Chromatic adaptation in a mutant of Fremyella diplosiphon incapable of phycoerythrin synthesis

Beguin, Simone; Guglielmi, Gérard; Rippka, Rosmarie; Cohen-Bazire, Germaine

doi:10.1016/s0300-9084(85)80236-4

Cited by 18 publications

(8 citation statements)

References 22 publications

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“…5C). A similar observation was made earlier by Beguin et al (2), where induction of PXB chromophore under green light occurred in a mutant of Fremyella diplosiphon lacking PE, and this chromophore was also associated with a subunits of PC.…”

Section: Discussionsupporting

confidence: 87%

“…It may be hypothesized that in green light some kind of structural changes occur in some of the native apoproteins of PC which in turn are exposed to isomerases responsible for the transformation of PCB chromophores into PXB chromophores. These kinds of changes were suggested earlier by Glazer (16) and Beguin et al (2). Further, the presence of both 590 and 615 nm absorbing bands on the a subunits of PC and from the fact that a subunits of phycobiliproteins carry only one chromophore (15), it is quite possible that in this cyanobacterium S. platensis, some of the a subunit polypeptides of PC carry PCB chromophores and the others PXB chromophores.…”

Section: Discussionsupporting

confidence: 58%

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Effect of Light Quality on Phycobilisome Components of the Cyanobacterium Spirulina platensis

Babu¹,

Kumar²,

Varma³

1991

Plant Physiol.

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Phycobilisomes from the nonchromatic adapting cyanobacterium Spirulina platensis are composed of a central core containing allophycocyanin and rods with phycocyanin and linker polypeptides in a regular array. Room temperature absorption spectra of phycobilisomes from this organism indicated the presence of phycocyanin and allophycocyanin. However, low temperature absorption spectra showed the association of a phycobiliviolin type of chromophore within phycobilisomes. This chromophore had an absorption maximum at 590 nanometers when phycobilisomes were suspended in 0.75 molar K-phosphate buffer (pH 7.0). Purified phycocyanin from this cyanobacterium, was found to consist of three subparticles and the phycobiliviolin type of chromophore was associated with the lowest density subparticle. Circular dichroism spectra of phycocyanin subparticles also indicated the association of this chromophore with the lowest density subparticle. Absorption spectral analysis of a and ,B subunits of phycocyanin showed that phycobiliviolin type of chromophore was attached to the a subunit, but not the ,B subunit. Effect of light quality showed that green light enhanced the synthesis of this chromophore as analyzed from the room temperature absorption spectra of phycocyanin subparticles and subunits, while red or white light did not have any effect. Low temperature absorption spectra of phycobilisomes isolated from green, red, and white light conditions also indicated the enhancement of phycobiliviolin type of chromophore under green light.nm (14,22 (3,10,11,13).The present communication describes the effect of light quality on the synthesis and regulation of phycobiliproteins in the nonchromatic adapting cyanobacterium Spirulina platensis. We report here the presence of a PXB type of chromophore in this cyanobacterium and modulation in its level in response to the light quality. MATERIALS AND METHODS OrganismThe cyanobacterium Spirulina platensis was obtained from the Microbiology Division, Indian Agricultural Research Institute, New Delhi, India. Culture ConditionsPhycobiliproteins are the major accessory light harvesting pigments present in cyanobacteria, red algae, and cryptomonads. These proteins are broadly classified into three groups based on the spectroscopic properties: PE,2 Xmax, 540-570 nm; PC, Xmax, 610-620 nm; and APC, Xmax,650-655 nm (12,14). A few cyanobacteria possess a fourth type of biliprotein, PEC, Xmax, 568 nm, 585 nm(s) in place of PE (7). Each of these phycobiliproteins are comprised of two subunits, a and p3, to which linear tetrapyrroles are covalently attached by a cysteine thioether bond (15). The absorption characteristics of these tetrapyrroles in acidic aqueous solutions group them into four types: PCB, Xmax, 660 nm; PXB, Xmax, 590 nm; phycoerythrobilin Xmax, 555 nm; and phycourobilin Amax, 495

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Section: Discussionsupporting

confidence: 87%

Section: Discussionsupporting

confidence: 58%

Effect of Light Quality on Phycobilisome Components of the Cyanobacterium Spirulina platensis

Babu¹,

Kumar²,

Varma³

1991

Plant Physiol.

