title: The cyanobacterial Fluorescence Recovery Protein has two distinct activities: Orange Carotenoid Protein amino acids involved in FRP interaction.
abstract: To deal with fluctuating light condition, cyanobacteria have developed a photoprotective mechanism which, under high light conditions, decreases the energy arriving at the photochemical centers. It relies on a photoswitch, the Orange Carotenoid Protein (OCP). Once photoactivated, OCP binds to the light harvesting antenna, the phycobilisome (PBS), and triggers the thermal dissipation of the excess energy absorbed. Deactivation of the photoprotective mechanism requires the intervention of a third partner, the Fluorescence Recovery Protein (FRP). FRP by interacting with the photoactivated OCP accelerates its conversion to the non-active form and its detachment from the phycobilisome. We have studied the interaction of FRP with free and phycobilisome-bound OCP. Several OCP variants were constructed and characterized. In this article we show that OCP amino acid F299 is essential and D220 important for OCP deactivation mediated by FRP. Mutations of these amino acids did not affect FRP activity as helper to detach OCP from phycobilisomes. In addition, while mutated R60L FRP is inactive on OCP deactivation, its activity on the detachment of the OCP from the phycobilisomes is not affected. Thus, our results demonstrate that FRP has two distinct activities: it accelerates OCP detachment from phycobilisomes and then it helps deactivation of the OCP. They also suggest that different OCP and FRP amino acids could be involved in these two activities.
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Sud, Université Paris-Saclay, 91198 Gif sur Yvette, France; Institut de Biologie et Technologies de Saclay (iBiTec-S), Commissariat à l'Energie Atomique (CEA), 91191 Gif-sur-Yvette, France.
authors.forename: Adrien
authors.initials: A
authors.lastname: Thurotte
authors.affiliation: Institut de Biologie et Technologies de Saclay (iBiTec-S), Commissariat à l'Energie Atomique (CEA), 91191 Gif-sur-Yvette, France; Phycosource, 13 boulevard de l'Hautil, 95092 Cergy Cedex, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Bourcier de Carbon
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Sud, Université Paris-Saclay, 91198 Gif sur Yvette, France; Institut de Biologie et Technologies de Saclay (iBiTec-S), Commissariat à l'Energie Atomique (CEA), 91191 Gif-sur-Yvette, France.
authors.forename: Adjélé
authors.initials: A
authors.lastname: Wilson
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Sud, Université Paris-Saclay, 91198 Gif sur Yvette, France; Institut de Biologie et Technologies de Saclay (iBiTec-S), Commissariat à l'Energie Atomique (CEA), 91191 Gif-sur-Yvette, France.
authors.forename: Léa
authors.initials: L
authors.lastname: Talbot
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Sud, Université Paris-Saclay, 91198 Gif sur Yvette, France; Institut de Biologie et Technologies de Saclay (iBiTec-S), Commissariat à l'Energie Atomique (CEA), 91191 Gif-sur-Yvette, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Cot
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Sud, Université Paris-Saclay, 91198 Gif sur Yvette, France; Institut de Biologie et Technologies de Saclay (iBiTec-S), Commissariat à l'Energie Atomique (CEA), 91191 Gif-sur-Yvette, France.
authors.forename: Rocio
authors.initials: R
authors.lastname: López-Igual
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris-Sud, Université Paris-Saclay, 91198 Gif sur Yvette, France; Institut de Biologie et Technologies de Saclay (iBiTec-S), Commissariat à l'Energie Atomique (CEA), 91191 Gif-sur-Yvette, France. Electronic address: diana.kirilovsky@cea.fr.
authors.forename: Diana
authors.initials: D
authors.lastname: Kirilovsky
mesh_terms: D000596:Amino Acids / Q000502:physiology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D005453:Fluorescence
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; C109473:orange carotenoid protein, Synechocystis
keywords: Cyanobacteria; Fluorescence Recovery Protein; Non-photochemical quenching; Orange Carotenoid Protein; Photoprotection; Phycobilisome