A Favorable Path to Domain Separation in the Orange Carotenoid Protein

In this work, we have modeled a fundamental part of the defense mechanism of Cyanobacteria against damaging effects of excess light conditions. This mechanism is part of the photoactivation cycle in the Orange Carotenoid Protein (OCP), which involves the separation of protein domains triggered by chromophore translocation. Using carefully designed metadynamics simulations, we have discovered the structural rearrangements along an energetically favorable pathway to the activated state. The structural rearrangement of OCP along its activation path has been a long-standing question, only answered now by our work.