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“…An alternative approach to the understanding of these regulatory mechanisms is the use of mutants impaired in complementary chromatic adaptation. Such mutants have been isolated from Calothrix PCC 7601 and from Synechocystis PCC 6701 [89,105,[107][108][109]. However, unravelling the complexity of the pleiotropic phenotypes usually obtained by classical mutagenesis is a real challenge.…”

Section: Complementary Chromatic Adaptationmentioning

confidence: 99%

Adaptation of cyanobacteria to environmental stimuli: new steps towards molecular mechanisms

Marsac

Houmard

1993

FEMS Microbiology Letters

371

128

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Dating from the Pre‐Cambrian era, cyanobacteria have a long history of adaptation to the Earth's environment. By evolving oxygen via photosynthetic reactions similar to those of plants and green algae, these prokaryotes were essential to the evolution of the present biosphere. They continue to make a large contribution to the equilibrium of the Earth's atmosphere by production oxygen and removing carbon dioxide. To survive in extreme or variable environments, cyanobacteria have developed specific regulatory systems, in addition to more general mechanisms equivalent to those of other prokaryotes or photosynthesis eukaryotes. Specific regulatory systems control the differentiation of specialized nitrogen‐fixing cells and of cell types facilitating the dispersion of species. In the past decade, considerable progress has been made towards understanding the expression of the cyanobacterial genome in response to variations in the intensity and spectral quality of incident light and in response to nutritional conditions, especially carbon, nitrogen and sulphur sources. These studies have provided insights into the relationships between carbon and nitrogen intermediary metabolism, and a start towards understanding of the interconnected pathways which lead from the perception of environmental signals to the regulation of enzyme activities and gene expression. Cyanobacterial regulatory mechanisms share common features with those of other prokaryotes, but are unique since these essentially photo‐autotrophic organisms must maintain a proper cellular C/N balance, in spite of dailty variations in incident light. Thus an appropriate coordination between photosynthesis and other metabolic processes must be achieved through control of the catalytic activity of key enzymes by reducing equivalents and ATP produced by photosynthetic or respiratory electron transport. Recently discovered kinases/phosphatases act by post‐translational modification of specific proteins which probably act as signal transducers or modulators of gene expression in a manner similar to the well‐known two‐component regulatory systems described in other bacteria. In this overview, we present our current knowledge on the molecular aspects of the biology of cyanobacteria, as well as on their mechanisms of resistance to metal ions and their responses to metabolic stress.

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“…components have been isolated in cyanobacteria (3,5,12,39). Some of these arose spontaneously (35), whereas others were generated by UV light (3,12) or nitrosoguanidine (5) treatment.…”

mentioning

confidence: 99%

“…Some of these arose spontaneously (35), whereas others were generated by UV light (3,12) or nitrosoguanidine (5) treatment. We describe here three classes of pigment mutants of F. diplosiphon.…”

mentioning

confidence: 99%

Molecular characterization of phycobilisome regulatory mutants of Fremyella diplosiphon

1989

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Three classes of pigment mutants were generated in Fremyella diplosiphon in the course of electroporation experiments. The red mutant class had high levels of phycoerythrin in both red and green light and no inducible phycocyanin in red light. Thus, this mutant behaved as if it were always in green light, regardless of light conditions. Blue mutants exhibited normal phycoerythrin photoregulation, whereas the inducible phycocyanin was present at high levels in both red- and green-light-grown cells. Furthermore, the absolute amount of allophycocyanin was increased threefold in comparison with our wild-type strain. Green mutants lost the capacity to accumulate phycoerythrin in green light but showed normal photoregulation of phycocyanin. Analyses of transcript abundance in these mutants demonstrated that changes in the levels of the different phycobilisome components correlated with changes in the levels of mRNAs encoding those components. The characterization of these mutants supports hypotheses previously discussed concerning molecular mechanisms involved in the regulation of the phycobiliprotein gene sets during chromatic adaptation.

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Chromatic adaptation in a mutant of Fremyella diplosiphon incapable of phycoerythrin synthesis

Cited by 18 publications

References 22 publications

Effect of Light Quality on Phycobilisome Components of the Cyanobacterium Spirulina platensis

Effect of Light Quality on Phycobilisome Components of the Cyanobacterium Spirulina platensis

Adaptation of cyanobacteria to environmental stimuli: new steps towards molecular mechanisms

Molecular characterization of phycobilisome regulatory mutants of Fremyella diplosiphon

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