Evidence for Inorganic Carbon Transport by Intact Chloroplasts of Chlamydomonas reinhardtii.

Isolated intact chloroplasts from wall-less mutants of Chlamydomonas reinhardtii accumulate inorganic carbon (C(i)) from the medium provided the cells had been adapted to low CO(2) photoautotrophic growth conditions. Chloroplasts from cultures grown on high (5%) CO(2) or photoheterotrophically with acetate did not accumulate inorganic carbon. Chloroplast C(i) accumulation from low CO(2) grown cells was light dependent and was inhibited by uncouplers and inhibitors of electron transport. In a model for C(i) accumulation by Chlamydomonas, it is proposed that CO(2) diffuses into the cell and C(i) accumulation occurs in the chloroplast.