D1-S169A Substitution of Photosystem II Perturbs Water Oxidation

• DOI: 10.1021/acs.biochem.8b01184
• Publication Date: 2019-02-01T21:01:04Z
• Authors: Ipsita Ghosh; Gourab Banerjee; Christopher J. Kim; Krystle Reiss; Victor S. Batista; Richard J. Debus; Gary W. Brudvig
• Keywords: Oxygen evolution

In photosystem II (PSII), photosynthetic water oxidation occurs at the tetramanganese-calcium cluster that cycles through light-induced intermediates (S0-S4) to produce oxygen from two substrate waters. The surrounding hydrogen-bonded amino acid residues and waters form channels facilitate proton transfer delivery, thereby ensuring efficient oxidation. residue D1-S169 lies in "narrow" channel forms hydrogen bonds with Mn4CaO5 via W1 Wx. To probe role of narrow substrate-water binding, we studied D1-S169A mutation. PSII core complexes isolated mutant cells exhibit inefficient S-state cycling delayed evolution. S2-state multiline EPR spectrum differed significantly wild-type, FTIR difference spectra showed mutation strongly perturbs extensive network extends least D1-Y161 (YZ) D1-D61. These results imply a possible egress or delivery.