Abstract
It has been established that a green alga, Chlamydomonas reinhardtii, induces carbon-concentrating mechanism (CCM) and accumulates inorganic carbon under CO2 limiting condition. However, the driving mechanism of CO2-uptake systems remains unclear so far. We characterized the effects of several kinds of photosynthetic inhibitors on CO2-uptake activity in wild type cells. Both O2 evolving activity (H2O to NaHCO3) and CO2-uptake activity were inhibited to 50% of original levels in the presence of 0.2 μM DCMU and the inhibitory effect of DCMU on both activities showed good fit to Michaelis-Menten equation, suggesting that light-induced CO2-uptake is directly driven by photosynthetic electron transport. Now we characterize the property of CO2-uptake in some photosynthetic and respiratory mutants to address the sites of photosynthetic electron flow that contributes considerably to the light-dependent CO2-uptake of Chlamydomonas.
