A photoactive carotenoid protein acting as light intensity sensor

Adjélé Wilson (1, 2, 3) , Claire Punginelli (1, 2, 3) , Andrew Gall (1, 2, 3) , Cosimo Bonetti (4) , Maxime Alexandre (4) , Jean-Marc Routaboul (5) , Cheryl A. Kerfeld (6, 7) , Rienk van Grondelle (4) , Bruno Robert (1, 2, 3) , John T.M. Kennis (4) , Diana Kirilovsky (1, 2, 3)

1 CEA - Commissariat à l'énergie atomique et aux énergies alternatives
2 Institut de Biologie et Technologies de Saclay
3 CNRS - Centre National de la Recherche Scientifique
4 Department of Physics and Astronomy [Amsterdam]
5 IJPB - Institut Jean-Pierre Bourgin
6 United States Department of Energy
7 Department of Plant and Microbial Biology

Intense sunlight is dangerous for photosynthetic organisms. Cyanobacteria, like plants, protect themselves from light-induced stress by dissipating excess absorbed energy as heat. Recently, it was discovered that a soluble orange carotenoid protein, the OCP, is essential for this photoprotective mechanism. Here we show that the OCP is also a member of the family of photoactive proteins; it is a unique example of a photoactive protein containing a carotenoid as the photoresponsive chromophore. Upon illumination with blue-green light, the OCP undergoes a reversible transformation from its dark stable orange form to a red "active" form. The red form is essential for the induction of the photoprotective mechanism. The illumination induces structural changes affecting both the carotenoid and the protein. Thus, the OCP is a photoactive protein that senses light intensity and triggers photoprotection.

Mots clés: cyanobacteria; nonphotochemical quenching; photoprotection; phycobilisome

Domaines: Sciences du Vivant [q-bio]

Adjélé Wilson, Claire Punginelli, Andrew Gall, Cosimo Bonetti, Maxime Alexandre, et al.. A photoactive carotenoid protein acting as light intensity sensor. Proceedings of the National Academy of Sciences of the United States of America, 2008, 105 (33), pp.12075-12080. ⟨10.1073/pnas.0804636105⟩. ⟨hal-01203971⟩