Structure, regulation and assembly of the photosynthetic electron transport chain

Abstract

The electron transfer chain of chloroplast thylakoid membranes uses solar energy to split water into electrons and protons, creating energetic gradients that drive the formation of photosynthetic fuel in the form of NADPH and ATP. These metabolites are then used to power the fixation of carbon dioxide into biomass through the Calvin–Benson–Bassham cycle in the chloroplast stroma. Recent advances in molecular genetics, structural biology and spectroscopy have provided an unprecedented understanding of the molecular events involved in photosynthetic electron transfer from photon capture to ATP production. Specifically, we have gained insights into the assembly of the photosynthetic complexes into larger supercomplexes, thylakoid membrane organization and the mechanisms underpinning efficient light harvesting, photoprotection and oxygen evolution. In this Review, I focus on the angiosperm plant thylakoid system, outlining our current knowledge on the structure, function, regulation and assembly of each component of the photosynthetic chain. I explain how solar energy is harvested and converted into chemical energy by the photosynthetic electron transfer chain, how its components are integrated into a complex membrane macrostructure and how this organization contributes to regulation and photoprotection. The electron transfer chain in chloroplast thylakoid membranes uses solar energy to produce NADPH and ATP, which power carbon fixation into biomass. This Review discusses the structure and function of the core photosynthesis complexes and provides recent insights into their regulation and assembly.