Showing papers on "Phycoerythrobilin published in 2003"
TL;DR: The kinetics and mechanism of the autocatalytic assembly of holo-Cph1 phytochrome from the apoprotein and the bilin chromophores phycocyanobilin (PCB) and phycoerythrobilin (PEB) were investigated by stopped flow and circular dichroism.
Abstract: 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. At 1:1 stoichiometry, pH 7.9, and 10 °C, SVD analysis of the kinetic data for PCB revealed three spectral components involving three transitions with time constants τ1 ∼ 150 ms, τ2 ∼ 2.5 s, and τ3 ∼ 50 s. τ1 was associated with a major red shift and transfer of oscillator strength from the Soret region to the 680 nm region. When the sulfhydryl group of cysteine 259 was blocked with iodoacetamide, preventing the formation of a covalent adduct, a noncovalent red-shifted complex (680 nm) was formed with a time constant of 200 ms. τ1 could thus be assigned to the formation of a noncovalent complex. The absorption changes during τ1 are due to the formation of the extended conformation of the linear tetrapyrrole and to its protonation in the binding pocket. ...
59 citations
TL;DR: The capacity of PE to function primarily as a photosynthetic light‐harvesting pigment in P. marinus SS120 is low, according to spectroscopic characterisation of these DV‐Chls and PE.
47 citations
TL;DR: Regulation of the expression of the pebAB operon is coordinated at the level of RNA accumulation by the recently discovered activator CpeR, which encodes the enzymes required for phycoerythrobilin synthesis in the filamentous cyanobacterium Fremyella diplosiphon.
Abstract: We have characterized the regulation of the expression of the pebAB operon, which encodes the enzymes required for phycoerythrobilin synthesis in the filamentous cyanobacterium Fremyella diplosiphon. The expression of the pebAB operon was found to be regulated during complementary chromatic adaptation, the system that controls the light responsiveness of genes that encode several light-harvesting proteins in F. diplosiphon. Our analyses of pebA mutants demonstrated that although the levels of phycoerythrin and its associated linker proteins decreased in the absence of phycoerythrobilin, there was no significant modulation of the expression of pebAB and the genes that encode phycoerythrin. Instead, regulation of the expression of these genes is coordinated at the level of RNA accumulation by the recently discovered activator CpeR.
41 citations
TL;DR: Evidence for energy transfer in Cph1 dimers was obtained from dilution experiments with PEB/PEB dimers: the lifetime was unchanged, but the anisotropy increased as the dimers dissociated with increasing dilution, providing strong support for inter-chromophore hetero energyTransfer in mixedPEB/PCB dimer
Abstract: We investigated the dimerization of phytochrome Cph1 from the cyanobacterium Synechocystis by fluorescence resonance energy transfer (FRET). As donor we used the chromophore analogue phycoerythrobilin (PEB) and as acceptor either the natural chromophore phycocyanobilin (PCB; hetero transfer) or PEB (homo transfer). Both chromophores bind in a 1:1 stoichiometry to apo-monomers expressed in Escherichia coli. Energy transfer was characterized by time-resolved fluorescence intensity and anisotropy decay after excitation of PEB by picosecond pulses from a tunable Ti-sapphire laser system. ApoCph1 was first assembled with PEB at a low stoichiometry of 0.1. The remaining sites were then sequentially titrated with PCB. In the course of this titration, the mean lifetime of PEB decreased from 3.33 to 1.25 ns in the Pr form of Cph1, whereas the anisotropy decay was unaffected. In the Pfr/Pr photoequilibrium (about 65% Pfr), the mean lifetime decreased significantly less, to 1.67 ns. These observations provide strong...
39 citations