title: Relationship between excitation energy transfer, trapping, and antenna size in photosystem II.
abstract: We present a systematic study of the effect of antenna size on energy transfer and trapping in photosystem II. Time-resolved fluorescence experiments have been used to probe a range of particles isolated from both higher plants and the cyanobacterium Synechocystis 6803. The isolated reaction center dynamics are represented by a quasi-phenomenological model that fits the extensive time-resolved data from photosystem II reaction centers and reaction center mutants. This representation of the photosystem II "trapping engine" is found to correctly predict the extent of, and time scale for, charge separation in a range of photosystem II particles of varying antenna size (8-250 chlorins). This work shows that the presence of the shallow trap and slow charge separation kinetics, observed in isolated D1/D2/cyt b559 reaction centers, are indeed retained in larger particles and that these properties are reflected in the trapping dynamics of all larger photosystem II preparations. A shallow equilibrium between the antennae and reaction center in photosystem II will certainly facilitate regulation via nonphotochemical quenching, and one possible interpretation of these findings is therefore that photosystem II is optimized for regulation rather than for efficiency.
authors: Departments of Biochemistry and Chemistry, Imperial College, London SW7 2AY, UK.
authors: L M
authors: LM
authors: Barter
authors: M
authors: M
authors: Bianchietti
authors: C
authors: C
authors: Jeans
authors: M J
authors: MJ
authors: Schilstra
authors: B
authors: B
authors: Hankamer
authors: B A
authors: BA
authors: Diner
authors: J
authors: J
authors: Barber
authors: J R
authors: JR
authors: Durrant
authors: D R
authors: DR
authors: Klug
mesh_terms: D002734:Chlorophyll / Q000737:chemistry*; D000458:Cyanobacteria; D003573:Cytochrome b Group / Q000737:chemistry; D004735:Energy Transfer; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes; D008956:Models, Chemical; D018532:Pisum sativum; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045332:Photosystem II Protein Complex; D011166:Porphyrins / Q000737:chemistry
chemical_list: D003573:Cytochrome b Group; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D011166:Porphyrins; C083100:photosystem II, chlorophyll binding protein, CP-43; C422369:photosystem II, psbA subunit; C070970:photosystem II, chlorophyll-binding protein, CP-47; D002734:Chlorophyll; C006969:chlorin; C019313:cytochrome b559