Mutagenesis of basic residues R151 and R161 in manganese-stabilizing protein of photosystem II causes inefficient binding of chloride to the oxygen-evolving complex

An experiment to show that replacement of Arg151 or Arg161 yields proteins that have lower photosystem II (PSII) binding affinity, and are functionally deficient, even though about 2 mol of mutant MSP/mol PSII can be rebound to manganese-stabilizing protein (MSP) depleted PSII membranes. The results suggest that conserved positive charges on the manganese-stabilizing protein play a role in proper functional assembly of the protein into PSII, and consequently, in retention of Cl(super -) by the O(sub 2) - evolving complex.