Mutation of a metal ligand stabilizes the high-spin form of the S<inf>2</inf> state in the O<inf>2</inf>-producing Mn<inf>4</inf>CaO<inf>5</inf> cluster of photosystem II
Issued Date
2023-01-01
Resource Type
ISSN
01668595
eISSN
15735079
Scopus ID
2-s2.0-85146515594
Journal Title
Photosynthesis Research
Rights Holder(s)
SCOPUS
Bibliographic Citation
Photosynthesis Research (2023)
Suggested Citation
Chakarawet K., Debus R.J., Britt R.D. Mutation of a metal ligand stabilizes the high-spin form of the S<inf>2</inf> state in the O<inf>2</inf>-producing Mn<inf>4</inf>CaO<inf>5</inf> cluster of photosystem II. Photosynthesis Research (2023). doi:10.1007/s11120-023-00998-z Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/81494
Title
Mutation of a metal ligand stabilizes the high-spin form of the S<inf>2</inf> state in the O<inf>2</inf>-producing Mn<inf>4</inf>CaO<inf>5</inf> cluster of photosystem II
Author(s)
Author's Affiliation
Other Contributor(s)
Abstract
The residue D1-D170 bridges Mn4 with the Ca ion in the O2-evolving Mn4CaO5 cluster of Photosystem II. Recently, the D1-D170E mutation was shown to substantially alter the Sn+1-minus-Sn FTIR difference spectra [Debus RJ (2021) Biochemistry 60:3841-3855]. The mutation was proposed to alter the equilibrium between different Jahn–Teller conformers of the S1 state such that (i) a different S1 state conformer is stabilized in D1-D170E than in wild-type and (ii) the S1 to S2 transition in D1-D170E produces a high-spin form of the S2 state rather than the low-spin form that is produced in wild-type. In this study, we employed EPR spectroscopy to test if a high-spin form of the S2 state is formed preferentially in D1-D170E PSII. Our data show that illumination of dark-adapted D1-D170E PSII core complexes does indeed produce a high-spin form of the S2 state rather than the low-spin multiline form that is produced in wild-type. This observation provides further experimental support for a change in the equilibrium between S state conformers in both the S1 and S2 states in a site-directed mutant that retains substantial O2 evolving activity.
