S. M. Kochubei, O. O. Stasik, and O. I. Volovik
Institute of Plant Physiology and Genetics, National Academy of Sciences of Ukraine,
ul. Vasil’kovskaya 31/17, Kiev, 252022 Ukraine
Received May 29, 1995
Abstract—The effect of membrane protein phosphorylation on the excitation spectra of the long-wavelength
fluorescence of isolated chloroplasts was investigated in two maize inbreds. These fluorescence data are com-
pared with the effects of protein phosphorylation on the rates of cyclic and noncyclic electron transfer within
PSI, the rates of CO2 assimilation, and the composition of the products of dark photosynthetic processes. Phos-
phoproteins were shown to selectively interact with two antenna complexes of PS I (F720 and F735), the char-
acter of the interaction varying between the two maize lines. The cyclic and noncyclic electron transfer in PS I
were shown to be differentially activated by the protein phosphorylation. This activation was due to an
enhanced excitation energy transfer caused by a selective binding of phosphoproteins to the antenna complexes
F720 and F735. CO2 fixation rates and the patterns of 14C-labeling of photosynthates differed between the two
maize lines. It is concluded that, as shown previously in pea chloroplasts, selective interaction of phosphopro-
teins with two different antennae of PS I in maize chloroplasts results in a differential enhancement of cyclic
and noncyclic electron flows. Products of dark photosynthetic carbon metabolism differed in the two maize
lines, in which cyclic and noncyclic electron transfer were differentially activated upon membrane protein phos-
phorylation.
Key words: regulation of photosynthesis - phosphoproteins - chloroplasts - fluorescence - electron transport -
carbon metabolism
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