Ed. Demidov, ACTIVATION OF THE CYCLIC PHOTOPHOSPHORYLATION DURING THE INDUCTION OFTHE CO2-CONCENTRATING MECHANISM IN CHLAMYDOMONAS-REINHARDTII CELLS, Russian journal of plant physiology, 41(2), 1994, pp. 166-171
Photophosphorylation in Chlamydomonas reinhardtii (mutant cw-92 devoid
of cell walls) was studied in order to clarify the involvement of cyc
lic photophosphorylation in the mechanism of CO2 concentration. Cells
transfer from high (2 - 5%) to low (0.03%) CO2 concentrations, in addi
tion to increasing cell affinity for CO2, reversibly inactivated PS II
and the V(max). In response to the decrease in CO2 concentration, a 2
- to 3-fold increase in the cyclic photophosphorylation rate was obser
ved. A conclusion was drawn that the ATP energy of cyclic phosphorylat
ion might sustain the active transport of CO2 against the concentratio
n gradient during the induction of the CO2-concentrating mechanism. Th
e phenomenon of energy storage surpassing the rate calculated upon O2-
gas exchange previously reported for Chlorella cells is also anticipat
ed to be a manifestation of energy of the intracellular CO2-Concentrat
ing mechanism.