scholarly journals Carbonic Anhydrase Activity in Isolated Chloroplasts of Wild-Type and High-CO2-Dependent Mutants of Chlamydomonas reinhardtii as Studied by a New Assay

1994 ◽  
Vol 105 (4) ◽  
pp. 1197-1202 ◽  
Author(s):  
G. L. Katzman ◽  
S. J. Carlson ◽  
Y. Marcus ◽  
J. V. Moroney ◽  
R. K. Togasaki
Keyword(s):  
Carbonic Anhydrase ◽  
Chlamydomonas Reinhardtii ◽  
Carbonic Anhydrase Activity ◽  
Wild Type ◽  
High Co2 ◽  
Isolated Chloroplasts

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

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.

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.

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.

scholarly journals Cycling of the signaling protein phospholipase D through cilia requires the BBSome only for the export phase

2013 ◽  
Vol 201 (2) ◽  
pp. 249-261 ◽  
Author(s):  
Karl F. Lechtreck ◽  
Jason M. Brown ◽  
Julio L. Sampaio ◽  
Julie M. Craft ◽  
Andrej Shevchenko ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Chlamydomonas Reinhardtii ◽  
Phospholipase D ◽  
Lipid Composition ◽  
Intraflagellar Transport ◽  
Secondary Effect ◽  
Wild Type ◽  
Signaling Protein ◽  
Over Time ◽  
Dependent Mechanism

The BBSome is a complex of seven proteins, including BBS4, that is cycled through cilia by intraflagellar transport (IFT). Previous work has shown that the membrane-associated signaling protein phospholipase D (PLD) accumulates abnormally in cilia of Chlamydomonas reinhardtii bbs mutants. Here we show that PLD is a component of wild-type cilia but is enriched ∼150-fold in bbs4 cilia; this accumulation occurs progressively over time and results in altered ciliary lipid composition. When wild-type BBSomes were introduced into bbs cells, PLD was rapidly removed from the mutant cilia, indicating the presence of an efficient BBSome-dependent mechanism for exporting ciliary PLD. This export requires retrograde IFT. Importantly, entry of PLD into cilia is BBSome and IFT independent. Therefore, the BBSome is required only for the export phase of a process that continuously cycles PLD through cilia. Another protein, carbonic anhydrase 6, is initially imported normally into bbs4 cilia but lost with time, suggesting that its loss is a secondary effect of BBSome deficiency.

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