Induction of a high-CO2-inducible, periplasmic protein, H43, and its application as a high-CO2-responsive marker for study of the high-CO2-sensing mechanism in Chlamydomonas reinhardtii.

The unicellular green alga Chlamydomonas reinhardtii can acclimate to a broad range of environmental CO(2) concentrations. We observed that the cells synthesized a specific 43 kDa protein, H43, in the periplasmic space under photoautotrophic high-CO(2) conditions. Under low-CO(2) conditions, H43 disappeared.