A New Chloroplast Protein Is Induced by Growth on Low CO2 in Chlamydomonas reinhardtii

The biosynthesis of a 36 kilodalton polypeptide of Chlamydomonas reinhardtii was induced by photoautotrophic growth on low CO(2). Fractionation studies using the cell-wall-deficient strain of C. reinhardtii, CC-400, showed that this polypeptide was different from the low CO(2)-induced periplasmic carbonic anhydrase. In addition, the 36 kilodalton polypeptide was found to be localized in intact chloroplasts isolated from low CO(2)-adapting cultures. This protein may, in part, account for the different inorganic carbon uptake characteristics observed in chloroplasts isolated from high and low CO(2)-grown C. reinhardtii cells.