Details

Autor(en) / Beteiligte

• Tokutsu, Ryutaro
• Kato, Nobuyasu
• Bui, Khanh Huy
• Ishikawa, Takashi
• Minagawa, Jun

Titel

Revisiting the Supramolecular Organization of Photosystem II in Chlamydomonas reinhardtii

Ist Teil von

• The Journal of biological chemistry, 2012-09, Vol.287 (37), p.31574-31581

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2012

Quelle

MEDLINE

Beschreibungen/Notizen

• Photosystem II (PSII) is a multiprotein complex that splits water and initiates electron transfer in photosynthesis. The central part of PSII, the PSII core, is surrounded by light-harvesting complex II proteins (LHCIIs). In higher plants, two or three LHCII trimers are seen on each side of the PSII core whereas only one is seen in the corresponding positions in Chlamydomonas reinhardtii, probably due to the absence of CP24, a minor monomeric LHCII. Here, we re-examined the supramolecular organization of the C. reinhardtii PSII-LHCII supercomplex by determining the effect of different solubilizing detergents. When we solubilized the thylakoid membranes with n-dodecyl-β-d-maltoside (β-DM) or n-dodecyl-α-d-maltoside (α-DM) and subjected them to gel filtration, we observed a clear difference in molecular mass. The α-DM-solubilized PSII-LHCII supercomplex bound twice more LHCII than the β-DM-solubilized supercomplex and retained higher oxygen-evolving activity. Single-particle image analysis from electron micrographs of the α-DM-solubilized and negatively stained supercomplex revealed that the PSII-LHCII supercomplex had a novel supramolecular organization, with three LHCII trimers attached to each side of the core. Background: Light-harvesting complex II (LHCII) proteins associate with photosystem II (PSII) to form a supercomplex. Results: We isolated an active PSII supercomplex from thylakoids solubilized with dodecyl-α-d-maltoside and visualized it in a large projection map with an electron microscope. Conclusion: The novel PSII supercomplex harbored three LHCII trimers on each side. Significance: The large and active PSII-LHCII supercomplex is engaged in green algal photosynthesis.