From manganese oxidation to water oxidation: assembly and evolution of the water-splitting complex in photosystem II.

The manganese cluster of photosystem II has been the focus of intense research aiming to understand the mechanism of HO-oxidation. Great effort has also been applied to investigating its oxidative photoassembly process, termed photoactivation that involves the light-driven incorporation of metal ions into the active MnCaO cluster. The knowledge gained on these topics has fundamental scientific significance, but may also provide the blueprints for the development of biomimetic devices capable of splitting water for solar energy applications.

The role of Ca and protein scaffolding in the formation of nature's water oxidizing complex.

Photosynthetic O evolution is catalyzed by the MnCaO cluster of the water oxidation complex of the photosystem II (PSII) complex. The photooxidative self-assembly of the MnCaO cluster, termed photoactivation, utilizes the same highly oxidizing species that drive the water oxidation in order to drive the incorporation of Mn into the high-valence MnCaO cluster. This multistep process proceeds with low quantum efficiency, involves a molecular rearrangement between light-activated steps, and is prone to photoinactivation and misassembly.

The D1-V185N mutation alters substrate water exchange by stabilizing alternative structures of the MnCa-cluster in photosystem II.

In photosynthesis, the oxygen-evolving complex (OEC) of the pigment-protein complex photosystem II (PSII) orchestrates the oxidation of water. Introduction of the V185N mutation into the D1 protein was previously reported to drastically slow O-release and strongly perturb the water network surrounding the MnCa cluster. Employing time-resolved membrane inlet mass spectrometry, we measured here the HO/HO-exchange kinetics of the fast (W) and slow (W) exchanging substrate waters bound in the S, S and S states to the MnCa cluster of PSII core complexes isolated from wild type and D1-V185N strains of Synechocystis sp.

Draft genome sequence of strain Wellendorf implicates heterotrophic versatility and bioremediation potential.

is a predominant member of hydrocarbon-contaminated environments. We here report on the genomic analysis of strain Wellendorf that was isolated from an indoor door handle. The partial genome of strain Wellendorf consists of 2,916,870 bp of DNA with 2831 protein-coding genes and 49 RNA genes.