Absorption Spectra of Phytochrome Intermediates

Eilfeld, Peter; Rüdiger, Wolfhart

doi:10.1515/znc-1985-1-221

Cited by 100 publications

(82 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Subtracting the residual contribution of unphotolyzed P r , an absorption spectrum is obtained that is reminiscent of the Meta-R C state found in phyA ( Fig. 6) (25). The difference spectrum "intermediate minus P fr " reveals close similarities to the amplitude spectrum of the fourth relaxation component (B 4 ) obtained in the time-resolved measurements and an even better agreement is achieved for a mixture of 85% of B 4 and 15% of B 3 .…”

Section: Resultssupporting

confidence: 53%

“…The difference spectrum "intermediate minus P fr " reveals close similarities to the amplitude spectrum of the fourth relaxation component (B 4 ) obtained in the time-resolved measurements and an even better agreement is achieved for a mixture of 85% of B 4 and 15% of B 3 . Thus, the cryogenically trapped state mainly corresponds to the precursor of P fr and is, therefore, denoted as Meta-R C (Agp1) in analogy to the P fr precursor of phyA stabilized at the same temperature (25).…”

Section: Resultsmentioning

confidence: 99%

“…Also the number of the thermal chromophore relaxations and their decay times after photoexcitation of the P r state are similar in BV-Agp1 (TABLE ONE), Cph1 (8,15), and phyA (26,27). Adopting the nomenclature established for phyA (25), we therefore assign 2 , 3 , and 4 to the decay times of Lumi-R(Agp1), Meta-R A (Agp1), and Meta-R C (Agp1), respectively. However, the amplitude changes of BV-Agp1 in D 2 O cannot be reconciled with a simple sequential reaction scheme but indicate the involvement of branching and/or back reactions (equilibria).…”

mentioning

confidence: 89%

See 2 more Smart Citations

Light-induced Proton Release of Phytochrome Is Coupled to the Transient Deprotonation of the Tetrapyrrole Chromophore

Borucki

Stetten

Seibeck

et al. 2005

Journal of Biological Chemistry

159

260

View full text Add to dashboard Cite

The P r 3 P fr phototransformation of the bacteriophytochrome Agp1 from Agrobacterium tumefaciens and the structures of the biliverdin chromophore in the parent states and the cryogenically trapped intermediate Meta-R C were investigated with resonance Raman spectroscopy and flash photolysis. Strong similarities with the resonance Raman spectra of plant phytochrome A indicate that in Agp1 the methine bridge isomerization state of the chromophore is ZZZasa in P r and ZZEssa in P fr , with all pyrrole nitrogens being protonated. Photoexcitation of P r is followed by (at least) three thermal relaxation components in the formation of P fr with time constants of 230 s and 3.1 and 260 ms. H 2 O/D 2 O exchange reveals kinetic isotope effects of 1.9, 2.6, and 1.3 for the respective transitions that are accompanied by changes of the amplitudes. The second and the third relaxation correspond to the formation and decay of Meta-R C , respectively. Resonance Raman measurements of Meta-R C indicate that the chromophore adopts a deprotonated ZZE configuration. Measurements with a pH indicator dye show that formation and decay of Meta-R C are associated with proton release and uptake, respectively. The stoichiometry of the proton release corresponds to one proton per photoconverted molecule. The coupling of transient chromophore deprotonation and proton release, which is likely to be an essential element in the P r 3 P fr photoconversion mechanism of phytochromes in general, may play a crucial role for the structural changes in the final step of the P fr formation that switch between the active and the inactive state of the photoreceptor.Phytochromes are photoreceptors that utilize light as a source of information for controlling numerous biological processes (1, 2). The chromophore, a methine-bridged tetrapyrrole ( Fig. 1), acts as a photoswitch between two stable, spectrally distinct forms, denoted as P r and P fr according to the red and far-red absorption maxima, respectively. The P r /P fr interconversion is initiated by the rapid Z/E photoisomerization of the C-D methine bridge (3), followed by chromophore relaxations that are coupled to structural changes of the apoprotein (4). These structural changes are the trigger for signal transduction. Resonance Raman (RR) 2 and IR spectroscopy have provided valuable insight into light-induced chromophore and protein structural changes (e.g. see Refs. 5-10), but molecular and mechanistic details are not yet known and no crystal structure of a phytochrome has been reported so far.While phytochromes were originally thought to be restricted to plants, the discovery of these chromoproteins in cyanobacteria (11) and other bacteria points to the prokaryotic origin of this family of photoreceptors. In contrast to plant phytochromes, typical bacterial phytochromes are light-regulated histidine kinases. Despite the quite different regulatory functions (12, 13), plant and bacterial phytochromes exhibit structural and mechanistic similarities. The phytochromobilin chromophore of plant phytoc...

show abstract

Section: Resultssupporting

confidence: 53%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 89%

See 1 more Smart Citation

Light-induced Proton Release of Phytochrome Is Coupled to the Transient Deprotonation of the Tetrapyrrole Chromophore

