title: Phycocyanin sensitizes both photosystem I and photosystem II in cryptophyte Chroomonas CCMP270 cells.
abstract: This article presents an investigation of the energy migration dynamics in intact cells of the unicellular photosynthetic cryptophyte Chroomonas CCMP270 by steady-state and time-resolved fluorescence measurements. By kinetic modeling of the fluorescence data on chlorophyll and phycocyanin 645 excitation (at 400 and 582 nm respectively), it has been possible to show the excited state energy distribution in the photosynthetic antenna of this alga. Excitation energy from phycocyanin 645 is distributed nearly equally between photosystem I and photosystem II with very high efficiency on a 100-ps timescale. The excitation energy trapping times for both photosystem I ( approximately 30 ps) and photosystem I (200 and approximately 540 ps) correspond well to those obtained from experiments on isolated photosystems. The results are compared with previous results for another cryptophyte species, Rhodomonas CS24, and suggest a similar membrane organization for the cryptophytes with the phycobiliproteins tightly packed in the thylakoid lumen around the periphery of the photosystems.
authors.affiliation: Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, 1081 HV Amsterdam.
authors.forename: Chantal D
authors.initials: CD
authors.lastname: van der Weij-De Wit
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Doust
authors.forename: Ivo H M
authors.initials: IH
authors.lastname: van Stokkum
authors.forename: Jan P
authors.initials: JP
authors.lastname: Dekker
authors.forename: Krystyna E
authors.initials: KE
authors.lastname: Wilk
authors.forename: Paul M G
authors.initials: PM
authors.lastname: Curmi
authors.forename: Rienk
authors.initials: R
authors.lastname: van Grondelle
mesh_terms: D000818:Animals; D002460:Cell Line; D044785:Cryptophyta / Q000737:chemistry; D003627:Data Interpretation, Statistical; D056890:Eukaryota / Q000378:metabolism* / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D007700:Kinetics; D008027:Light; D045342:Light-Harvesting Protein Complexes; D008856:Microscopy, Fluorescence / Q000379:methods; D010785:Photophosphorylation; D010788:Photosynthesis; D045331:Photosystem I Protein Complex / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000502:physiology*; D045524:Phycobilisomes; D010798:Phycocyanin / Q000737:chemistry*
chemical_list: D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D045524:Phycobilisomes; D010798:Phycocyanin