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bioRxiv · 10.1101/118661

Structural insights into the light-driven auto-assembly process of the water-oxidizing Mn4CaO5-cluster in photosystem II

Zhang, M.·Bommer, M.·Chatterjee, R.·Hussein, R.·Yano, J.·Dau, H.·Kern, J.·Dobbek, H.·Zouni, A.
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Abstract

In plants, algae and cyanobacteria, Photosystem II (PSII) catalyzes the light-driven splitting of water at a protein-bound Mn4CaO5-cluster, the water-oxidizing complex (WOC). In the photosynthetic organisms, the light-driven formation of the WOC from dissolved metal ions is a key process because it is essential in both initial activation and continuous repair of PSII. Structural information is required for understanding of this chaperone-free metal-cluster assembly. For the first time, we obtained a structure of PSII from Thermosynechococcus elongatus without the Mn4CaO5-cluster. Surprisingly, cluster-removal leaves the positions of all coordinating amino acid residues and most nearby water molecules largely unaffected, resulting in a pre-organized ligand shell for kinetically competent and error-free photo-assembly of the Mn4CaO5-cluster. First experiments initiating (i) partial disassembly and (ii) partial re-assembly after complete depletion of the Mn4CaO5-cluster agree with a specific bi-manganese cluster, likely a di--oxo bridged pair of Mn(III) ions, as an assembly intermediate.

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Zhang, M., Bommer, M., Chatterjee, R., Hussein, R., Yano, J., Dau, H., Kern, J., Dobbek, H., Zouni, A.. 2017-03-20. Structural insights into the light-driven auto-assembly process of the water-oxidizing Mn4CaO5-cluster in photosystem II. https://doi.org/10.1101/118661

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