Borucki

Stetten

Seibeck

et al. 2005

Journal of Biological Chemistry

159

260

View full text Add to dashboard Cite

show abstract

“…By contrast, photochemistry of phytochrome hardly depends on solvent viscosity (Ruzsicska et al, 1985), but rather appears to depend more on internal modes of the protein. It already shows changes at 205 K (Kendrick and Spruit, 1977), but even below 175 K, phytochrome can be photo-driven effectively (> 50%) to the first intermediate (Eilfeld and Rüdiger, 1985), which has probably already undergone Z/E isomerization (Eilfeld and Eilfeld, 1988). In phytochrome, the phytochromobilin chromophore is probably located in an apoprotein pocket and the reversible photochemistry of the chromophore is mainly assisted by near-by groups of apoprotein (Schaffner et al, 1990).…”

Section: Discussionmentioning

confidence: 99%

Intermediates of reversible photochemistry of phycoerythrocyanin α from Mastigocladuslaminosus probed by low temperature absorptionand circular dichroism spectroscopy

Zhao

Scheer²

1999

International Journal of Photoenergy

View full text Add to dashboard Cite

Abstract. The reversible photochemistry of the α-subunit of phycoerythrocyanin (α-PEC) has been measured by low temperature absorption and circular dichroism in the range of 125 K to 295 K. Below 185 K, the photochemistry is nearly silent; above 205 K, the photochemistry increases gradually without an indication of intermediates, and between 185 to 205 K spectral changes in absorption and circular dichroism indicate an intermediate and/or changes in the interaction(s) between the chromophore and its environment.

show abstract

“…The recombinant proteins were overexpressed in Escherichia coli LMG194 and purified as previously described (15). To test the reduction/oxidation of the BphP3 B BTAi1 protein, reducing conditions were created with 1 mM dithiothreitol (DTT) and oxidizing conditions with 1 mM K 3 Fe(CN) 6 . After addition of the oxidizing or reducing reagent, the protein samples were incubated for at least 30 min on ice and then analyzed by nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).…”

Section: Methodsmentioning

confidence: 99%

Control of Peripheral Light-Harvesting Complex Synthesis by a Bacteriophytochrome in the Aerobic Photosynthetic Bacterium Bradyrhizobium Strain BTAi1

et al. 2008

View full text Add to dashboard Cite

The recent sequence analysis of the photosynthetic and plant-symbiotic Bradyrhizobium sp. strain BTAi1 revealed the unexpected presence of a pucBA operon encoding the apoproteins of peripheral light-harvesting (LH) complexes. This pucBA operon is found close to a bacteriophytochrome gene (BphP3 B BTAi1 ) and a two-component transcriptional regulator gene (TF BTAi1 gene). In this study, we show that BphP3 B BTAi1 acts as a bona fide bacteriophytochrome and controls, according to light conditions, the expression of the pucBA operon found in its vicinity. This light regulatory pathway is very similar to the one previously described for chromo-BphP4 Rp in Rhodopseudomonas palustris and conducts the synthesis of a peripheral LH complex. This LH complex presents a single absorption band at low temperature, centered at 803 nm. Fluorescence emission analysis of intact cells indicates that this peripheral LH complex does not act as an efficient light antenna. One putative function of this LH complex could be to evacuate excess light energy in order to protect Bradyrhizobium strain BTAi1, an aerobic anoxygenic photosynthetic bacterium, against photooxidative damage during photosynthesis.Anoxygenic phototrophic bacteria have the ability to transform light energy into biochemical amenable energy for their growth and motion. The collection of light and its transformation into chemical energy are mediated by the so-called photosynthetic apparatus. This complex system is composed of three multimeric transmembrane protein complexes: the lightharvesting (LH) complexes, the photochemical reaction center (RC), and the cytochrome bc 1 complex located in the intracytoplasmic membrane. Light collected by the peripheral LH complexes is transferred first to the LH1 complex, which absorbs at around 870 nm, and then to the RC, where a charge separation occurs. This initiates a cyclic electron transfer between the RC and cytochrome bc 1 via electron carrier proteins in the periplasmic space and quinone molecules in the membrane. This cyclic electron transfer is coupled to the translocation of protons and to the formation of a proton motive force across the inner membrane, ultimately used for ATP synthesis. To optimize light collection, various peripheral LH complexes, coded by different pucBA genes, are expressed according to environmental conditions. In most cases, peripheral LH complexes absorb at 800 and 850 nm and are designated LH2. However, other peripheral LH complexes, which differ by their absorption properties and carotenoid content, have been described. At low light intensities and/or low temperatures, Rhodopseudomonas acidophila synthesizes an LH complex, designated LH3, which absorbs at 800 and 820 nm (4, 8). An atypical LH complex (LH4), presenting a single band around 805 nm, is synthesized by Rhodopseudomonas palustris cells when grown at a low light intensity (16).In general, the photosynthetic activity of anoxygenic phototrophic bacteria takes place under anaerobic or semiaerobic conditions, since the synthesis of the ph...

show abstract

Absorption Spectra of Phytochrome Intermediates

Cited by 100 publications

References 12 publications

Light-induced Proton Release of Phytochrome Is Coupled to the Transient Deprotonation of the Tetrapyrrole Chromophore

Light-induced Proton Release of Phytochrome Is Coupled to the Transient Deprotonation of the Tetrapyrrole Chromophore

Intermediates of reversible photochemistry of phycoerythrocyanin α from Mastigocladuslaminosus probed by low temperature absorptionand circular dichroism spectroscopy

Control of Peripheral Light-Harvesting Complex Synthesis by a Bacteriophytochrome in the Aerobic Photosynthetic Bacterium Bradyrhizobium Strain BTAi1

Contact Info

Product

Resources

About