title: A megacomplex composed of both photosystem reaction centres in higher plants.
abstract: Throughout the history of oxygen evolution, two types of photosystem reaction centres (PSI and PSII) have worked in a coordinated manner. The oxygen evolving centre is an integral part of PSII, and extracts an electron from water. PSI accepts the electron, and accumulates reducing power. Traditionally, PSI and PSII are thought to be spatially dispersed. Here, we show that about half of PSIIs are physically connected to PSIs in Arabidopsis thaliana. In the PSI-PSII complex, excitation energy is transferred efficiently between the two closely interacting reaction centres. PSII diverts excitation energy to PSI when PSII becomes closed-state in the PSI-PSII complex. The formation of PSI-PSII complexes is regulated by light conditions. Quenching of excess energy by PSI might be one of the physiological functions of PSI-PSII complexes.
authors: 1] Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan [2] CREST, JST, Sapporo 060-0819, Japan.
authors: M
authors: M
authors: Yokono
authors: 1] Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan [2] CREST, JST, Sapporo 060-0819, Japan.
authors: A
authors: A
authors: Takabayashi
authors: 1] Molecular Photoscience Research Center, Kobe University, Kobe 657-8501, Japan [2] CREST, JST, Kobe 657-8501, Japan.
authors: S
authors: S
authors: Akimoto
authors: 1] Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan [2] CREST, JST, Sapporo 060-0819, Japan.
authors: A
authors: A
authors: Tanaka
mesh_terms: D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000502:physiology*; D004579:Electron Transport; D004735:Energy Transfer; D008027:Light; D010100:Oxygen / Q000378:metabolism*; D045331:Photosystem I Protein Complex / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D010100:Oxygen