title: Water in Photosystem II: structural, functional and mechanistic considerations.
abstract: Water is clearly important for the functioning of Photosystem II (PSII). Apart from being the very substrate that needs to be transported in this water oxidation enzyme, water is also vital for the transport of protons to and from the catalytic center as well as other important co-factors and key residues in the enzyme. The latest crystal structural data of PSII have enabled detailed analyses of the location and possible function of water molecules in the enzyme. Significant progress has also been made recently in the investigation of channels and pathways through the protein complex. Through these studies, the mechanistic significance of water for PSII is becoming increasingly clear. An overview and discussion of key aspects of the current research on water in PSII is presented here. The role of water in three other systems (aquaporin, bacteriorhodopsin and cytochrome P450) is also outlined to illustrate further points concerning the central significance that water can have, and potential applications of these ideas for continued research on PSII. It is advocated that water be seen as an integral part of the protein and far from a mere solvent.
authors: Photochemistry & Molecular Science, Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden.
authors: Katrin
authors: K
authors: Linke
authors: Felix M
authors: FM
authors: Ho
mesh_terms: D004579:Electron Transport; D007700:Kinetics; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D011522:Protons; D014867:Water / Q000737:chemistry* / Q000502:physiology
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D011522:Protons; D014867:Water; D010100:Oxygen
keywords: AQP; BRC; CYP; Channel; FTIR; Fourier transform infrared; Grotthuss; KIE; LCS; MD; MSMD; Oxygen; P(680); PBD; PSII; Photosystem II; Proton; Q(A); Q(B); Tyr(D); Tyr(Z); WT; Water; aquaporin; bR; bacterial reaction center; bacteriorhodopsin; cytochrome P450; kinetic isotope effect; large channel system; molecular dynamics; multiple steered molecular dynamics; photothermal beam deflection; the D1-Tyr161 residue in Photosystem II; the D2-Tyr160 residue in Photosystem II; the first quinone acceptor in Photosystem II/bacterial reaction center; the primary donor in Photosystem II; the second quinone acceptor in Photosystem II/bacterial reaction center; wild-type