Disease relevance of phy

• Biochemical analyses demonstrate that phytochrome is an ancient molecule that evolved from a more compact light sensor in cyanobacteria [1].
• Chromophore-apoprotein interactions in Synechocystis sp. PCC6803 phytochrome Cph1 [2].
• The 85-kDa phytochrome Cph1 from the cyanobacterium Synechocystis PCC 6803 expressed in Escherichia coli was reconstituted with phycocyanobilin (Cph1-PCB) and phycoerythrobilin (Cph1-PEB) [3].
• The Ppr protein of the anoxygenic photosynthetic bacterium Rhodospirillum centenum and the bacterial phytochrome-like proteins (BphP) of Deinococcus radiodurans and Pseudomonas aeruginosa fall within the cluster of cyanobacterial phytochromes [4].
• The Raman spectra suggest far-reaching similarities in chromophore configuration and conformation between the Pfr forms of Synechocystis phytochrome and the plant phytochromes (e.g. phyA from oat), but some differences, such as torsions around methine bridges and in hydrogen bonding interactions, in the Pr state [5].

High impact information on phy

• In addition to identifying a small region of the apoprotein critical for maintaining phytochrome's native spectroscopic properties, our studies revealed a tyrosine-to-histidine mutation that transformed phytochrome into an intensely red fluorescent biliprotein [6].
• Interestingly, whereas the C-terminal region of the TaxD1 polypeptide is similar to the signaling domain of enteric methyl-accepting chemoreceptor proteins, the N terminus has two domains resembling chromophore-binding domains of phytochrome, a photoreceptor in plants [7].
• Phycocyanobilin and similar tetrapyrroles are covalently attached within seconds, an autocatalytic process followed by slow conformational changes culminating in red-absorbing phytochrome formation [8].
• The complete sequence of the Synechocystis chromosome has revealed a phytochrome-like sequence that yielded an authentic phytochrome when overexpressed in Escherichia coli [8].
• Precise structural information regarding the chromophore binding pocket is essential for an understanding of photochromicity and photoconversion in phytochrome photoreceptors [9].

Chemical compound and disease context of phy

• The formation of the Pfr state of the PCB adduct of Synechocystis phytochrome shows a deuterium effect similar as phyA (ca. 1.2) [5].
• Ultrafast dynamics of phytochrome from the cyanobacterium synechocystis, reconstituted with phycocyanobilin and phycoerythrobilin [3].
• The kinetics and mechanism of the autocatalytic assembly of holo-Cph1 phytochrome (from Synechocystis) from the apoprotein and the bilin chromophores phycocyanobilin (PCB) and phycoerythrobilin (PEB) were investigated by stopped flow and circular dichroism [10].
• A gene that may encode a novel light sensing histidine protein kinase, designated plpA (phytochrome-like protein), was isolated from the cyanobacterium Synechocystis sp. PCC 6803 [11].

Biological context of phy

• Crystal structures of two cyanobacterial response regulators in apo- and phosphorylated form reveal a novel dimerization motif of phytochrome-associated response regulators [12].
• These transient structural changes may be relevant for signal transduction by this cyanobacterial phytochrome [13].
• Mechanism of Cph1 phytochrome assembly from stopped-flow kinetics and circular dichroism [10].
• We investigated the dimerization of phytochrome Cph1 from the cyanobacterium Synechocystis by fluorescence resonance energy transfer (FRET) [14].
• Through pattern searches of genomic databases, new members of the growing family of phytochrome-related genes were identified and used to construct a 130-180 amino acid motif that delimits the bilin lyase domain, a subdomain of the extended phytochrome family that is sufficient for covalent attachment of linear tetrapyrroles (bilins) [15].

Associations of phy with chemical compounds

• The CD spectra of the PCB adduct in the 250-800 nm range show that the chromophore geometries in P(r) and P(fr) are similar to those in plant phytochrome [10].
• Both RRs are members of phytochrome-associated, light-sensing two-component signal transduction pathways, based on histidine kinase-mediated receptor autophosphorylation and phosphorelay to a RR [12].
• Site-directed mutagenesis of highly conserved charged residues within bilin lyase domains of nearly all members of the extended phytochrome superfamily has identified a glutamate residue critical for bilin binding [15].
• An Arabidopsis thaliana hy1 mutant was previously shown to be deficient in phytochrome responses, and these responses were regained when the plants were administered biliverdin IXalpha [16].

Physical interactions of phy

• Interestingly, sll0041 (designated pisJ1) is predicted to have a chromophore-binding motif of phytochrome-like proteins and a signaling motif of chemoreceptors for bacterial chemotaxis [17].

Other interactions of phy

• To test this hypothesis, portions of locus sll0821, a novel phytochrome-related gene from Synechocystis sp. PCC6803 that encodes a large protein with two potential bilin binding sites, were amplified, and the recombinant apoproteins were tested for bilin binding and phytochrome photoactivity [15].

Analytical, diagnostic and therapeutic context of phy

• The secondary, tertiary, and quaternary structures of the Synechocystis Cph1 phytochrome were investigated by absorption and circular dichroism spectroscopy, size exclusion chromatography, and limited proteolysis [2].
• Nevertheless, the purity and solubility of the recombinant gene product make it a most attractive model for molecular studies of phytochrome, including x-ray crystallography [8].
• Sequence alignments reveal that the identified dimerization motif is archetypal for phytochrome-associated RRs, making them a novel subgroup of CheY-type RRs [12].
• Crystallization and preliminary X-ray crystallographic studies of response regulator for cyanobacterial phytochrome, Rcp1 [18].
• The reversible red and far-red light-induced transitions of cyanobacterial phytochrome Cph1 from Synechocystis PCC 6803 were investigated by Fourier transform infrared (FTIR) difference spectroscopy [19].

References