1. A Novel Photosynthetic Strategy for Adaptation to Low-Iron Aquatic Environments
- Author
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Felisa Wolfe-Simon, Petra Fromme, Carolyn E. Lubner, Craig Jolley, Devendra Chauhan, Dorota D. Kolber, Egbert J. Boekema, Roman Kouril, I. Mihaela Folea, Su Lin, John H. Golbeck, Groningen Biomolecular Sciences and Biotechnology, and Electron Microscopy
- Subjects
Cyanobacteria ,Limiting factor ,STRESS ,Flavodoxin ,Operon ,Iron ,Adaptation, Biological ,Trimer ,Fresh Water ,ISIAB OPERON ,Photosynthesis ,Photochemistry ,CYANOBACTERIUM SYNECHOCYSTIS PCC-6803 ,Biochemistry ,Electron transfer ,IMAGE DATA ,Bacterial Proteins ,OCEAN ,PHOTOSYSTEM-I PARTICLES ,biology ,Photosystem I Protein Complex ,SYNECHOCOCCUS-ELONGATUS ,ANTENNA RING ,biology.organism_classification ,CHLOROPHYLL-BINDING PROTEIN ,Oxidative Stress ,biology.protein ,Photosynthetic membrane ,ENERGY-TRANSFER - Abstract
Iron (Fe) availability is a major limiting factor for primary production in aquatic environments. Cyanobacteria respond to Fe deficiency by derepressing the isiAB operon, which encodes the antenna protein IsiA and flavodoxin. At nanomolar Fe concentrations, a PSI-IsiA supercomplex forms, comprising a PSI trimer encircled by two complete IsiA rings. This PSI-IsiA supercomplex is the largest photosynthetic membrane protein complex yet isolated. This study presents a detailed characterization of this complex using transmission electron microscopy and ultrafast fluorescence spectroscopy. Excitation trapping and electron transfer are highly efficient, allowing cyanobacteria to avoid oxidative stress. This mechanism may be a major factor used by cyanobacteria to successfully adapt to modern low-Fe environments.
- Published
- 2011