Differences in the control of bacteriochlorophyll formation by light and oxygen

Arnheim, Katharina; Oelze, J.

doi:10.1007/bf00413485

Cited by 25 publications

(12 citation statements)

References 18 publications

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“…No such differences could be registered with respect to the control of both complexes by light. Moreover, the data confirm observations of different types of kinetics underlying the control of bacteriochlorophyll synthesis by oxygen and light [3]. Investigations on the molecular basis for the observed differences of control are in progress.…”

Section: Discussionsupporting

confidence: 77%

“…(ATCC no. 17023) was grown in continuous culture at 30°C and pH 7.0 with automatic pH and pOz measure and control devices (Biostat S, B. Braun, Melsungen). The ~02 meter was calibrated with air and, therefore, relative oxygen concentrations are given as percent air saturation of the culture medium [3]. The complex growth medium R8AH [4] with 1.5 g malate/ and 0.5 g yeast extract/l, was added at a dilution rate of D = 0.109 h-r. Phototrophic conditions were established by illuminating the cultures with white incandescent light as in section 3.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, investigations on the control of both of the pigment-protein complexes by light have to be performed with cells of relatively low initial bacteriochlorophyll contents. This is conveniently achieved by growing cultures at an appropriately low constant oxygen concentration and different light energy fluxes [3]. Here, oxygen of 1% air saturation allowed the simultaneous study of the control of both complexes by light.…”

Section: R~odopseudom~~as Sphaeroides Was Grown Atmentioning

confidence: 99%

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Control by light and oxygen of B875 and B850 pigment‐protein complexes in Rhodopseudomonas sphaeroides

Arnheim

Oelze

1983

FEBS Letters

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Control by light and oxygen of the formation of B875 and 13850 pigment-protein complexes in ~hodopse~domon~s sphueroides was evaluated by use of Hill plots. Kinetics of oxygen-de~ndent control exhibited Hill coefficients of n = 1.06 and n = 0.65 for B875 and 8850 complexes, respectively. Halfmaximum inhibition of B875 complexes was at 20.4% air saturation of the medium and of B850 complexes at 0.9%. Light controlled both complexes with an identical sigmoidal kinetics of n = 2.1. Phototrophic bacteria Rhodopseudomonas sphaeroides Pigment complex Oxygen-dependent controlLight-dependent control

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Section: Discussionsupporting

confidence: 77%

Section: Methodsmentioning

confidence: 99%

Section: R~odopseudom~~as Sphaeroides Was Grown Atmentioning

confidence: 99%

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Control by light and oxygen of B875 and B850 pigment‐protein complexes in Rhodopseudomonas sphaeroides

Arnheim

Oelze

1983

FEBS Letters

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“…Most of the attention has been devoted to regulation by oxygen tension (6,8,15,39), light intensity (1,5,23), DNA supercoiling (40), and the effects of the recently discovered pufQ gene (3,16). Relatively little attention has been paid to the interrelationships between heme and bacteriochlorophyll syntheses.…”

Section: Discussionmentioning

confidence: 99%

Isolation of a Rhodobacter capsulatus mutant that lacks c-type cytochromes and excretes porphyrins

Biel

1990

J Bacteriol

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A Rhodobacter capsulatus mutant lacking cytochrome oxidase activity was isolated by TnS mutagenesis. Difference spectroscopy of crude extracts and extracted c-type cytochromes demonstrated that this mutant completely lacked all c-type cytochromes. The strain did, however, synthesize normal amounts of b-type cytochromes and nonheme iron. This mutant also excreted large amounts of coproporphyrin and protoporphyrin and synthesized reduced amounts of bacteriochlorophyll, suggesting a link between the synthesis of c-type cytochromes and the expression of the tetrapyrrole biosynthetic pathway.The photosynthetic bacterium Rhodobacter capsulatus uses a single branched pathway to synthesize two major tetrapyrrole end products, heme and bacteriochlorophyll, and two minor tetrapyrrole end products, siroheme and vitamin B12. Since bacteriochlorophyll levels vary greatly with growth conditions, whereas heme levels remain relatively constant, some mechanism must exist to monitor and independently control the levels of these two tetrapyrroles. Studies in Rhodobacter sphaeroides have suggested that carbon flow over the common tetrapyrrole pathway leading to protoporphyrin is controlled by heme (25), and that heme may feedback inhibit aminolevulinate synthase (36). Recently, there have been some intriguing observations suggesting a link between cytochrome synthesis and pigment formation. Mutants lacking the R. capsulatus cytochrome be complex showed increased pigmentation (12), whereas mutants with reduced capacity to synthesize c-type cytochromes excreted an uncharacterized pigment (17). These observations suggest that the regulation of these two branches may be more complicated than previously thought. We attempted to probe the possible link between cytochrome c biosynthesis and expression of the tetrapyrrole pathway by isolating a mutant that completely lacks c-type cytochromes. Several years ago an R. capsulatus strain, MT113, was isolated (38) and subsequently shown to have reduced levels of all c-type cytochromes (13). This strain was isolated during a screen for normally pigmented mutants that lack cytochrome oxidase activity (38). In this report we describe the use of the cytochrome oxidase assay to isolate a TnS insertion mutant that completely lacks c-type cytochromes. In addition to lacking c-type cytochromes, this strain excretes coproporphyrin and protoporphyrin and synthesizes reduced amounts of bacteriochlorophyll. The isolation of this strain and the cloning of the gene responsible for the pleotropic phenotype will allow us to investigate the connection between cytochrome c synthesis and the expression of the tetrapyrrole biosynthetic pathway. sulfoxide. Escherichia coli was grown in L broth (4), which was modified by omitting glucose and decreasing the sodium chloride concentration to 0.5%. Solid media contained 1.5% agar (Difco). Antibiotics, when necessary, were added at the following final concentrations: kanamycin, 10 ,ug/ml; tetracycline, 1 pug/ml; spectinomycin, 5 ,ug/ml. Pigment determinations. Porphyrins...

