The localization of active inorganic carbon transport at the plasma membrane in Chlorella ellipsoidea

1991 ◽  
Vol 69 (5) ◽  
pp. 1025-1031 ◽  
Author(s):  
Caterina Rotatore ◽  
Brian Colman
Keyword(s):  
Mass Spectrometry ◽  
Plasma Membrane ◽  
Carbonic Anhydrase ◽  
Inorganic Carbon ◽  
Carbonic Anhydrase Activity ◽  
Bicarbonate Transport ◽  
Chlorella Ellipsoidea ◽  
Intact Cells ◽  
Whole Cells ◽  
Isolated Chloroplasts

A study has been made of the capacity of whole cells and intact, photosynthetically active, isolated chloroplasts of Chlorella ellipsoidea (UTEX 20) to take up CO2 by active transport. Assays for carbonic anhydrase activity and the monitoring of CO2 uptake by cells and chloroplasts was carried out by mass spectrometry. No external carbonic anhydrase was detected in whole cells or on the outer surface of the isolated chloroplasts. Upon illumination, whole cells rapidly depleted CO2 from the medium to a level below the equilibrium CO2 concentration before maximum photosynthetic O2 evolution rates were established. Addition of bovine carbonic anhydrase resulted in the reestablishment of equilibrium CO2 concentrations, indicating that the cells were actively and selectively depleting the medium of CO2. This CO2 uptake was inhibited by 10 μM diethylstilbestrol. No such rapid depletion of CO2 was observed with isolated intact chloroplasts, although the organelles demonstrated rates of photosynthetic O2 evolution of about 60% of the parent cells. Photosynthetic rates of chloroplast suspensions exceeded the rate of CO2 supply only twofold, indicating that chloroplasts have a limited ability for HCO3− uptake. Intact cells, however, use HCO3− readily. These results indicate that the principal location of inorganic carbon transporters, both for CO2 and HCO3−, is at the plasma membrane in this alga. Key words: Chlorella ellipsoidea, CO2 transport, bicarbonate transport, chloroplasts, mass spectrometry, carbonic anhydrase.

Inorganic carbon transport in some marine microalgal species

1991 ◽  
Vol 69 (5) ◽  
pp. 1032-1039 ◽  
Author(s):  
M. J. Merrett
Keyword(s):  
Carbonic Anhydrase ◽  
Inorganic Carbon ◽  
Silicone Oil ◽  
Ph Regulation ◽  
Carbonic Anhydrase Activity ◽  
Carbon Accumulation ◽  
Bicarbonate Transport ◽  
High Affinity ◽  
Inorganic Carbon Transport ◽  
Carbon Transport

Inorganic carbon transport was investigated in a range of marine microalgae. A small-celled strain of Stichococcus bacillaris, containing appreciable carbonic anhydrase activity, showed a high affinity for CO2, while measurement of the internal inorganic carbon pool by the silicone oil layer centrifugal filtering technique showed cells concentrated inorganic carbon up to 20-fold in relation to the external medium at pH 5.0 but not pH 8.3. The addition of 14CO2 or H14CO3− to cells in short-term kinetic experiments at pH 8.3 confirmed that only CO2 provides the exogenous substrate for substantial inorganic carbon accumulation within the cell. High-affinity HCO3− transport in Phaeodactylum tricornutum and Porphyridium purpureum is dependent on sodium ions, while intracellular carbonic anhydrase increased the steady-state flux of CO2 from inside the plasmalemma to Rubisco. In the presence of HCO3− the intracellular pH in cells of P. purpureum is 7.1 but on carbon starvation the pH falls to 6.0. Ethoxyzolamide blocks bicarbonate-dependent alkalinization of the cytosol, confirming a central role for carbonic anhydrase–bicarbonate in cytosolic pH regulation. Carbonic anhydrase activity is pH dependent in P. purpureum so synergistic interaction between CO2 uptake and bicarbonate transport may occur.

