Understanding Two Different Structures in the Dark Stable State of the Oxygen-Evolving Complex of Photosystem II: Applicability of the Jahn-Teller Deformation Formula.

Tanaka et al. (., , , 1718) recently reported the three-dimensional (3D) structure of the oxygen evolving complex (OEC) of photosystem II (PSII) by X-ray diffraction (XRD) using extremely low X-ray doses of 0.

Two Different Structures of the Oxygen-Evolving Complex in the Same Polypeptide Frameworks of Photosystem II.

The oxygen-evolving complex (OEC) forms the heart of photosystem II (PSII) in photosynthesis. The crystal structure of PSII from Thermosynechococcus vulcanus has been reported at a resolution of 1.9 Å and at an averaged X-ray dose of 0.

Three different mechanisms of energy dissipation of a desiccation-tolerant moss serve one common purpose: to protect reaction centres against photo-oxidation.

Three different types of non-photochemical de-excitation of absorbed light energy protect photosystem II of the sun- and desiccation-tolerant moss Rhytidium rugosum against photo-oxidation. The first mechanism, which is light-induced in hydrated thalli, is sensitive to inhibition by dithiothreitol. It is controlled by the protonation of a thylakoid protein.

Two functional sites of phosphatidylglycerol for regulation of reaction of plastoquinone Q(B) in photosystem II.

Functional roles of an anionic lipid phosphatidylglycerol (PG) were studied in pgsA-gene-inactivated and cdsA-gene-inactivated/phycobilisome-less mutant cells of a cyanobacterium Synechocystis sp. PCC 6803, which can grow only in PG-supplemented media. 1) A few days of PG depletion suppressed oxygen evolution of mutant cells supported by p-benzoquinone (BQ).

Photoconversion mechanism of a green/red photosensory cyanobacteriochrome AnPixJ: time-resolved optical spectroscopy and FTIR analysis of the AnPixJ-GAF2 domain.

The photoconversion mechanism of a green/red sensory cyanobacteriochrome AnPixJ was studied. The phycocyanobilin-binding second GAF domain of AnPixJ of Anabaena sp. PCC 7120 was expressed in Escherichia coli cells.

Acceleration of electron-transfer-induced fluorescence quenching upon conversion to the signaling state in the blue-light receptor, TePixD, from Thermosynechococcus elongatus.

TePixD is a blue light using flavin (BLUF) protein of a thermophilic cyanobacterium, Thermosynechococcus elongatus. The fluorescence dynamics of TePixD was observed for the first time in both its dark-adapted and signaling (red-shifted) forms with a 200-fs time resolution. The fluorescence up-conversion setup was used in the time region up to 60 ps, and the streak-camera setup was used in the time region up to 1 ns.

Formation of interacting spins on flavosemiquinone and tyrosine radical in photoreaction of a blue light sensor BLUF protein TePixD.

Light-induced radicals were detected by electron paramagnetic resonance (EPR) and pulsed electron-nuclear double resonance (ENDOR) in the BLUF-domain protein TePixD of the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1. The illumination of TePixD at 5-200 K derived an EPR signal with a separation of 85 G between the main peaks around g = 2, showing a typical Pake's pattern of magnetic dipole-dipole interaction between two nearby radicals. Longer illumination induced an EPR signal at g = 2.

A novel photoactive GAF domain of cyanobacteriochrome AnPixJ that shows reversible green/red photoconversion.

We report the discovery of a novel cyanobacteriochrome, the green/red photoreceptor AnPixJ (All1069), isolated from the heterocyst-forming cyanobacterium Anabaena (Nostoc) sp. PCC 7120. Cyanobacteriochromes are a recently emerging tetrapyrrole-based photoreceptor superfamily that are distantly related to the conventional red/far-red photoreceptor phytochromes (Phys).

Photoreactions of Tyr8- and Gln50-mutated BLUF domains of the PixD protein of Thermosynechococcus elongatus BP-1: photoconversion at low temperature without Tyr8.

We studied the photoreaction of a blue-light sensor PixD protein of Thermosynechococcus elongatus that has the blue-light-using flavin (BLUF) domain. The Tyr8 and Gln50 residues of the protein were modified to phenylalanine, alanine, or asparagine (Y8F, Y8A, Q50N, and Q50A) by site-directed mutagenesis. The following results were obtained.

Fate determination of the flavin photoreceptions in the cyanobacterial blue light receptor TePixD (Tll0078).

PixD (Tll0078, Slr1694) is a BLUF (sensor of blue light using FAD)-type blue light receptor protein of the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1 and the mesophilic cyanobacterium Synechocystis sp. PCC 6803. BLUF protein is known to show light-induced approximately 10 nm red shift of flavin absorption that is coupled with strengthening of the hydrogen bond between the O(4) of the isoalloxazine ring and a certain amino acid residue.

Two intermediate states I and J trapped at low temperature in the photocycles of two BLUF domain proteins of cyanobacteria Synechocystis sp. PCC6803 and Thermosynechococcus elongatus BP-1.

We identified the two intermediate states, I and J, that are common in the photocycles of the cyanobacterial BLUF (sensor of Blue Light Using Flavin) domain proteins of Slr1694 of Synechocystis sp. PCC6803 and Tll0078 of Thermosynechococcus elongatus BP-1 by analyzing the absorption spectra at 5 K. Illumination at 5 K accumulated intermediate forms (designated as I5 and I9), which showed 5 and 9 nm redshifts of the absorption bands of flavin in the Tll0078 and Slr1694 proteins, respectively.

Biochemical and functional characterization of BLUF-type flavin-binding proteins of two species of cyanobacteria.

BLUF (a sensor of Blue-Light Using FAD) is a novel putative photoreceptor domain that is found in many bacteria and some eukaryotic algae. As found on genome analysis, certain cyanobacteria have BLUF proteins with a short C-terminal extension. As typical examples, Tll0078 from thermophilic Thermosynechococcus elongatus BP-1 and Slr1694 from mesophilic Synechocystis sp.

Primary intermediate in the photocycle of a blue-light sensory BLUF FAD-protein, Tll0078, of Thermosynechococcus elongatus BP-1.

Proteins with a BLUF (sensor of blue light using flavin adenine dinucleotide) domain represent a newly recognized class of photoreceptors that is widely distributed in the genomes of photosynthetic bacteria, cyanobacteria, and Euglena. Recently, Okajima et al. [Okajima, K.