Mutation Val235Ala weakens binding of the 33-kDa manganese stabilizing protein of photosystem II to one of two sites

The binding of MSP with [V235A]MSP was analyzed to characterize the MSP binding sites and their role in the activity of the photosystem (PS) II. MSP prevented the binding of [V235A]MSP to PSII due to the direct competition of the proteins for two similar binding sites in PS II. Similar structural features were also required for the stable binding of MSP to the two binding sites in PS II. Furthermore, the binding of the wild-type protein to one PS II site strengthened the binding of the mutant protein in the other MSP binding site.