A team of researchers around SFB 1078 project A5 including PI Prof Dr Athina Zouni and PhD student Rana Hussein, as well as PI Prof Dr Holger Dobbek and Dr Mohamed Ibrahim, aimed to provide an atomic movie for the water oxidation process in a series of publications.

In the new study published in Nature Communication, they reported a detailed discussion of four snapshots (50 μs, 150 μs, 250 μs, and 400 μs) taken during a crucial transition, S2→S3, in which the first substrate water binds to the metallo-active site. They identified the substrate water intake channel using a combined high-resolution structure of 1.89 Å. Furthermore, they described three main well-coordinated structural events within the water channels, leading to substrate insertion and proton egress during this transition.

"Understanding the proton release mechanism during the water oxidation is crucial to comprehend the entire machinery; it is also one of the critical questions that the SFB1078 project is pursuing." says Dr Mohamed Ibrahim of Prof Holger Dobbek's group at Humboldt University of Berlin, one of the first authors of the new study.

"I have been working on the crystal structure of photosynthetic membrane proteins, in particular Photosystem II, for more than two decades. The first crystal structure of Photosystem II was solved in 2001 with a resolution of 3.8 Å at the Technical University of Berlin. Therefore, the current progress is like a dream coming true." says Prof Athina Zouni, the Photosystem II Biophysics Group leader at Humboldt-Universität zu Berlin.