Fluorescence and Circular Dichroism Studies on the Phycoerythrocyanins From the Cyanobacterium

Saı̈, Pierre; Siebzehnrübl, S.; Mahajan, Sudha; Scheer, Hugo

doi:10.1111/j.1751-1097.1993.tb02257.x

Cited by 17 publications

(6 citation statements)

References 20 publications

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“…This property, which is reminiscent of the higher plant sensory receptor phytochrome [6], has been attributed to the a84 PVB chromophore [7][8][9][10]. Studies have also indicated that the extent of reversible photochemistry in PEC increases with decreasing size of the aggregate and vice versa [7,9]. This dual feature of light harvesting and reversible photochemistry makes PEC unique in the sense that it is probably the only structurally defined cyanobacterial biliprotein studied so far that exhibits reversible photochemistry in the native state.…”

Section: Introductionmentioning

confidence: 92%

“…2 and 3. They have been discussed in detail previously [9], and therefore we only need to summarize those features which are essential \\~\ \\\\ ~.…”

Section: Absorption and Stationary Fluorescencementioning

confidence: 99%

“…Westiellopsis prolifica was obtained as an agar slant from the National Facility for Blue-Green Algae, Indian Agricultural Research Institute, New Delhi, India, and was grown in batch cultures of 5-10 1 in BG-11 medium as described previously [9]. Intact phycobilisomes were isolated according to a new procedure [9].…”

Section: Methodsmentioning

confidence: 99%

“…Intact phycobilisomes were isolated according to a new procedure [9]. Two PEC fractions were obtained from the isolated phycobilisomes after dissociating the latter by dialysis at 4 °C against potassium phosphate buffer (5 raM, pH 7.0).…”

Section: Methodsmentioning

confidence: 99%

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Photophysics of phycoerythrocyanins from the cyanobacterium Westiellopsis prolifica studied by time-resolved fluorescence and coherent anti-Stokes Raman scattering spectroscopy

Schneider¹,

Jäger²,

Prenzel³

et al. 1994

Journal of Photochemistry and Photobiology B: Biology

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Three building blocks of the antenna complexes of the cyanobacterium Westiellopsis prolifica were studied: PEC(X), which is similar to the ot-subunit of phycoerythrocyanin (PEC), trimers of PEC and monomers derived from these by deaggregation with KSCN. The fit of the fluorescence decay curve of PEC(X) requires at least four exponentials, although it supposedly contains only one chromophore. The coherent anti-Stokes Raman scattering (CARS) spectra indicate that the heterogeneity observed is due to geometrical isomers, which are in part generated by photoinduced processes. A similar heterogeneity in chromophore structure and properties is also found in the monomers, where four exponentials are needed to fit the fluorescence decay curve. As in trimers, there is a long-lived, low-amplitude component, which can be assigned to impurities and/or oxidation products. The energy transfer time between the two phyocyanobilin chromophores in the/3-subunit is about 500 ps; the lifetime of the fluorescing /3-chromophore is 1.5 ns. The phycoviolobilin chromophore in the a-subunit adopts different geometries characterized by fluorescence liftetimes of about 240 and 800 ps. No evidence was found for energy transfer between the otehromophore and the /3-chromophores. This energy transfer occurs in trimers on a time scale of less than 20 ps; the energy transfer time between the two different types of/3-chromophore is about 250 ps and the lifetime of the terminal emitter is about 1.5 ns. The excited state kinetics are therefore similar to those of PEC trimers from Mastigocladus laminosus, as are the CARS spectra, indicating a similar chromophore-protein arrangement. In comparison with phycocyanin, the ordering of the excited states of chromophores fl84 and/3155 may be changed. Although PEC trimers of IVestiellopsis prolifica show almost as good a photostability as trimers of Mastigocladus laminosus, monomers are so photolabile that no CARS spectra could be recorded.

