PerspectivePlant Science

Fine-Tuning Photosynthesis

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Science  04 Oct 2013:
Vol. 342, Issue 6154, pp. 50-51
DOI: 10.1126/science.1244943

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Summary

Most biochemical reactions in living cells are fueled by adenosine triphosphate (ATP) and/or the reducing agent reduced nicotinamide adenine dinucleotide phosphate (NADPH). In plant cells, these components are generated in mitochondria and chloroplasts through the respiratory and photosynthetic electron transfer chains. Nearly 50 years ago, Mitchell (1) proposed a unifying mechanism through which the respiratory and photosynthetic electron transfer reactions are coupled to proton pumping across the inner mitochondrial and thylakoid membranes; the thylakoid membranes are located within chloroplasts and contain the protein-pigment complexes that catalyze the primary reactions of photosynthesis (see the figure). This proton movement generates a transmembrane electrochemical gradient called the proton motive force. On page 114 of this issue, Carraretto et al. (2) show how a two-pore potassium channel helps to regulate the proton motive force.