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“…Early studies by Cohen-Bazire et al (12) demonstrated that oxygen represses bacteriochlorophyll biosynthesis in purple nonsulfur photosynthetic bacteria. The control of bacteriochlorophyll formation by both oxygen and light has also been described (1,2,27). The transcription of several genes for bacteriochlorophyll biosynthesis in R. capsulatus has been shown to be regulated by oxygen (4).…”

mentioning

confidence: 99%

Oxygen-regulated mRNAs for light-harvesting and reaction center complexes and for bacteriochlorophyll and carotenoid biosynthesis in Rhodobacter capsulatus during the shift from anaerobic to aerobic growth

Zhu¹,

Cook²,

Leach³

et al. 1986

J Bacteriol

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The stability and regulation by oxygen of mRNAs for the photosynthetic apparatus in Rhodobacter capsulatus have been studied by using proflavin to inhibit transcription and by shifting cells from anaerobic to aerobic conditions. The results from the inhibition experiments show that the mRNA for the light-harvesting LH-II polypeptides (,, a) is more stable than that for the light-harvesting LH-I polypeptides (0, a) during anaerobic growth, whereas the mRNAs for the reaction center polypeptides L (RC-L), M (RC-M), and H (RC-H) are less stable than both the LH-I and LH-II mRNAs. When photosynthetic cells are shifted from anaerobic to aerobic conditions, an immediate decrease in the levels of mRNA for the LH-I, LH-II, RC-L, RC-M, and RC-H proteins was observed. The level of mRNA for the LH-II proteins, however, is more sensitive to oxygen and is reduced faster than the level of mRNA for the LH-I proteins. These results suggest that oxygen represses the expression of genes coding for the light-harvesting antenna and reaction center complexes and may selectively accelerate the degradation of mRNA for the LH-II proteins. The mRNAs for several enzymes in the bacterioclhlorophyll biosynthetic pathway are regulated by oxygen in a similar manner. The mRNAs for carotenoid biosynthetic enzymes, however, are regulated by oxygen in a different way. We have found that the amounts of mRNAs for carotenoid biosynthetic enzymes, relative to the amounts of mRNAs for LH and RC, increased during the shift from anaerobic to aerobic conditions. We have particularly shown that although the expression of most photosynthetic genes in R. capsulatus is repressed by oxygen, the crtA gene, located in the BamHI H fragment of the R' plasmid pRPS404 and responsible for the oxidation of spheroidene to spheroidenone, responds to oxygen in an opposite fashion. This enzymatic oxidation may protect the photosynthetic apparatus from photooxidative damage.Rhodobacter capsulatus (19), which normally inhabits muddy lake bottoms and sewage lagoons, is a gram-negative, facultative, photosynthetic bacterium. It can generate metabolic energy by either aerobic respiration or anaerobic photosynthesis depending on the oxygen concentration and light intensity in its environment. The photosynthetic apparatus is composed of pigment-protein complexes for the conversion of light to chemical energy, including a shortwavelength light-harvesting antenna, LH-II (also denoted B800-850 by its near-infrared absorption maxima), a longwavelength light-harvesting antenna, LH-I (also denoted B870), and a reaction center complex consisting of three polypeptides (RC-L, RC-M, and RC-H). Each of these complexes binds bacteriochlorophyll and carotenoid pigments. The photosynthetic apparatus contains additional electron transport proteins to complete the cyclic pathway of electron transport. A decrease in oxygen concentration induces formation of the photosynthetic apparatus, which is localized within invaginations of the cellular membrane known as the intracytoplasmic membrane (16,...

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Differences in the control of bacteriochlorophyll formation by light and oxygen

Cited by 25 publications

References 18 publications

Control by light and oxygen of B875 and B850 pigment‐protein complexes in Rhodopseudomonas sphaeroides

Control by light and oxygen of B875 and B850 pigment‐protein complexes in Rhodopseudomonas sphaeroides

Isolation of a Rhodobacter capsulatus mutant that lacks c-type cytochromes and excretes porphyrins

Oxygen-regulated mRNAs for light-harvesting and reaction center complexes and for bacteriochlorophyll and carotenoid biosynthesis in Rhodobacter capsulatus during the shift from anaerobic to aerobic growth

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