title: Identification of common motifs in the regulation of light harvesting: The case of cyanobacteria IsiA.
abstract: When cyanobacteria are grown under iron-limited or other oxidative stress conditions the iron stress inducible pigment-protein IsiA is synthesized in variable amounts. IsiA accumulates in aggregates inside the photosynthetic membrane that strongly dissipate chlorophyll excited state energy. In this paper we applied Stark fluorescence (SF) spectroscopy at 77K to IsiA aggregates to gain insight into the nature of the emitting and energy dissipating state(s). Our study shows that two emitting states are present in the system, one emitting at 684 nm and the other emitting at about 730 nm. The new 730 nm state exhibits strongly reduced fluorescence (F) together with a large charge transfer character. We discuss these findings in the light of the energy dissipation mechanisms involved in the regulation of photosynthesis in plants, cyanobacteria and diatoms. Our results suggest that photosynthetic organisms have adopted common mechanisms to cope with the deleterious effects of excess light under unfavorable growth conditions.
authors.affiliation: Biophysics of Photosynthesis/Physics of Energy, Department of Physics Astronomy, Faculty of Sciences, VU University Amsterdam, The Netherlands; Department of Physics, University of Dhaka, Dhaka 1000, Bangladesh. Electronic address: m.d.wahadoszamen@vu.nl.
authors.forename: Md
authors.initials: M
authors.lastname: Wahadoszamen
authors.affiliation: Biophysics of Photosynthesis/Physics of Energy, Department of Physics Astronomy, Faculty of Sciences, VU University Amsterdam, The Netherlands.
authors.forename: Sandrine
authors.initials: S
authors.lastname: D'Haene
authors.affiliation: Biophysics of Photosynthesis/Physics of Energy, Department of Physics Astronomy, Faculty of Sciences, VU University Amsterdam, The Netherlands; Department of Physics, Jagannath University, Dhaka 1100, Bangladesh.
authors.forename: Anjue Mane
authors.initials: AM
authors.lastname: Ara
authors.affiliation: Biophysics of Photosynthesis/Physics of Energy, Department of Physics Astronomy, Faculty of Sciences, VU University Amsterdam, The Netherlands.
authors.forename: Elisabet
authors.initials: E
authors.lastname: Romero
authors.affiliation: Biophysics of Photosynthesis/Physics of Energy, Department of Physics Astronomy, Faculty of Sciences, VU University Amsterdam, The Netherlands.
authors.forename: Jan P
authors.initials: JP
authors.lastname: Dekker
authors.affiliation: Biophysics of Photosynthesis/Physics of Energy, Department of Physics Astronomy, Faculty of Sciences, VU University Amsterdam, The Netherlands.
authors.forename: Rienk van
authors.initials: RV
authors.lastname: Grondelle
authors.affiliation: Biophysics of Photosynthesis/Physics of Energy, Department of Physics Astronomy, Faculty of Sciences, VU University Amsterdam, The Netherlands. Electronic address: r.berera@vu.nl.
authors.forename: Rudi
authors.initials: R
authors.lastname: Berera
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism*; D000458:Cyanobacteria / Q000254:growth & development / Q000378:metabolism*; D005453:Fluorescence; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology*; D045331:Photosystem I Protein Complex / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013312:Stress, Physiological
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex; D002734:Chlorophyll; C076726:chlorophyll A binding protein CP43, Cyanobacteria
keywords: Charge transfer states; Cyanobacteria; IsiA complex; Light-harvesting antenna; Photoprotective energy dissipation; Stark spectroscopy