Plant Science

Regulating Supply and Demand

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Science  05 Feb 2010:
Vol. 327, Issue 5966, pp. 625
DOI: 10.1126/science.327.5966.625-a
CREDIT: N. KEVITIYAGALA/SCIENCE

Photosynthesis, the means by which green plants use sunlight to convert CO2 into sugars, depends on the harvesting of photons and their delivery to two photosystem complexes (I and II). When light intensity or spectral composition varies, electron flow through the photosystems can be modulated in what is known as transitions of state. The association of light-harvesting protein complexes (LHCs) with the photosystems is regulated by phosphorylation and dephosphorylation of the LHC so as to maximize photosynthetic efficiency.

In Arabidopsis, the protein kinase responsible for phosphorylation of this complex is STN7. Pribil et al. have characterized the thylakoid-associated phosphatase TAP38 and show that TAP38-deficient plants accumulated phosphorylated LHCs, whereas TAP38 overexpression mimicked a loss-of-function mutation in the kinase STN7. These data suggest that TAP38 controls the dephosphorylation of the LHC and offer a means by which it might be possible to engineer more efficient photosynthetic systems.

PLoS Biol. 8, e1000288 (2010).

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