Do you need a protein? There are lots of small-molecule PS II inhibitors, DCMU, atrazine, etc., that inhibit PS II function but do not affect other parts of the cell unless at excess concentration.
Yes, I wish to establish a system, where I can switch on or off photosystem without any external application of a inhibitor, while other organelles remain unaffected. So, I am in search of a protein that can block PS.