Model studies of the regulation of the Calvin photosynthesis cycle by cytosolic metabolites

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Abstract

A kinetic model for photosynthetic carbohydrate formation in the chloroplast of C3 plants is presented which includes consideration of the interaction of the phosphate translocator of the chloroplast envelope with external reactants such as 3-phosphoglycerate, dihydroxyacetone phosphate, and glyceraldehyde 3-phosphate in addition to inorganic (ortho)phosphate. The model is shown to account satisfactorily for experimentally observed effects of such reactants on the rates of carbon dioxide fixation and starch production in isolated chloroplast. The predictions of the model with regard to the regulation of stromal processes of photosynthetic carbohydrate formation by cytosolic concentration variables have been examined. The results indicate that the cytosolic concentrations of metabolites that interact with the phosphate translocator represent important regulatory signals. Increasing levels of exported photosynthetic (phosphoglycerates and triose phosphates) in the cytosol do not suppress the rate of photosynthetic carbon dioxide fixation, but redirects reaction flux such that starch production within the chloroplast is favoured at the expense of a decreased rate of photosynthate export to the cytosol.

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  • Chemical Process Engineering
Original languageEnglish
Pages (from-to)723-732
Number of pages10
JournalBiomedica Biochimica Acta
Volume49
Issue number8-9
StatePublished - 1990
Peer-reviewedYes