STUDIES ON PLANT BILE PIGMENTS. II. REGIOSELECTIVE PHOTOCHEMICAL AND ACID CATALYZED <i>Z,E</i> ISOMERIZATION OF DIHYDROBILINDIONE AS PHYTOCHROME MODEL

Kufer, Werner; Cmiel, Edmund; Thümmler, F.; Rüdiger, Wolfhart; Schneider, Siegfried; Scheer, Hugo

doi:10.1111/j.1751-1097.1982.tb04423.x

Cited by 25 publications

(24 citation statements)

References 30 publications

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“…The same properties as for the Pfr chromopeptide have been demonstrated for geometric isomers (E-configurated) prepared from all-Z-configurated Pr chromopeptides and phycocyanin chromopeptides (11). Similar properties also were reported for E-configurated bilindiones (12)(13)(14)(15)(16)(17). It was concluded that the chromophore of the Pfr peptide should be either the 15E (structure Ila) or the 4E (structure lila) compound (11).…”

supporting

confidence: 64%

Chromophore structure of the physiologically active form (P _fr ) of phytochrome

Rüdiger¹,

Thümmler²,

Cmiel

et al. 1983

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

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197

161

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Chromopeptides were prepared by proteolytic digestion of phytochrome (far-red absorbing form, Pfr) and of phycocyanin. The phycocyanobilin peptide, the chromophore of which is Z,Z,Z-configurated, was modified to the Z,ZE isomeric chromophore. It has been demonstrated earlier that the Pfr chromopeptide and the Z,Z,E-configurated phycocyanin chromopeptide behave similarly with regard to spectral and chromatographic properties and reactivity. We present evidence here, obtained by high-resolution 'H NMR spectroscopy, that both the modified phycocyanobilin chromophore and the phytochrome chromophore obtained directly from Pfr are 15E-configurated.Plant development is influenced by light in many ways. An important photoreceptor of higher plants is the chromoprotein phytochrome (1-3), which can mediate light-dependent irreversible differentiation (e.g., seed germination, flowering, and stem and leaf growth) and reversible modulations (e.g., leaflet or chloroplast movement, root tip adhesion, and transmembrane potentials).A characteristic property of phytochrome in vivo (in the plant cell) and in vitro is its photoreversibility. The physiologically inactive (red-absorbing) Pr form (Ama. = 660 nm) is transformed by red light to the physiologically active Pfr form (Amak = 730 nm), which in turn is reconverted by far-red light to the Pr form. nm Pr = Pfr 730 nmThe chemical structure of the Pr chromophore (structure la), including its linkage to the protein, was elucidated by combination of oxidative degradation and UV/visible spectroscopy (4-6), by comparison of the cleaved chromophore with the product obtained by total synthesis (7,8), and by high-resolution NMR spectroscopy of a chromopeptide (9). It is closely related to the structure of the phycocyanin chromophore

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supporting

confidence: 64%

Chromophore structure of the physiologically active form (P _fr ) of phytochrome

Rüdiger¹,

Thümmler²,

Cmiel

et al. 1983

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

Self Cite

197

161

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“…7). Consistent with this hypothesis, neutral ZZE dihydrobilindiones have been reported to exhibit peak absorbance at wavelengths as short as 520 nm (64). The P g species thus could be a neutral ZZE isomer of PCB without any further modification.…”

Section: Discussionmentioning

confidence: 74%

“…7). Such an adduct would be expected to exhibit peak absorbance at approximately 420 nm (64)(65)(66), with a second transition arising from the A and B rings and giving peak absorbance at ∼358−366 nm in the isolated chromophore (66). This shorterwavelength transition would be further blue-shifted by the presence of the covalent linkage between Cys527 and the C3 1 carbon, explaining the 336 nm band of P b S .…”

