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.

The role of the chloroplast in inorganic carbon acquisition by Chlamydomonas reinhardtii

1991 ◽  
Vol 69 (5) ◽  
pp. 1017-1024 ◽  
Author(s):  
James V. Moroney ◽  
Catherine B. Mason
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Inorganic Carbon ◽  
Published Data ◽  
Carbon Uptake ◽  
Intact Chloroplasts ◽  
Inorganic Carbon Transport ◽  
Inorganic Carbon Uptake ◽  
Carbon Transport ◽  
Inorganic Carbon Acquisition

The role of the chloroplast in algal inorganic carbon acquisition is reviewed. Unicellular green algae possess the ability to grow photoautotrophically at very low CO2 concentrations. The presence of a CO2-concentrating system that elevates the CO2 level within the cell can account for the algae's ability to reduce photorespiration and grow under these conditions. The mechanism of this inorganic carbon transport is unclear at present, although both the plasmalemma and the chloroplast have been implicated in this process. Three aspects of the role of the chloroplast in Chlamydomonas reinhardtii inorganic carbon uptake are discussed in this review. First, the present models of inorganic carbon uptake are summarized. Second, the purity and integrity of intact chloroplast preparations are discussed. Third, an evaluation of the published data on inorganic carbon uptake by isolated intact chloroplasts is presented. Key words: Chlamydomonas reinhardtii, carbonic anhydrase, chloroplast, active CO2 uptake.

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.

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