Energy transfer and distribution in photosystem super/megacomplexes of plants.

Traditionally, two types of photosystem reaction centers (PSI and PSII) are thought to be spatially dispersed in the plant thylakoid membrane. In this model, PSI and PSII independently accept excitation energy from their own peripheral light-harvesting complexes, LHCI and LHCII, respectively, and form supercomplexes (PSI-LHCI and PSII-LHCII). However, recent studies using a combination of mild detergent treatment and spectroscopic analysis have revealed the existence of various megacomplexes such as a PSI-PSII megacomplex and a PSII megacomplex. Flexibility in the formation of supercomplexes and megacomplexes is important for land plants to regulate excitation energy to survive under strong and fluctuating sunlight on land.