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Section: Introductionmentioning

confidence: 92%

“…2 and 3. They have been discussed in detail previously [9], and therefore we only need to summarize those features which are essential \\~\ \\\\ ~.…”

Section: Absorption and Stationary Fluorescencementioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Photophysics of phycoerythrocyanins from the cyanobacterium Westiellopsis prolifica studied by time-resolved fluorescence and coherent anti-Stokes Raman scattering spectroscopy

Schneider¹,

Jäger²,

Prenzel³

et al. 1994

Journal of Photochemistry and Photobiology B: Biology

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“…Recent studies gave increasing evidence for a basic similarity of this type I photochemistry with that of the plant sensory photoreceptor, phytochrome. Both involve the 15Z/E-isomerization of the bilin chromophore (Zhao et al, 1995), and the optical properties (absorption, fluorescence, circular dichroism) are largely comparable (Maruthi Sai et al, 1993). PEC and other biliproteins have also been implicated in photomorphogenesis of cyanobacteria (Kufer and Bjoern, 1989; Maruthi- Sai et al, 1992, Braune et al, 1988, but direct proof for this is still lacking.…”

Section: Introductionmentioning

confidence: 99%

Intermediates of reversible photochemistry of phycoerythrocyanin α from Mastigocladuslaminosus probed by low temperature absorptionand circular dichroism spectroscopy

Zhao

Scheer²

1999

International Journal of Photoenergy

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Abstract. The reversible photochemistry of the α-subunit of phycoerythrocyanin (α-PEC) has been measured by low temperature absorption and circular dichroism in the range of 125 K to 295 K. Below 185 K, the photochemistry is nearly silent; above 205 K, the photochemistry increases gradually without an indication of intermediates, and between 185 to 205 K spectral changes in absorption and circular dichroism indicate an intermediate and/or changes in the interaction(s) between the chromophore and its environment.

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Cyanobacterial Phycobilisomes

MacColl

1998

Journal of Structural Biology

581

442

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Cyanobacterial phycobilisomes harvest light and cause energy migration usually toward photosystem II reaction centers. Energy transfer from phycobilisomes directly to photosystem I may occur under certain light conditions. The phycobilisomes are highly organized complexes of various biliproteins and linker polypeptides. Phycobilisomes are composed of rods and a core. The biliproteins have their bilins (chromophores) arranged to produce rapid and directional energy migration through the phycobilisomes and to chlorophyll a in the thylakoid membrane. The modulation of the energy levels of the four chemically different bilins by a variety of influences produces more efficient light harvesting and energy migration. Acclimation of cyanobacterial phycobilisomes to growth light by complementary chromatic adaptation is a complex process that changes the ratio of phycocyanin to phycoerythrin in rods of certain phycobilisomes to improve light harvesting in changing habitats. The linkers govern the assembly of the biliproteins into phycobilisomes, and, even if colorless, in certain cases they have been shown to improve the energy migration process. The Lcm polypeptide has several functions, including the linker function of determining the organization of the phycobilisome cores. Details of how linkers perform their tasks are still topics of interest. The transfer of excitation energy from bilin to bilin is considered, particularly for monomers and trimers of C-phycocyanin, phycoerythrocyanin, and allophycocyanin. Phycobilisomes are one of the ways cyanobacteria thrive in varying and sometimes extreme habitats. Various biliprotein properties perhaps not related to photosynthesis are considered: the photoreversibility of phycoviolobilin, biophysical studies, and biliproteins in evolution. Copyright 1998 Academic Press.

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Fluorescence and Circular Dichroism Studies on the Phycoerythrocyanins From the Cyanobacterium

Cited by 17 publications

References 20 publications

Photophysics of phycoerythrocyanins from the cyanobacterium Westiellopsis prolifica studied by time-resolved fluorescence and coherent anti-Stokes Raman scattering spectroscopy

Photophysics of phycoerythrocyanins from the cyanobacterium Westiellopsis prolifica studied by time-resolved fluorescence and coherent anti-Stokes Raman scattering spectroscopy

Intermediates of reversible photochemistry of phycoerythrocyanin α from Mastigocladuslaminosus probed by low temperature absorptionand circular dichroism spectroscopy

Cyanobacterial Phycobilisomes

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