Abstract
Exposure of cyanobacterial or red algal cells to high light has been proposed to lead to excitonic decoupling of the phycobilisome antennae (PBSs) from the reaction centers. Here we show that excitonic decoupling of PBSs of Synechocystis sp. PCC 6803 is induced by strong light at wavelengths that excite either phycobilin or chlorophyll pigments. We further show that decoupling is generally followed by disassembly of the antenna complexes and/or their detachment from the thylakoid membrane. Based on a previously proposed mechanism, we suggest that local heat transients generated in the PBSs by non-radiative energy dissipation lead to alterations in thermo-labile elements, likely in certain rod and core linker polypeptides. These alterations disrupt the transfer of excitation energy within and from the PBSs and destabilize the antenna complexes and/or promote their dissociation from the reaction centers and from the thylakoid membranes. Possible implications of the aforementioned alterations to adaptation of cyanobacteria to light and other environmental stresses are discussed.
| Original language | English |
|---|---|
| Pages (from-to) | 319-327 |
| Number of pages | 9 |
| Journal | Biochimica et Biophysica Acta - Bioenergetics |
| Volume | 1817 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 2012 |
Bibliographical note
Funding Information:We thank Vlad Brumfeld (Weizmann Institute of Science) for assistance with the spectroscopic measurements. We also thank Dana Charuvi, Ruti Kapon, and Onie Tsabari (Weizmann Institute of Science) for helpful comments and suggestions. This work was supported by grants from the Israel Science Foundation ( No. 1005/07 , Z.R.), the German Research Foundation (DFG, SFB 480 , project C1, M.R.), the German Federal Ministry of Education and Research (BMBF, project Bio-H 2 , G.B. and M.R.), and the EU project Solar-H 2 (M.R.).
Keywords
- Cyanobacteria
- Energetic decoupling
- Energy transfer
- FRAP
- Photoprotection
- Phycobilisomes