Journal ArticleDOI
Towards complete cofactor arrangement in the 3.0 Å resolution structure of photosystem II
TLDR
The most complete cyanobacterial photosystem II structure obtained so far is described, showing locations of and interactions between 20 protein subunits and 77 cofactors per monomer, and provides information about the Mn4Ca cluster, where oxidation of water takes place.Abstract:
Oxygenic photosynthesis in plants, algae and cyanobacteria is initiated at photosystem II, a homodimeric multisubunit protein-cofactor complex embedded in the thylakoid membrane. Photosystem II captures sunlight and powers the unique photo-induced oxidation of water to atmospheric oxygen. Crystallographic investigations of cyanobacterial photosystem II have provided several medium-resolution structures (3.8 to 3.2 A) that explain the general arrangement of the protein matrix and cofactors, but do not give a full picture of the complex. Here we describe the most complete cyanobacterial photosystem II structure obtained so far, showing locations of and interactions between 20 protein subunits and 77 cofactors per monomer. Assignment of 11 beta-carotenes yields insights into electron and energy transfer and photo-protection mechanisms in the reaction centre and antenna subunits. The high number of 14 integrally bound lipids reflects the structural and functional importance of these molecules for flexibility within and assembly of photosystem II. A lipophilic pathway is proposed for the diffusion of secondary plastoquinone that transfers redox equivalents from photosystem II to the photosynthetic chain. The structure provides information about the Mn4Ca cluster, where oxidation of water takes place. Our study uncovers near-atomic details necessary to understand the processes that convert light to chemical energy.read more
Citations
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Powering the planet: Chemical challenges in solar energy utilization
Nathan S. Lewis,Daniel G. Nocera +1 more
TL;DR: Solar energy is by far the largest exploitable resource, providing more energy in 1 hour to the earth than all of the energy consumed by humans in an entire year, and if solar energy is to be a major primary energy source, it must be stored and dispatched on demand to the end user.
Journal ArticleDOI
In Situ Formation of an Oxygen-Evolving Catalyst in Neutral Water Containing Phosphate and Co2+
TL;DR: A catalyst that forms upon the oxidative polarization of an inert indium tin oxide electrode in phosphate-buffered water containing cobalt (II) ions is reported that not only forms in situ from earth-abundant materials but also operates in neutral water under ambient conditions.
Journal ArticleDOI
Production and scavenging of reactive oxygen species in chloroplasts and their functions.
TL;DR: The reaction centers of PSI and PSII in chloroplast thylakoids are the major generation site of reactive oxygen species (ROS) and the primary reduced product was identified.
Journal ArticleDOI
Proton-Coupled Electron Transfer
David R. Weinberg,Christopher J. Gagliardi,Jonathan F. Hull,Christine Fecenko Murphy,Caleb A. Kent,Brittany C. Westlake,Amit Paul,Daniel H. Ess,Dewey G. McCafferty,Thomas J. Meyer +9 more
TL;DR: Proton-coupled electron transfer is an important mechanism for charge transfer in a wide variety of systems including biology- and materials-oriented venues and several are reviewed.
Journal ArticleDOI
Photosynthetic energy conversion: natural and artificial
TL;DR: Can PSII be exploited through increased use of biomass as an energy source and, more importantly, can the energy/CO2 problem be addressed by developing new photochemical technologies which mimic the natural system?
References
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Journal ArticleDOI
Architecture of the Photosynthetic Oxygen-Evolving Center
TL;DR: The data strongly suggest that the OEC contains a cubane-like Mn3CaO4 cluster linked to a fourth Mn by a mono-μ-oxo bridge, and the details of the surrounding coordination sphere of the metal cluster and the implications for a possible oxygen-evolving mechanism are discussed.
Journal ArticleDOI
Cooperation of charges in photosynthetic o2 evolution–i. a linear four step mechanism
TL;DR: The evolution of O2 in weak light and light flashes is studied to analyze the interactions between light induced O2 precursors and their decay in darkness and the data are compatible with a linear four step mechanism in which a trapping center successively accumulates four + charges.
Journal ArticleDOI
Crystal structure of photosystem II from Synechococcus elongatus at 3.8 A resolution.
Athina Zouni,Horst Tobias Witt,Jan Kern,Petra Fromme,Norbert Krauss,Wolfram Saenger,Peter Orth +6 more
TL;DR: The X-ray structure of photosystem II is described on the basis of crystals fully active in water oxidation, shows how protein subunits and cofactors are spatially organized and the larger subunits are assigned and the locations and orientations of the cofacters are defined.
Journal ArticleDOI
Crystal structure of oxygen-evolving photosystem II from Thermosynechococcus vulcanus at 3.7-A resolution
Nobuo Kamiya,Jian Ren Shen +1 more
TL;DR: The crystal structure of PSII from another thermophilic cyanobacterium, Thermosynechococcus vulcanus, is obtained and the arrangement of chlorophylls and cofactors, including two β-carotenes recently identified in a region close to the reaction center, provided important clues to the secondary electron transfer pathways around the reaction centre.
Journal ArticleDOI
Structure of the Cytochrome b6f Complex of Oxygenic Photosynthesis: Tuning the Cavity
TL;DR: The dimeric b6f complex from the thermophilic cyanobacterium Mastigocladus laminosus reveals a large quinone exchange cavity, stabilized by lipid, in which plastoquinone, a quin one-analog inhibitor, and a novel heme are bound.