The effects of pH and dissolved inorganic carbon on external carbonic anhydrase activity in Chlorella saccharophila

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.

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Construction and analysis of a high-CO2-requiring mutant of the cyanobacterium Anabaena sp. strain PCC7120

Functional Plant Biology ◽

10.1071/pp99186 ◽

2000 ◽

Vol 27 (11) ◽

pp. 1077

Author(s):

Wu Tianfu ◽

Song Lirong ◽

Liu Yongding

Keyword(s):

Carbonic Anhydrase ◽

Culture Medium ◽

Dissolved Inorganic Carbon ◽

Carbonic Anhydrase Activity ◽

Filamentous Cyanobacterium ◽

High Co2 ◽

Cyanobacterium Anabaena ◽

Anabaena Sp ◽

Inefficient Operation ◽

Mutant Cells

A mutant of Anabaena sp. strain PCC7120 requiring high CO2 was generated using Tn5 mutagenesis. This is the first data for a filamentous cyanobacterium. The mutant was capable of growing at 5% CO2, but incapable of growing at air levels of CO2. Southern hybridization analysis indicated that the Anabaena genome was inserted by the transposon at one site. The apparent photosynthetic affinity of the mutant to external dissolved inorganic carbon (DIC) was about 300 times lower that of the wild type (WT), and the medium alkalization rate as well as the carboxysomal carbonic anhydrase activity of the mutant was also lower than those of the WT. When the mutant was transferred from the culture medium bubbled with 5% CO2 to higher DIC (8.4% CO2) or 1% CO2, it showed similar responses to the WT. However, aberrant carboxysomes were found in the mutant cells through ultrastructural analysis, indicating it was most probably the wrong organization of the carboxysomes that eventually led to the inefficient operation of carboxysomal carbonic anhydrase and the subsequent defectiveness of the mutant in utilizing DIC.

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INORGANIC CARBON LIMITATION, EXOFACIAL CARBONIC ANHYDRASE ACTIVITY, AND PLASMA MEMBRANE REDOX ACTIVITY IN MARINE PHYTOPLANKTON SPECIES

Journal of Phycology ◽

10.1046/j.1529-8817.1999.3561200.x ◽

1999 ◽

Vol 35 (6) ◽

pp. 1200-1205 ◽

Cited By ~ 19

Author(s):

Nabil A. Nimer ◽

Miao Xiao Ling ◽

Colin Brownlee ◽

Michael J. Merrett

Keyword(s):

Plasma Membrane ◽

Carbonic Anhydrase ◽

Inorganic Carbon ◽

Carbonic Anhydrase Activity ◽

Marine Phytoplankton ◽

Redox Activity ◽

Carbon Limitation ◽

Phytoplankton Species ◽

Plasma Membrane Redox ◽

Inorganic Carbon Limitation

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Carbonic anhydrase activity and inorganic carbon fluxes in low- and high-C1 cells of Chlamydomonas reinhardtu and Scenedesmus obliquus

Physiologia Plantarum ◽

10.1111/j.1399-3054.1994.tb08812.x ◽

1994 ◽

Vol 90 (3) ◽

pp. 537-547 ◽

Cited By ~ 47

Author(s):

Kristin Palmqvist ◽

Jian-Wei Yu ◽

Murray R. Badger

Keyword(s):

Carbonic Anhydrase ◽

Inorganic Carbon ◽

Scenedesmus Obliquus ◽

Carbon Fluxes ◽

Carbonic Anhydrase Activity

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

Canadian Journal of Botany ◽

10.1139/b91-141 ◽

1991 ◽

Vol 69 (5) ◽

pp. 1103-1108 ◽

Cited By ~ 3

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.

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Effects of pH on cell morphology and carbonic anhydrase activity and localization in bloom-forming Mougeotia (Chlorophyta, Charophyceae)

Canadian Journal of Botany ◽

10.1139/cjb-78-9-1206 ◽

2000 ◽

Vol 78 (9) ◽

pp. 1206-1214 ◽

Cited By ~ 1

Author(s):

Patricia Arancibia-Avila ◽

John R. Coleman ◽

William A. Russin ◽

Lee W. Wilcox ◽

James M. Graham ◽

...

Keyword(s):

Carbonic Anhydrase ◽

Cell Morphology ◽

Carbonic Anhydrase Activity ◽

Effects Of Ph

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A physiological evaluation of carbon sources for calcification in the octocoral Leptogorgia virgulata (Lamarck).

Journal of Experimental Biology ◽

10.1242/jeb.200.20.2653 ◽

1997 ◽

Vol 200 (20) ◽

pp. 2653-2662

Author(s):

J M Lucas ◽

L W Knapp

Keyword(s):

Calcium Carbonate ◽

Carbonic Anhydrase ◽

Inorganic Carbon ◽

Sea Water ◽

Dissolved Inorganic Carbon ◽

Carbon Sources ◽

Iodoacetic Acid ◽

Transport Systems ◽

Disulfonic Acid ◽

Leptogorgia Virgulata

The union of calcium cations with carbonate anions to form calcium carbonate (CaCO3) is a fundamentally important physiological process of many marine invertebrates, in particular the corals. In an effort to understand the sources and processes of carbon uptake and subsequent deposition as calcium carbonate, a series of studies of the incorporation of 14C-labeled compounds into spicules was undertaken using the soft coral Leptogorgia virgulata. It has been surmised for some time that dissolved inorganic carbon in sea water is used in the biomineralization process. Furthermore, it was suspected that metabolically generated CO2 is also available for calcification. As a means of testing these possible sources of carbon in spicule calcification, key enzymes or transport systems in each pathway were inhibited. First, the enzyme carbonic anhydrase was specifically inhibited using acetazolamide. Second, the active transport of bicarbonate was inhibited using DIDS (4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid). Third, CO2 generation resulting from glycolysis and the citric acid cycle was arrested using iodoacetic acid, which interferes specifically with the enzyme glyceraldehyde-3-phosphate dehydrogenase. The results indicate that dissolved CO2 is the largest source of carbon used in the formation of calcitic sclerites, followed by HCO3- from dissolved inorganic carbon. In L. virgulata, the dissolved inorganic carbon is responsible for approximately 67% of the carbon in the sclerites. The other 33% comes from CO2 generated by glycolysis. Two important conclusions can be drawn from this work. First, carbon for spiculogenesis comes not only from dissolved inorganic carbon in the environment but also from metabolically produced carbon dioxide. While the latter has been theorized, it has never before been demonstrated in octocorals. Second, regardless of the carbon source, the enzyme carbonic anhydrase plays a pivotal role in the physiology of spicule formation in Leptogorgia virgulata.

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Inorganic carbon transport in some marine microalgal species

Canadian Journal of Botany ◽

10.1139/b91-133 ◽

1991 ◽

Vol 69 (5) ◽

pp. 1032-1039 ◽

Cited By ~ 20

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.

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