Experimental evidence of oligomeric organization of antenna bacteriochlorophyll <i>c</i> in green bacterium <i>Chloroflexus aurantiacus</i> by spectral hole burning

Fetisova, Z. G.; Mauring, Koit

doi:10.1016/0014-5793(92)80715-s

Cited by 57 publications

(54 citation statements)

References 11 publications

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“…We observed that the CD intensity of low-light chlorosomes only doubled upon treatment with proteinase K compared to a fivefold increase in the high-light chlorosomes. There is some evidence that BChl c in the chlorosome is organized as oligomers [8,9], which may be bound to protein in order to maintain parallel transition moments between clusters of BChl c [2.5,26]. There are several reports that BChl c aggregates in hexane [27,28], in aqueous suspension, or after LDS treatment [4], and after proteolytic treatment [4,18] exhibited higher rotational strength than BChl c in chlorosomes of ChlorojZexus auruntiucus.…”

Section: Discussionmentioning

confidence: 99%

Structural differences in chlorosomes from Chloroflexus aurantiacus grown under different conditions support the BChl c‐binding function of the 5.7 kDa polypeptide

1994

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Structurally different chlorosomes were isolated from the green photosynthetic bacterium Chloroflexus aurantiacus grown under different conditions. They were analysed with respect to variable pigment-protein stoichiometries in view of the presumed BChl c-binding function of the 5.7 kDa chlorosome polypeptide. Under high-light conditions on substrate-limited growth medium the pigment-protein ratio of isolated chlorosomes was several times lower than under low-light conditions on complex medium. Proteolytic degradation of the 5.7 kDa polypeptide in high-light chlorosomes led to a 60% decrease of the absorbance at 740 nm. The CD spectrum of high-light chlorosomes exhibited a sixfold lower relative intensity at 740 nm (AA/&,,) than low-light chlorosomes, but it showed a fivefold increase in intensity upon degradation of the 5.7 kDa polypeptide compared to a twofold increase in low-light chlorosomes. It seems probable that BChl c in the chlorosomes is present as oligomers bound to the 5.7 kDa polypeptide. Our data suggest further that compared to low-light chlorosomes smaller oligomers or single BChl c molecules are bound to the 5.7 kDa polypeptide in high-light chlorosomes resulting in lower rotational strength.

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Section: Discussionmentioning

confidence: 99%

Structural differences in chlorosomes from Chloroflexus aurantiacus grown under different conditions support the BChl c‐binding function of the 5.7 kDa polypeptide

1994

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“…Using the standard approach to the exciton-phonon problem in molecular crystals, we discovered that none of the earlier proposed models of BChl aggregation in chlorosomal antennae displays the in vivo exciton level structure of a BChl aggregate revealed by hole burning experiments on intact cells of different green bacteria [7][8][9].…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, experimental hole burning spectra of chlorosomal antennae of green bacteria show a broad absorption spectrum due to many electronic (exciton) levels. The higher levels have ,-~ 98% of the total oscillator strength [7][8][9].…”

Section: Resultsmentioning

confidence: 99%

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Antenna size dependent exciton dynamics in the chlorosomal antenna of the green bacterium Chloroflexus aurantiacus

Fetisova¹,

Freiberg²,

Novoderezhkin³

et al. 1996

FEBS Letters

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aldehyde, postfixed with OsO4, embedded in Epon-812, and ultrathinsectioned by standard method [4]. Micrographs of the ultrathin sections were used for morphometric measurements (magnification 50 000 × 10) to obtain histograms of chlorosomes heights and calculate the number of layers of rod elements in the chlorosome, assuming that the diameter of the rod equals 5.5 nm [4,5].Absorption spectra of intact cells were recorded with a Hitachi-557 spectrophotometer (Japan).Spectrally resolved fluorescence measurements for intact cells of C aurantiacus were made with a picosecond spectrochronograph [6]. The pulse source was a mode-locked CW rhodamine 590 dye laser (pulse duration, 3 ps), synchronously pumped at 76 MHz by a NdYag laser (Ontares, 'Coherent'). Emission, viewed at an angle of 90 ° to the exciting beam, was registered with a home-made synchroscan streak camera. The time resolution of the measuring system was 10 ps.

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“…One of the structural optlmizlng factors is oligomerization of antenna pigments [2). The chlorosome of green bacteria contalning several thousands of antenna bacteriochlorophyll (BChl) c,d or e molecules in an aggregated state is the most convincing example of natural antenna of oligomeric type (3)(4)(5). The discovered strong orientational ordering of the near-infrared transition dipoles of BChl c in situ (6) suggested that an elementary BChl aggregate has the form of a linear chain.…”

Section: Introductionmentioning

confidence: 99%

Structure of bacteriochlorophyll aggregates in chlorosomes of green bacteria: A spectral hole burning study

Novoderezhkin

Fetisova

1996

IUBMB Life

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SUMMARY.Exclton level structure, homogeneous absorption and hole-burning spectra were calculated for different models of bacteriochlorophyll aggregation in chlorosomal antennae of green bacteria. It was demonstrated that none of the earlier proposed models of noninteracting linear bacterlochlorophyll aggregates and linear bacterlochlorophyll chains assembling in tubular aggregates with high density of packing, exhibits the in vivo exclton level structure revealed by hole-burnlng experiments on intact cells of green bacteria. The models of linear exciton-coupled bacteriochlorophyll chains with a low packin E density, approximating that in vlvo, were proposed as alternative, to obtain the main spectral features found in natural antennae.

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Experimental evidence of oligomeric organization of antenna bacteriochlorophyll c in green bacterium Chloroflexus aurantiacus by spectral hole burning

Cited by 57 publications

References 11 publications

Structural differences in chlorosomes from Chloroflexus aurantiacus grown under different conditions support the BChl c‐binding function of the 5.7 kDa polypeptide

Structural differences in chlorosomes from Chloroflexus aurantiacus grown under different conditions support the BChl c‐binding function of the 5.7 kDa polypeptide

Antenna size dependent exciton dynamics in the chlorosomal antenna of the green bacterium Chloroflexus aurantiacus

Structure of bacteriochlorophyll aggregates in chlorosomes of green bacteria: A spectral hole burning study

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