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Frigaard, Niels‐Ulrik; Matsuura, Kiyotaka; Hirota, Masamitsu; Miller, Megan; Cox, Raymond P.

doi:10.1023/a:1006043706652

Cited by 40 publications

(21 citation statements)

References 32 publications

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“…The HPLC analysis showed that untreated chlorosomes from C. tepidum contained approximately one quinone per 8 BChl c, and the CK content was five times the MK-7 content ( Table 1). These values agree with our previous results (17). In contrast, chlorosomes from C. phaeobacteroides contained about equal amounts of CK and MK-7, with a total BChl elquinone ratio of 14 (Table 1).…”

Section: Effects On Chlorosome Componentssupporting

confidence: 92%

“…Samples were extracted in a twophase system consisting of aqueous medium : methanol : chloroform (2:2:1 by volume). The chloroform phase was withdrawn and vacuum dried and the dried extract analyzed by reverse-phase HPLC as previously described (17). The BChl a to BChl c or e ratio was determined by absorption spectroscopy by injecting a small volume of the chloroform phase of the chlorosome extract into methanol (17).…”

Section: Methodsmentioning

confidence: 99%

“…The chloroform phase was withdrawn and vacuum dried and the dried extract analyzed by reverse-phase HPLC as previously described (17). The BChl a to BChl c or e ratio was determined by absorption spectroscopy by injecting a small volume of the chloroform phase of the chlorosome extract into methanol (17). The absorption coefficient of BChl e at the Q, band in methanol (28 mM-~' cm-' at 663 nm) was estimated from the corresponding value in acetone (19) by comparing the absorption of an extract of C. phaeobacteroides chlorosomes in methanol and acetone.…”

Section: Methodsmentioning

confidence: 99%

“…A stronger fluorescence emission is observed under reducing (anoxic) conditions corresponding to longer lifetimes of the BChl excited state: values between 40 ps and 66 ps have been reported (14)(15)(16). Recently it was found that isolated chlorosomes from the green sulfur bacterium Chlorobium tepidum contain chlorobiumquinone (CK) and menaquinone-7 (MK-7) in a total concentration of approximately 0.1 mol per mol BChl and it was suggested these may participate in the redox-dependent control of EET (17).…”

Section: Introductionmentioning

confidence: 99%

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Effect of Alkaline Treatment on Bacteriochlorophyll a, Quinones and Energy Transfer in Chlorosomes from Chlorobium tepidum and Chlorobium phaeobacteroides

Walree

Sakuragi

Steensgaard

et al. 1999

Photochem & Photobiology

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Chlorosomes isolated from two types of green sulfur bacteria, Chlorobium tepidum which contains bacteriochlorophyll c (BChl c ) and the BChl e-containing Chlorobium phaeobacteroides, were subjected to alkaline treatment (pH 12.7 at 40°C for 20 min). This caused selective degradation of BChl a, whereas BChl c or e were not affected. Chlorobiumquinone in the chlorosomes was partially degraded by the alkaline treatment but menaquinone was unchanged. Fluorescence decay kinetics showed that alkaline treatment disrupted energy transfer from BChl c or e to BChl a under reducing conditions. However, this did not give rise to any substantial increase in the excited state lifetime of BChl e in C. phaeobacteroides chlorosomes, while for C. tepidum a decrease in the BChl c lifetime was found. The steady-state fluorescence of chlorosomes is highly dependent on the redox potential such that emission is quenched in oxidizing environments. Alkaline treatment diminished this quenching effect and caused a doubling in the BChl c or e emission intensity under aerobic conditions. Single-photon timing experiments confirmed that alkaline treatment inhibits the energy trapping process operative under aerobic conditions. These effects of alkaline treatment on the fluorescence intensity and decay kinetics are likely to be related to the depletion in BChl a or in chlorobiumquinone or a combination of these.

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Section: Effects On Chlorosome Componentssupporting

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Alkaline Treatment on Bacteriochlorophyll a, Quinones and Energy Transfer in Chlorosomes from Chlorobium tepidum and Chlorobium phaeobacteroides

Walree

Sakuragi

Steensgaard

et al. 1999

Photochem & Photobiology

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“…Possible candidates include the multiple homologs of CrtD͞CrtI (CT0649, CT0807, CT1414, and CT0180). C. tepidum synthesizes two major quinones, menaquinone-7 and chlorobiumquinone (58). Homologs of all enzymes for the conversion of chorismate into menaquinone in E. coli (59) were identified.…”

Section: Resultsmentioning

confidence: 99%

The complete genome sequence of Chlorobium tepidum TLS, a photosynthetic, anaerobic, green-sulfur bacterium

Eisen

Nelson

Paulsen

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

347

303

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The complete genome of the green-sulfur eubacterium Chlorobium tepidum TLS was determined to be a single circular chromosome of 2,154,946 bp. This represents the first genome sequence from the phylum Chlorobia, whose members perform anoxygenic photosynthesis by the reductive tricarboxylic acid cycle. Genome comparisons have identified genes in C. tepidum that are highly conserved among photosynthetic species. Many of these have no assigned function and may play novel roles in photosynthesis or photobiology. Phylogenomic analysis reveals likely duplications of genes involved in biosynthetic pathways for photosynthesis and the metabolism of sulfur and nitrogen as well as strong similarities between metabolic processes in C. tepidum and many Archaeal species.

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