Photsynthesis and low CO2 inducible protein synthesis in a newly isolated high CO2-preferring mutant of Chlamydomonas reinhardtii
J.R. Betancort Rodríguez, J.J. Santana Rodríguez, G. García Reina and Z. Ramazanov

The effect of external CO2 concentrations on the protein synthesis in Chlamydomonas reinhardtii wild-type is compared with that of a new high CO2-preferring mutant, designated as pyr-45. Radiolabeled wild-type and pyr-45 cells exhibit up-regulation of two polypeptides (42-45kDa) when adapted from high (5%CO2 in air) to low CO2 (0.03%), and wild-type induces three new ones (21, 36 37 kDa), but pyr-45 induces no new polypeptides. Total proteins from pyr-45 mutant cells do not crossreact with antibodies against the three low CO2-inducible polypeptides of wild-type. The CO2 requirement for half maximal rates of photosynthesis decreases when pyr-45 cells are switched from high to low CO2, but not to the extent of wild-type cells. When exogenous carbonic anhydrase (CA) is added to these partially adapted cells,the CO2 requirement is further reduced, but still not completely. The up-regulation of the 42-45kDa polypeptides under low CO2 growth conditions suggests these changes play a role in the adaptation of algal cells to limiting CO2 concentrations in the environment and in the function of the CO2 concentrating mechanism (CCM) in Chlamydomonas reinhardtii.

Keywords: Adaptation, carbonicanhydrase, Chlamydomonas, CO2,-concentrating mechanism, mutant, photosynthesis, protein synthesis.
Contents of this volume Sci. Mar. 60(Suppl.1) : 135-140 Back PDF
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