Structural organisation of phycobilisomes from Synechocystis sp. strain PCC6803 and their interaction with the membrane.

Department of Biophysical Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Biochimica et Biophysica Acta (Impact Factor: 4.66). 02/2009; 1787(4):272-9. DOI: 10.1016/j.bbabio.2009.01.009
Source: PubMed

ABSTRACT In cyanobacteria, the harvesting of light energy for photosynthesis is mainly carried out by the phycobilisome - a giant, multi-subunit pigment-protein complex. This complex is composed of heterodimeric phycobiliproteins that are assembled with the aid of linker polypeptides such that light absorption and energy transfer to photosystem II are optimised. In this work we have studied, using single particle electron microscopy, the phycobilisome structure in mutants lacking either two or all three of the phycocyanin hexamers. The images presented give much greater detail than those previously published, and in the best two-dimensional projection maps a resolution of 13 A was achieved. As well as giving a better overall picture of the assembly of phycobilisomes, these results reveal new details of the association of allophycocyanin trimers within the core. Insights are gained into the attachment of this core to the membrane surface, essential for efficient energy transfer to photosystem II. Comparison of projection maps of phycobilisomes with and without reconstituted ferredoxin:NADP oxidoreductase suggests a location for this enzyme within the complex at the rod-core interface.

1 Follower
  • [Show abstract] [Hide abstract]
    ABSTRACT: State transition and non-photochemical fluorescence quenching in cyanobacteria are short-term adaptations of photosynthetic apparatus to changes in light quality and intensity, however, the kinetic details and relationship are still not clear. In this work, time-dependent 77K fluorescence spectra were monitored for cyanobacterium Synechocystis PCC 6803 cells under blue, orange and blue-green light in a series of intensities. The characteristic fluorescence signals indicated state transition taking place exclusively under 430-450 or 580-600nm light or 480-550nm light at the intensities ⩽150μEm(-2)s(-1) to achieve a conserved level with variable rate constant. Under 480-500nm or 530-550nm light at the intensities ⩾160μEm(-2)s(-1), state transition took place at first but stopped as soon as the fluorescence quenching appeared. The dependence of appearance, induction period, level and rate constant for the quenching on light intensity suggests that a critical concentration of photo-activated OCPs is necessary and may be achieved by a dynamic equilibrium between the activation and deactivation under light. Copyright © 2014. Published by Elsevier B.V.
    Journal of Photochemistry and Photobiology B Biology 12/2014; 142C:169-177. DOI:10.1016/j.jphotobiol.2014.10.023 · 2.80 Impact Factor
  • Source
    International Journal of Pharma and Bio Sciences 01/2011; 2(4):446-454. · 2.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: State transition and blue-green light-induced fluorescence quenching are two short-term processes in cyanobacteria. The details of their kinetics and the relationship between these processes have not been elucidated. In this work, these two processes were studied in the wild-type cyanobacterium Synechocystis PCC 6803 cells as well as in apcD (-) and apcF (-) mutants by monitoring their time-dependent 77 K fluorescence responses to blue-green light (430-540 nm) at a series of intensities ranging from 20-800 A mu E m(-2) s(-1). The lowest light intensity to induce fluorescence quenching in wild-type cells was 160 A mu E m(-2) s(-1) under the selected experimental conditions, while state transition took place at the intensities lower than 160 A mu E m(-2) s(-1) at a conservative level, but at variable rates. The quenching level increased at intensities higher than 160 A mu E m(-2) s(-1), reaching the maximum level at intensities equal to or higher than 200 A mu E m(-2) s(-1). Fluorescence kinetics indicated that both the length of the induction period and time required to reach the maximum level were functions of light intensity. State transitions as well as fluorescence quenching took place in both wild-type and mutant cells, but might involve different mechanisms.
    Chinese Science Bulletin 12/2014; 59(34):4712-4719. DOI:10.1007/s11434-014-0533-x · 1.37 Impact Factor

Full-text (2 Sources)

Available from
Jun 3, 2014