Localization of carbonic anhydrase on pulmonary artery endothelial cells in culture

1982 ◽  
Vol 53 (4) ◽  
pp. 914-919 ◽  
Author(s):  
U. S. Ryan ◽  
P. L. Whitney ◽  
J. W. Ryan
Keyword(s):  
Endothelial Cells ◽  
Plasma Membrane ◽  
Carbonic Anhydrase ◽  
Pulmonary Artery ◽  
Venous Blood ◽  
Carbonic Anhydrase Activity ◽  
Intact Cells ◽  
Cells In Culture ◽  
Carbonic Anhydrase B ◽  
Arterial Blood

Bovine pulmonary artery endothelial cells in culture possess carbonic anhydrase activity and immunoreactivity. The intact cells and cell homogenates lower the pH of 25 mM triethanolamine sulfate buffer saturated with CO2 (starting pH 8.1). The intact cells are more reactive than the cell homogenates, and the enzymic activity is enriched in association with the plasma membrane fraction. Specific immunofluorescence is obtained when the cells are incubated with rabbit antibovine erythrocyte carbonic anhydrase B and then with goat antirabbit immunoglobulin G coupled to fluorescein. At the level of electron microscopy, antibodies to carbonic anhydrase B are reactive with sites along the plasma membrane and associated caveolae. Multivesicular bodies are the only intracellular sites labeled and appear to correspond to the globular sites of intracellular immunofluorescence. Cells maintained and propagated in culture in the absence of an exogenous source of carbonic anhydrase nonetheless possess carbonic anhydrase activity, suggesting that the cells are capable of synthesizing the enzyme. Taken together, our results indicate that pulmonary artery endothelial cells possess carbonic anhydrase situated so that the enzyme could readily catalyze the dehydration of plasma HCO-3 to facilitate CO2 excretion and participate in the regulation of blood pH as central venous blood is converted into systemic arterial blood.

Fractionation of carbonic anhydrase activity in Gracilaria sp. (Rhodophyta) and Enteromorpha intestinalis (Chlorophyta): changes in the extracellular activity in response to inorganic carbon levels

2000 ◽  
Vol 27 (12) ◽  
pp. 1161 ◽  
Author(s):  
Jesús R. Andría ◽  
Juan J. Vergara ◽  
J. Lucas Pérez-Lloréns
Keyword(s):  
Carbonic Anhydrase ◽  
Inorganic Carbon ◽  
Soluble Fraction ◽  
Total Activity ◽  
Carbonic Anhydrase Activity ◽  
Enteromorpha Intestinalis ◽  
Short Term ◽  
Carbon Availability ◽  
Species Specific ◽  
Extracellular Activity

The presence of different carbonic anhydrase (EC 4.2.1.1) activities has been investigated in the intertidal macroalgae Gracilaria sp. and Enteromorpha intestinalis (L.) Nees by using fractionation techniques. Activities, measured potentiometrically, were recorded for all fractions in both species, including those containing proteins associated with chloroplast membranes. In Gracilaria sp., most of the total activity was present in the soluble fraction, while similar activities were obtained for all fractions in E. intestinalis. By using inhibitors with a different capacity to enter the cell (acetazolamide and 6-ethoxyzolamide, inhibitors of external and total activity, respectively), a surface-accessible location was indicated for a high proportion of the soluble activity obtained in Gracilaria sp. In E. intestinalis, the inhibitor assays showed a substantial dependence of photosynthesis on intracellular activity. The short-term regulation of the extracellular activity in response to inorganic carbon availability was also examined in both macroalgae. Rapid repression (after 2 h) of the activity was recorded when Gracilaria sp. was transferred from limited to replete carbon conditions, while a fairly constant activity was recorded for E. intestinalis. In contrast, an increase of external activity was obtained for both macroalgae after being transferred to carbon-limited conditions, this response being more pronounced in E. intestinalis. Our results suggest the occurrence of a species-specific carbonic anhydrase system.

Plasma membrane-bound carbonic anhydrase activity in the regenerating rat liver

1991 ◽  
Vol 1061 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Jose Juan García Marín ◽  
Arancha Tabernero Urbieta ◽  
Fernando Pérez Barriocanal ◽  
Emilio Rodríguez Barbero ◽  
Nelida Eleno
Keyword(s):  
Plasma Membrane ◽  
Carbonic Anhydrase ◽  
Rat Liver ◽  
Carbonic Anhydrase Activity ◽  
Regenerating Rat Liver ◽  
Membrane Bound

Studies on the carbonic anhydrase activity in Synechocystis PCC6803 wild type and an acetazolamide-resistant mutant

1991 ◽  
Vol 69 (5) ◽  
pp. 1103-1108 ◽  
Author(s):  
S. Bedu ◽  
F. Joset
Keyword(s):  
Carbonic Anhydrase ◽  
Inorganic Carbon ◽  
Physiological Role ◽  
Resistant Mutant ◽  
Carbonic Anhydrase Activity ◽  
Wild Type ◽  
Synechocystis Pcc6803 ◽  
Physiological Analysis ◽  
Carbon Concentrations

