The PsbS protein plays important roles in photosystem II supercomplex remodeling under elevated light conditions

Leaves from three different Arabidopsis lines with different expression levels of PsbS protein showed different levels of non-photochemical quenching. The PsbS deficient plant npq4 showed remarkable reduction of electron transport rate, while the other two lines with a moderate amount (wild type) or an overexpression of PsbS (L17) presented unchanged electron transport rates under the same range of high light intensities. Biochemical investigation revealed that the plant with the highest PsbS content (L17) sustained the highest level of stable PSII-LHCII supercomplex structure, and displayed the smallest fluorescence quenching in the thylakoid membranes, the most efficient linear electron transport and the smallest cyclic electron transport. Based on these observations, it is proposed that the remodeling of PSII-LHCII supercomplexes affected by PsbS plays important roles in regulating the energy balance in thylakoid membrane and in ensuring the sophisticated coordination between energy excitation and dissipation.