ABSTRACT
ABSTRACT Photosynthetic electron transport in the thylakoid membrane is mediated by two photochemical reactions. In each photosystem, light-harvesting antenna complexes funnel the absorbed light energy into the core complex, resulting in charge separation in the reaction-centre chlorophyll. Because the amount of light energy absorbed oen exceeds the capacity of its utilization by CO2 xation, phototrophs have multiple mechanisms to regulate the eciency of light energy utilization. In light of recent progress in research there is a need to reconsider the commonly accepted view of their physiological function. Regulation of light-use eciency involves dynamic interactions between protein complexes in the thylakoid membrane. e evolutionary strategies for using each process to cope with the natural light environment have diverged between owering plants and green algae. ΔpH formed across the thylakoid membrane plays a critical role in regulating photosynthetic electron transport. In the photosystem II antenna, ΔpH regulates the photoprotective mechanism underlying non-photochemical quenching of chlorophyll uorescence. Cyclic electron transport around photosystem I regulates ΔpH formation, which is essential for photosystem I photoprotection. e supercomplexes including photosystem I are the machinery for this electron transport.