Section: Discussionmentioning

confidence: 99%

A Second Conserved GAF Domain Cysteine Is Required for the Blue/Green Photoreversibility of Cyanobacteriochrome Tlr0924 from Thermosynechococcus elongatus

et al. 2008

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Phytochromes are widely occurring red/far-red photoreceptors that utilize a linear tetrapyrrole (bilin) chromophore covalently bound within a knotted PAS-GAF domain pair. Cyanobacteria also contain more distant relatives of phytochromes that lack this knot, such as the phytochrome-related cyanobacteriochromes implicated to function as blue/green switchable photoreceptors. In this study, we characterize the cyanobacteriochrome Tlr0924 from the thermophilic cyanobacterium Thermosynechococcus elongatus. Full-length Tlr0924 exhibits blue/green photoconversion across a broad range of temperatures, including physiologically relevant temperatures for this organism. Spectroscopic characterization of Tlr0924 demonstrates that its green-absorbing state is in equilibrium with a labile, spectrally distinct blue-absorbing species. The photochemically generated blue-absorbing state is in equilibrium with another species absorbing at longer wavelengths, giving a total of 4 states. Cys499 is essential for this behavior, because mutagenesis of this residue results in red-absorbing mutant biliproteins. Characterization of the C 499 D mutant protein by absorbance and CD spectroscopy supports the conclusion that its bilin chromophore adopts a similar conformation to the red-light-absorbing P r form of phytochrome. We propose a model photocycle in which Z/E photoisomerization of the 15/16 bond modulates formation of a reversible thioether linkage between Cys499 and C10 of the chromophore, providing the basis for the blue/green switching of cyanobacteriochromes.Photosynthetic organisms face the need to coordinate their metabolic responses to their light environment, so that photosynthesis and redox balance are properly maintained for growth. This is accomplished by a wide range of photosensory proteins (1,2). The first such proteins to be discovered were the phytochromes, which are red/far-red photosensors initially described in plants and later shown to be widespread in both photosynthetic and nonphotosynthetic organisms (3,4). Upon excitation with red light, phytochromes photoconvert from the redabsorbing P r state 1 , which is usually thermally stable, to the far-red absorbing P fr state (5). This reversible interconversion is the result of light-driven Z/E isomerization of the 15/16 double bond of the protein-bound bilin chromophore ( Fig. 1), which is covalently attached to a Cys residue in the conserved photosensory core of phytochromes. This photosensory core is generally found N-terminal to putative output domains implicated in signal transduction, such as the histidine kinase domain of the cyanobacterial phytochrome Cph1 (6). Since both P r and NIH Public Access Author ManuscriptBiochemistry. Author manuscript; available in PMC 2009 July 8. Published in final edited form as:Biochemistry. 2008 July 8; 47(27): 7304-7316. doi:10.1021/bi800088t. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript P fr states can generate signaling outputs (4,7), light modulates the signaling activity of phytochrome...

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“…PCB can undergo rotational isomerization about its three methine bridges and the 3-ethylidene double bond; the predominant isomer in solution is all-Z, syn at the bridges, but a minor fraction of a "stretched" form with distinct absorbance and fluorescence spectra has been detected and attributed to E isomers at the central, C-10 bridge (21). E,Z,Z and Z,Z,E isomers (at the C-5, C-10, C-15 methine bridges) of related bilatrienes can be formed that are stable at room temperature (22)(23)(24). The isomer of PCB adduct found on holo-a'c has been determined to be Z-anti, Z-syn, Z-anti (25).…”

Section: Resultsmentioning

confidence: 98%

Phycocyanin alpha-subunit phycocyanobilin lyase.

