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IN BRIEF

Energy Dissipation: New Role for a Carotenoid Protein in Cyanobacteria

Photosynthetic organisms have developed multiple mechanisms to protect the photosynthetic apparatus from high light stress. Plants and algae exhibit thermal dissipation of excitation energy in the membrane-bound light-harvesting complex of photosystem II (LHCII). In most species of cyanobacteria, which lack LHCII, light is captured by the phycobilisome, a membrane-extrinsic complex attached to the outer surface of thylakoid membranes. Recent work has suggested that phycobilisomes display an alternate mechanism for dissipating excess absorbed energy. Wilson et al. (pages 992–1007) show that this photoprotective mechanism, characterized by blue light–induced fluorescence quenching, is indeed phycobilisome related and that a soluble carotenoid binding protein (OCP), encoded by the slr1963 gene in Synechocystis PCC 6803, plays an essential role in this process. The data suggest that OCP, which interacts with the thylakoids, acts as both the photoreceptor and as the mediator of the reduction of the amount of energy transferred from the phycobilisomes to the photosystems.

View larger version (154K): [in this window] [in a new window]   Immunogold labeling of Synechocystis cells containing an OCP-GFP fusion protein shows close association of the protein with thylakoid membranes.

Related articles in Plant Cell:

A Soluble Carotenoid Protein Involved in Phycobilisome-Related Energy Dissipation in Cyanobacteria

Adjélé Wilson, Ghada Ajlani, Jean-Marc Verbavatz, Imre Vass, Cheryl A. Kerfeld, and Diana Kirilovsky
Plant Cell 2006 18: 992-1007. [Abstract] [Full Text]  

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in Plant Cell Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Eckardt, N. A. Search for Related Content PubMed PubMed Citation Articles by Eckardt, N. A. Agricola Articles by Eckardt, N. A.