PsbS interacting proteins - PsbS interactions involved in the activation of energy dissipation in Arabidopsis

PsbS Protein Interactions during Non-photochemical quenching The non-photochemical quenching of excitation energy (NPQ) describes a photoprotective mechanism in the antenna of PSII which dissipates excess excitation energy as heat at the level of 1Chl* and by that prevents the formation of singlet oxygen in PSII. Four different components contribute to NPQ, namely qT, qE, qZ and qI. Under saturating light conditions, the qE represents the dominant NPQ component; qE is based on a complex mechanism which strictly depends on the ΔpH across the thylakoid membrane, the PsbS protein and the xanthophyll zeaxanthin (Zx). The central role of PsbS in these processes is related to the function of PsbS as sensor of the lumen pH. However, the molecular basis of this central function and particularly the underlying interactions of PsbS with PSII antenna proteins that lead to energy quenching are largely unclear. In this work, we present an in vitro approach to identify protein transient interactions involving the PsbS protein during NPQ induction and relaxation in Arabidopsis thaliana, revealing its direct role in the formation of quenching sites in the antenna complexes of photosystem II.