RRC ID 28422
Author Cardol P, Bailleul B, Rappaport F, Derelle E, Béal D, Breyton C, Bailey S, Wollman FA, Grossman A, Moreau H, Finazzi G.
Title An original adaptation of photosynthesis in the marine green alga Ostreococcus.
Journal Proc Natl Acad Sci U S A
Abstract Adaptation of photosynthesis in marine environment has been examined in two strains of the green, picoeukaryote Ostreococcus: OTH95, a surface/high-light strain, and RCC809, a deep-sea/low-light strain. Differences between the two strains include changes in the light-harvesting capacity, which is lower in OTH95, and in the photoprotection capacity, which is enhanced in OTH95. Furthermore, RCC809 has a reduced maximum rate of O(2) evolution, which is limited by its decreased photosystem I (PSI) level, a possible adaptation to Fe limitation in the open oceans. This decrease is, however, accompanied by a substantial rerouting of the electron flow to establish an H(2)O-to-H(2)O cycle, involving PSII and a potential plastid plastoquinol terminal oxidase. This pathway bypasses electron transfer through the cytochrome b(6)f complex and allows the pumping of "extra" protons into the thylakoid lumen. By promoting the generation of a large DeltapH, it facilitates ATP synthesis and nonphotochemical quenching when RCC809 cells are exposed to excess excitation energy. We propose that the diversion of electrons to oxygen downstream of PSII, but before PSI, reflects a common and compulsory strategy in marine phytoplankton to bypass the constraints imposed by light and/or nutrient limitation and allow successful colonization of the open-ocean marine environment.
Volume 105(22)
Pages 7881-6
Published 2008-6-3
DOI 10.1073/pnas.0802762105
PII 0802762105
PMID 18511560
PMC PMC2409423
MeSH Acclimatization* / radiation effects Chlorophyta / enzymology Chlorophyta / physiology* Chlorophyta / radiation effects Cytochrome b6f Complex / metabolism Electron Transport Light Oxygen / metabolism Photosynthesis* / radiation effects Photosystem I Protein Complex / metabolism* Photosystem II Protein Complex / metabolism* Seawater
IF 9.412
Times Cited 102
Algae NIES-2674