Shinji Masuda

The sensor of blue-light using FAD (BLUF) domain is the flavin-binding fold categorized to a new class of blue-light sensing domain found in AppA from Rhodobacter sphaeroides and PAC from Euglena gracilis, but little is known concerning the mechanism of blue-light perception. An open reading frame slr1694 in a cyanobacterium Synechocystis sp. PCC6803 encodes a protein possessing the BLUF domain. Here, a full-length Slr1694 protein retaining FAD was expressed and purified and found to be present

AppA is a new class blue-light receptor controlling photosynthesis gene expression in the purple bacterium Rhodobacter sphaeroides and retains a characteristic flavin adenine dinucleotide (FAD)-binding domain named the "sensor of blue light using FAD" (BLUF). AppA functions as an antirepressor controlling transcription of photosynthesis genes through the direct association with a transcriptional repressor PpsR in a blue-light-dependent manner [Masuda and Bauer (2002) Cell 110, 613-623]. Illumina

BLUF (sensor of blue light using FAD) domain-containing proteins are one of three types of flavin-binding, blue-light-sensing proteins found in many bacteria and some algae. The other types of blue-light-sensing proteins are the cryptochromes and the light, oxygen, voltage (LOV) domain-containing proteins. BLUF proteins control a wide variety of light-dependent physiological activities including photosystem synthesis, biofilm formation and the photoavoidance response. The BLUF domain photochemic

Sulfide was used as an electron donor early in the evolution of photosynthesis, with many extant photosynthetic bacteria still capable of using sulfur compounds such as hydrogen sulfide (H₂S) as a photosynthetic electron donor. Although enzymes involved in H₂S oxidation have been characterized, mechanisms of regulation of sulfide-dependent photosynthesis have not been elucidated. In this study, we have identified a sulfide-responsive transcriptional repressor, SqrR, that fu

Many species of purple photosynthetic bacteria repress synthesis of their photosystem in the presence of molecular oxygen. The bacterium Rhodobacter capsulatus mediates this process by repressing expression of bacteriochlorophyll, carotenoid, and light-harvesting genes via the aerobic repressor, CrtJ. In this study, we demonstrate that CrtJ forms an intramolecular disulfide bond in vitro and in vivo when exposed to oxygen. Mutational and sulfhydryl-specific chemical modification studies indicate

AppA is a member of an FAD-based new class blue-light sensory protein known as sensor of blue light using FAD (BLUF) protein. The spectroscopic properties of an AppA BLUF domain (AppA126), in which the tryptophan residue at position 104 had been replaced with alanine (W104A), were characterized. The W104A mutant AppA126 showed a nearly normal absorption red shift in the FAD UV-visible absorption upon illumination; however, the light state relaxed to the dark state at a rate approximately 150 tim

The chloroplast, an essential organelle for plants, performs a wide variety of metabolic processes for host cells, which include photosynthesis as well as amino acid and fatty acid biosynthesis. The organelle conserves many bacterial systems in its functions, implicating its origin from symbiosis of a photosynthetic bacterium. In bacterial cells, the stringent response acts as a global regulatory system for gene expression mediated by a small nucleotide, guanosine 5'-diphosphate 3'-diphosphate (

Genes coding for putative RegA, RegB, and SenC homologues were identified and characterized in the purple nonsulfur photosynthetic bacteria Rhodovulum sulfidophilum and Roseobacter denitrificans, species that demonstrate weak or no oxygen repression of photosystem synthesis. This additional sequence information was then used to perform a comparative analysis with previously sequenced RegA, RegB, and SenC homologues obtained from Rhodobacter capsulatus and Rhodobacter sphaeroides. These are photo

The pH of various chloroplast compartments, such as the thylakoid lumen and stroma, is light-dependent. Light illumination induces electron transfer in the photosynthetic apparatus, coupled with proton translocation across the thylakoid membranes, resulting in acidification and alkalization of the thylakoid lumen and stroma, respectively. Luminal acidification is crucial for inducing regulatory mechanisms that protect photosystems against photodamage caused by the overproduction of reactive oxyg

PixD/Slr1694 from the cyanobacterium Synechocystis sp. PCC6803 is a member of a new class of flavin-containing blue-light sensory proteins containing a BLUF (blue light using flavin) domain. The photocycle reaction mechanism of BLUF is unique because only small structural changes of a bound chromophore are accompanied by a few hydrogen bond rearrangements in the chromophore-binding site. Here, we show that in PixD, Met93, the residue conserved in all BLUF domains, is crucial for light-dependent