa and an isoelectric point of 7.4, which is higher than that of most plant catalases. These data suggest that ROS/RNS could be essential to modulate the role of catalase in maintaining basic cellular peroxisomal functions during pepper fruit ripening when nitro-oxidative stress occurs. Using catalase from bovine liver as a model and biotin-switch labeling, in-gel trypsin digestion, and nanoliquid chromatography coupled with mass spectrometry, it was found that Cys377 from the bovine enzyme could potentially undergo S-nitrosation. To our knowledge, this is the first report of a cysteine residue from catalase that can be post-translationally modified by S-nitrosation, which makes it especially important to find the target points where the enzyme can be modulated under either physiological or adverse conditions.

Mechanism of protein import across the chloroplast envelope

2000 ◽  
Vol 28 (4) ◽  
pp. 485-491 ◽  
Author(s):  
K. Chen ◽  
X. Chen ◽  
D. J. Schnell
Keyword(s):  
Protein Import ◽  
Essential Elements ◽  
Chloroplast Envelope ◽  
Envelope Membrane ◽  
Outer Envelope ◽  
Double Membrane ◽  
Protein Subunits ◽  
Targeting Signals ◽  
Outer Envelope Membrane ◽  
Envelope Membranes

The development and maintenance of chloroplasts relies on the contribution of protein subunits from both plastid and nuclear genomes. Most chloroplast proteins are encoded by nuclear genes and are post-translationally imported into the organelle across the double membrane of the chloroplast envelope. Protein import into the chloroplast consists of two essential elements: the specific recognition of the targeting signals (transit sequences) of cytoplasmic preproteins by receptors at the outer envelope membrane and the subsequent translocation of preproteins simultaneously across the double membrane of the envelope. These processes are mediated via the co-ordinate action of protein translocon complexes in the outer (Toe apparatus) and inner (Tic apparatus) envelope membranes.

scholarly journals Nitric oxide-dependent regulation of sweet pepper fruit ripening

2019 ◽  
Vol 70 (17) ◽  
pp. 4557-4570 ◽  
Author(s):  
Salvador González-Gordo ◽  
Rocío Bautista ◽  
M Gonzalo Claros ◽  
Amanda Cañas ◽  
José M Palma ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Fruit Ripening ◽  
Biochemical Analysis ◽  
Sweet Pepper ◽  
Supporting Evidence ◽  
Functional Categories ◽  
Fatty Acid Profiling ◽  
Pepper Fruit

Abstract Ripening is a complex physiological process that involves changes in reactive nitrogen and oxygen species that govern the shelf-life and quality of fruits. Nitric oxide (NO)-dependent changes in the sweet pepper fruit transcriptome were determined by treating fruits at the initial breaking point stage with NO gas. Fruits were also harvested at the immature (green) and ripe (red) stages. Fruit ripening in the absence of NO resulted in changes in the abundance of 8805 transcripts whose function could be identified. Among these, functional clusters associated with reactive oxygen/nitrogen species and lipid metabolism were significantly modified. NO treatment resulted in the differential expression of 498 genes framed within these functional categories. Biochemical analysis revealed that NO treatment resulted in changes in fatty acid profiling, glutathione and proline contents, and the extent of lipid peroxidation, as well as increases in the activity of ascorbate peroxidase and lipoxygenase. These data provide supporting evidence for the crucial role of NO in the ripening of pepper fruit.

Modeling of microwave assisted drying of osmotically pretreated red sweet pepper (Capsicum annum L.)

2012 ◽  
Vol 21 (4) ◽  
pp. 969-978 ◽  
Author(s):  
Sachidananda Swain ◽  
D. V. K. Samuel ◽  
Lalit M. Bal ◽  
Abhijit Kar ◽  
G. P. Sahoo
Keyword(s):  
Sweet Pepper ◽  
Microwave Assisted ◽  
Capsicum Annum
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