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.
The Role of External Carbonic Anhydrase in Inorganic Carbon Acquisition by Chlamydomonas reinhardii at Alkaline pH