Fairchild

Zhao

Zhou

et al. 1992

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

143

121

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Phycobiliproteins, unlike other light-harvesthmg proteins involved in photosynthesis, bear covalently attached chromophores. The bilin chromophores are attached through thioether bonds to cysteine residues. The cyanobacterium Synechococcus sp. PCC 7002 has eight distinct blin attachmnt sites on seven poypeptides, all ofwhich carry the same chromophore, phycocyanobilin. When two genes in the phycocyanin operon of this organisn, cpcE and cpcF, are inactivated by insertion, together or separately, the srping result is elimination of correct biln attachment at only one site, that on the a subunit of phycocyanin. We have overproduced CpcE and CpcF in Escherichia coli. In vitro, these proteins catalyze the attachment of phycocyanobilin to the a subunit of apophycocyanin at the appropriate site, a-Cys-84, to form the correct adduct. CpcE and CpcF also efficiently catalyze the reverse reaction, in which the bilin from holo-a subunit is transferred either to the apo-a subunit of the same C-phycocyanin or to the apo-a subunit of a heterologous C-phycocyanin. The forward and reverse reactions each require both CpcE and CpcF and are specific for the a-Cys-84 position. Phycocyanobilin is the immediate precursor of the protein-bound bilin.Phycobiliproteins are homologous proteins found in cyanobacteria, red algae, and the cryptomonads (1). In vivo they form highly ordered macromolecular light-harvesting assemblies, phycobilisomes, in which directional energy transfer is determined by the spectroscopic properties and relative positions of the bilin prosthetic groups.The number of bilin attachment sites on all of the phycobiliproteins ofa particular cyanobacterium or red alga ranges from a minimum of 8, all carrying the same bilin, to >20, with up to three different bilins. To study the process of bilin attachment we have chosen a simple case, that in Synechococcus sp. PCC 7002, in which there are 8 attachment sites for the same bilin, phycocyanobilin (PCB), on seven polypeptides.Posttranslational modification of proteins usually involves recognition of simple amino acid sequence determinants. Local sequence homology around modification sites generally suggests that there is one enzyme that recognizes all of these sites. Surprisingly, this does not appear to be the case for bilin attachment to phycobiliproteins.Until recently little was known about the processes of bilin synthesis and attachment to the apoproteins. Beale and Comejo (2-4) have examined bilin biosynthesis in the red alga Cyanidium caldarium and have provided evidence for the following pathway: heme --biliverdin IXa -15,16-dihydrobiliverdin IXa -. 3(Z)-phycoerythrobilin -3(Z)-PCB -+ 3(E)-PCB.PCB can be obtained by cleavage from phycocyanin or allophycocyanin by methanolysis (5). PCB has an ethylidene group at the C-3 position (the IUPAC numbering system for bilins is shown for PCB in ref. 2) and is the product of elimination of cysteine at the 3' carbon of the protein-bound bilin (3,3'-dihydro-3'-cysteinylphycocyanobilin; referred to below as PCB adduct).T...

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STUDIES ON PLANT BILE PIGMENTS. II. REGIOSELECTIVE PHOTOCHEMICAL AND ACID CATALYZED Z,E ISOMERIZATION OF DIHYDROBILINDIONE AS PHYTOCHROME MODEL

Cited by 25 publications

References 30 publications

Chromophore structure of the physiologically active form (P _fr ) of phytochrome

Chromophore structure of the physiologically active form (P _fr ) of phytochrome

A Second Conserved GAF Domain Cysteine Is Required for the Blue/Green Photoreversibility of Cyanobacteriochrome Tlr0924 from Thermosynechococcus elongatus

Phycocyanin alpha-subunit phycocyanobilin lyase.

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STUDIES ON PLANT BILE PIGMENTS. II. REGIOSELECTIVE PHOTOCHEMICAL AND ACID CATALYZED Z,E ISOMERIZATION OF DIHYDROBILINDIONE AS PHYTOCHROME MODEL

Cited by 25 publications

References 30 publications

Chromophore structure of the physiologically active form (P fr ) of phytochrome

Chromophore structure of the physiologically active form (P fr ) of phytochrome

A Second Conserved GAF Domain Cysteine Is Required for the Blue/Green Photoreversibility of Cyanobacteriochrome Tlr0924 from Thermosynechococcus elongatus

Phycocyanin alpha-subunit phycocyanobilin lyase.

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Product

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Chromophore structure of the physiologically active form (P _fr ) of phytochrome

Chromophore structure of the physiologically active form (P _fr ) of phytochrome