THE PRESENCE OF RIBULOSE 1,5-BIPHOSPHATE CARBOXYLASE OXYGENASE IS REQUIRED FOR THE INDUCTION OF THE 37-KDA PERIPLASMIC CARBONIC-ANHYDRASE IN CHLAMYDOMONAS-REINHARDTII/

The effects of DCMU, acetate and temperature on the induction of the 3 7 kDa periplasmic carbonic anhydrase (37 kDa pCA) in Chlamydomonas rei nhardtii wild type and in a temperature sensitive mutant strain, desig nated as 68-4PP, were studied. Transfer of cells from high CO2 (5%, v/ v) to low CO2 (0.03%) provoked induction of the 37 kDa pCA and this in duction was repressed by DCMU, an inhibitor of photosynthesis. However , in the presence of acetate, DCMU did nor prevent the induction of th e 37 kDa pCA. For further identification of the signal of the CA induc tion, the effect of temperature on the induction of the 37 kDa pCA was studied in the wild type and in the temperature sensitive mutant stra in. When grown at the permissive temperature (25 degrees C) the mutant had a reduced level of Rubisco. Immunoblot analysis of the total cell homogenates against the 37 kDa pCA of C. reinhardtii showed a cross r eaction with a 37 kDa polypeptide from low CO2 grown wild type and mut ant cells, although the level of the signal was lower in mutant cells. At the nonpermissive remperature (35 degrees C), the level of Rubisco was not detectable by Western blot analysis and the cells required ac etate for growth. When cells were switched from high CO2 plus acetate to low CO2 plus acetate media, the induction of the 37 kDa pCA was obs erved only in the wild type cells, but not in the mutant. We suggest t hat the presence of Rubisco is required for the induction of the 37 kD a pCA in C. reinhardtii.