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The presence of ribulose 1,5-biphosphate carboxylase oxigenase is required for the induction of the 37 Kda periplasmic carbonic anhydrase in Chlamydomonas reinhardtii
M. Plumed-Tavío, M. Jiménez del Río, G. García Reina and Z. Ramazanov

The effects of DCMU, acetate and temperature on the induction of the 37 kDa periplasmic carbonic anhydrase (37kDa pCA) in Chlamydomonas reinhardtii wild type and in a temperature sensitive mutant strain, designated 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 induction was repressed by DCMU, an inhibitor of photosynthesis. However, in the presence of acetate, DCMU did not prevent the induction of the 37 kDa pCA. For further identification of the signal of the CA induction, the effect of temperature on the induction of the 37 kDa pCA was studied in the wild type and in the temperature sensitive mutant strain. When grown at the permissive temperature (25°C) the mutant had a reduced level of Rubisco. Immunoblot analysis of the total cell homogenates against the 37 kDa pCA of Creinhardtii showed a cross-reaction with a 37 kDa polypeptide from low CO2 grown wild type and mutant cells, although the level of the signal was lower in mutant cells. At the nonpermissive temperature (35ºC), the level of Rubisco was not detectable by Western blot analysis and the cells required acetate 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 observed only in the wild type cells, but not in the mutant. We suggest that the presence of Rubisco is required for the induction of the 37 kDa pCA in C. reinhardtii.

Keywords: carbonic anhydrase, CO2 concentrating mechanism, photosynthesis, Rubisco. Abbreviations: CA, carbonic anhydrase; DCMU, 3-(3,4-dichlorophenyl)- 1,1-dimethylurea; DIC, dissolved inorganic carbon(CO2 + HC03-); RuBP, ribulose 1,5-biphosphate; Rubisco, ribulose 1,5-biphosphate carboxylase/oxygenase; CCM, carbon concentrating mechanism.
Contents of this volume Sci. Mar. 60(Suppl.1) : 149-154 Back PDF
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