Although it is known that the photoactivated OCPr protects
the photosynthetic RCs by close interaction with the PBS and
quenches the excess energy absorbed by PBS, the binding site
remains elusive, and this greatly hampers the elucidation of the
quenching mechanism. On the basis of our cross-linking
experiments, we propose here a model of PBS−OCP
interaction (Figure 3) by using model program i-TASSER.