Structure-function-dynamics relationships in the peculiar Planktothrix PCC7805 OCP1: Impact of his-tagging and carotenoid type

• Main Authors: Andreeva, E.A (Author), Burdzinski, G. (Author), Colletier, J.-P (Author), Hartmann, E. (Author), Kirilovsky, D. (Author), Niziński, S.J (Author), Schlichting, I. (Author), Sliwa, M. (Author), Talbot, L. (Author), Wilson, A. (Author)
• Format: Article
• Language: English
• Published: Elsevier B.V. 2022
• Subjects: Cyanobacteria; Flash photolysis; Photosynthetic pigments; Structure function relationships; X-ray diffraction
• Online Access: View Fulltext in Publisher

 The orange carotenoid protein (OCP) is a photoactive protein involved in cyanobacterial photoprotection. Here, we report on the functional, spectral and structural characteristics of the peculiar Planktothrix PCC7805 OCP (Plankto-OCP). We show that this OCP variant is characterized by higher photoactivation and recovery rates, and a stronger energy-quenching activity, compared to other OCP studied thus far. We characterize the effect of the functionalizing carotenoid and of his-tagging on these reactions, and identify the time scales on which these modifications affect photoactivation. The presence of a his-tag at the C-terminus has a large influence on photoactivation, thermal recovery and PBS-fluorescence quenching, and likewise for the nature of the carotenoid that additionally affects the yield and characteristics of excited states and the ns-s dynamics of photoactivated OCP. By solving the structures of Plankto-OCP in the ECN- and CAN-functionalized states, each in two closely-related crystal forms, we further unveil the molecular breathing motions that animate Plankto-OCP at the monomer and dimer levels. We finally discuss the structural changes that could explain the peculiar properties of Plankto-OCP. © 2022