Interaction between the photoprotective protein LHCSR3 and C 2 S 2 Photosystem II supercomplex in Chlamydomonas reinhardtii

• Published in: Biochimica et biophysica acta. Bioenergetics Vol. 1858; no. 5; pp. 379 - 385
• Main Authors: Semchonok, Dmitriy A, Sathish Yadav, K N, Xu, Pengqi, Drop, Bartlomiej, Croce, Roberta, Boekema, Egbert J
• Format: Journal Article
• Language: English
• Published: Netherlands 01.05.2017
• Subjects: Binding Sites; Chlamydomonas reinhardtii - genetics; Chlamydomonas reinhardtii - metabolism; Chlamydomonas reinhardtii - ultrastructure; Energy Transfer; Light; Light-Harvesting Protein Complexes - chemistry; Light-Harvesting Protein Complexes - genetics; Light-Harvesting Protein Complexes - metabolism; Light-Harvesting Protein Complexes - ultrastructure; Microscopy, Electron - methods; Photosynthesis; Photosystem II Protein Complex - chemistry; Photosystem II Protein Complex - genetics; Photosystem II Protein Complex - metabolism; Photosystem II Protein Complex - ultrastructure; Protein Binding; Protein Conformation; Protein Multimerization; Structure-Activity Relationship; Photosystem I; LHCSR3; Microscopy; Chlamydomonas reinhardtii; Electron
• ISSN: 0005-2728
• DOI: 10.1016/j.bbabio.2017.02.015

Photosynthetic organisms can thermally dissipate excess of absorbed energy in high-light conditions in a process known as non-photochemical quenching (NPQ). In the green alga Chlamydomonas reinhardtii this process depends on the presence of the light-harvesting protein LHCSR3, which is only expressed in high light. LHCSR3 has been shown to act as a quencher when associated with the Photosystem II supercomplex and to respond to pH changes, but the mechanism of quenching has not been elucidated yet. In this work we have studied the interaction between LHCSR3 and Photosystem II C S supercomplexes by single particle electron microscopy. It was found that LHCSR3 predominantly binds at three different positions and that the CP26 subunit and the LHCII trimer of C S supercomplexes are involved in binding, while we could not find evidences for a direct association of LHCSR3 with the PSII core. At all three locations LHCSR3 is present almost exclusively as a dimer.