Ions channels/transporters and chloroplast regulation

• We describe the molecular nature of proteins involved in chloroplast ion import and homeostasis.
• We describe the role of ions on the assembly of the photosynthetic membranes network.
• We focus on the role of ion fluxes in the synthesis of ATP via their effect on the proton motive force.

Ions play fundamental roles in all living cells and their gradients are often essential to fuel transports, to regulate enzyme activities and to transduce energy within and between cells. Their homeostasis is therefore an essential component of the cell metabolism. Ions must be imported from the extracellular matrix to their final subcellular compartments. Among them, the chloroplast is a particularly interesting example because there, ions not only modulate enzyme activities, but also mediate ATP synthesis and actively participate in the building of the photosynthetic structures by promoting membrane-membrane interaction. In this review, we first provide a comprehensive view of the different machineries involved in ion trafficking and homeostasis in the chloroplast, and then discuss peculiar functions exerted by ions in the frame of photochemical conversion of absorbed light energy.

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