The problem of the role and the localization of carbonic anhydrase activity in cyanobacteria has been addressed by two approaches using strain Synechocystis PCC6803. Physiological analysis of the differential effects of carbonic anhydrase inhibitors on the entry and accumulation of CO2 in cells grown under low or high inorganic carbon concentrations and determination of carbonic anhydrase activities in cellular subfractions led to the hypothesis of the presence of two different enzymes in this strain. This conclusion is compatible with current models. Only the internal enzyme could be regulated by variations of the external inorganic carbon concentrations. A parallel analysis of a mutant of this strain resistant to the inhibitor acetazolamide supported the hypothesis of the presence of two enzymes. This clone would be selectively impaired in the carbonic anhydrase activity involved in the maintenance of the internal CO2 pool, while its transport capacity is unchanged. Key words: carbonic anhydrase, physiological role, localization, inhibitors, cyanobacteria, mutant.

Extracellular carbonic anhydrase of Chlamydomonas reinhardtii: localization, structural properties, and catalytic properties

1991 ◽  
Vol 69 (5) ◽  
pp. 1079-1087 ◽  
Author(s):  
H. David Husic
Keyword(s):  
Plasma Membrane ◽  
Carbonic Anhydrase ◽  
Chlamydomonas Reinhardtii ◽  
Inorganic Carbon ◽  
Catalytic Properties ◽  
Physiological Role ◽  
Carbon Utilization ◽  
Unicellular Green Alga ◽  
Inorganic Carbon Utilization ◽  
Inorganic Carbon Acquisition

In the unicellular green alga Chlamydomonas reinhardtii, a form of the enzyme carbonic anhydrase that is localized outside of the plasma membrane is an inducible component of a system that is involved in inorganic carbon acquisition and concentration from the growth medium. This article contains a review and analysis of the current literature regarding the extracellular carbonic anhydrase from Chlamydomonas reinhardtii and presents some new studies on its extracellular localization, physiological role in inorganic carbon acquisition, and some of the structural and catalytic properties of the enzyme. Key words: carbonic anhydrase, Chlamydomonas reinhardtii, inorganic carbon utilization.

Involvement of Plasmalemmasomes and Carbonic Anhydrase in Photosynthetic Utilization of Bicarbonate in Chara corallina

1985 ◽  
Vol 12 (3) ◽  
pp. 241 ◽  
Author(s):  
G.D Price ◽  
M.R Badger ◽  
M.E Bassett ◽  
M.I Whitecross
Keyword(s):  
Carbonic Anhydrase ◽  
Inorganic Carbon ◽  
High Growth ◽  
Chara Corallina ◽  
Alkaline Media ◽  
O2 Evolution ◽  
Intact Cells ◽  
The Media ◽  
Culture Development ◽  
Inorganic Carbon Concentration

There is a clear relationship between the density of plasmalemmasomes (PLSs) in the acid band regions of whorl cells of Chara corallina and the capacity of these cells to utilize HCO*�/3 for photosynthesis. For cells grown in alkaline media, high PLS densities on the plasmalemma (50-85% coverage) were always correlated with high rates of HCO*�/3 dependent O2 evolution (pH 9.3), reaching rates of 17-23 mol O2 mg Chl-� h-� at 5 mM inorganic carbon concentration. In alkaline culture, development of high PLS densities and high rates of HCO*�/3 usage were related to provision of limiting levels of CO2 (< 12 M) in the media. High growth levels of CO2 (267 M) markedly reduced PLS densities and rates of HCO*�/3 usage. Bicarbonate dependent O2 evolution (pH 9.3) was extremely sensitive to the carbonic anhydrase inhibitor ethoxyzolamide (20 M), whilst CO2-dependent O2 evolution (pH 5.5) was insensitive. Carbonic anhydrase (CA) activity was present in homogenates and in intact cells, suggesting that a periplasmic location is possible. It seems reasonable to suggest that, for Chara corallina, high PLS densities and CA activity are required for efficient utilization of HCO*�/3 at alkaline pH. Plasmalemmasomes may be part of the HCO*�/3-utilizing mechanism by acting as sites for localized pH generation, thus facilitating HCO*�/3 utilization by either H+/HCO*�/3 active cotransport or CA and pH-mediated external conversion of HCO*�/3 to CO2 in the periplast.

Sign in / Sign up

Export Citation Format

Share Document