Adaptation of Chlamydomonas reinhardtii High CO2-Requiring Mutants to Limiting CO2
Chlamydomonas reinhardtii and other unicellular green algae use an energy-requiring, CO2-concentrating system, inducible by limiting inorganic carbon (Ci) concentrations, to increase intracellular CO2 concentrations (1). Operation of the CO2-concentrating system results in a high affinity for Ci in photosynthesis. Increased intracellular CO2 also reduces photorespiration and O2 inhibition of photosynthesis by competitive inhibition of RuBP oxygenase. The CO2-concentrating system involves active transport of Ci and includes CA as a component. This system apparently is only fully functional when cells adapt to low CO2 (air-adapted cells), since cells exhibit much lower affinity for Ci when grown at 5% CO2 (CO2-enriched cells).
KeywordsUnicellular Green Alga C02R Mutant Defective Component C02R Strain Soluble Polypeptide
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