A Native LH1-RC-HiPIP Supercomplex from an Extremophilic Phototroph.

Halorhodospira (Hlr.) halophila strain BN9622 is an extremely halophilic and alkaliphilic purple phototrophic bacterium and has been widely used as a model for exploring the osmoadaptive and photosynthetic strategies employed by phototrophic extreme halophiles that enable them to thrive in hypersaline environments. Here we present the cryo-EM structures of (1) a unique native Hlr.

An LH1-RC photocomplex from an extremophilic phototroph provides insight into origins of two photosynthesis proteins.

Rhodopila globiformis is the most acidophilic of anaerobic purple phototrophs, growing optimally in culture at pH 5. Here we present a cryo-EM structure of the light-harvesting 1-reaction center (LH1-RC) complex from Rhodopila globiformis at 2.24 Å resolution.

A Ca-binding motif underlies the unusual properties of certain photosynthetic bacterial core light-harvesting complexes.

The mildly thermophilic purple phototrophic bacterium Allochromatium tepidum provides a unique model for investigating various intermediate phenotypes observed between those of thermophilic and mesophilic counterparts. The core light-harvesting (LH1) complex from A. tepidum exhibits an absorption maximum at 890 nm and mildly enhanced thermostability, both of which are Ca-dependent.

Asymmetric structure of the native Rhodobacter sphaeroides dimeric LH1-RC complex.

Rhodobacter sphaeroides is a model organism in bacterial photosynthesis, and its light-harvesting-reaction center (LH1-RC) complex contains both dimeric and monomeric forms. Here we present cryo-EM structures of the native LH1-RC dimer and an LH1-RC monomer lacking protein-U (ΔU). The native dimer reveals several asymmetric features including the arrangement of its two monomeric components, the structural integrity of protein-U, the overall organization of LH1, and rigidities of the proteins and pigments.

A previously unrecognized membrane protein in the Rhodobacter sphaeroides LH1-RC photocomplex.

Rhodobacter (Rba.) sphaeroides is the most widely used model organism in bacterial photosynthesis. The light-harvesting-reaction center (LH1-RC) core complex of this purple phototroph is characterized by the co-existence of monomeric and dimeric forms, the presence of the protein PufX, and approximately two carotenoids per LH1 αβ-polypeptides.

Photosynthetic Growth and Energy Conversion in an Engineered Phototroph Containing Light-Harvesting Complex 1 and the Reaction Center Complex.

Light-harvesting complex 1 (LH1) of the thermophilic purple sulfur bacterium can be expressed in the purple non-sulfur bacterium and forms a functional RC-LH1 complex with the native reaction center (Nagashima, K. V. P.

Diagnostic significance of apical membranous and cytoplasmic dot-like CD26 expression in encapsulated follicular variant of papillary thyroid carcinoma: a useful marker for capsular invasion.

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and invasive encapsulated follicular variant of papillary thyroid carcinoma (EFV-PTC) are indistinguishable preoperatively. CD26 expression in follicular tumor-uncertain malignant potential (FT-UMP) is reported to be clearly higher than in that without capsular invasion. To verify the diagnostic significance of CD26 immunostaining in EFV-PTC, we examined the expression pattern of CD26 in non-invasive EFV-PTC (NIFTP) and invasive EFV-PTC.

Sequential energy transfer driven by monoexponential dynamics in a biohybrid light-harvesting complex 2 (LH2).

Enhancing the light-harvesting potential of antenna components in a system of solar energy conversion is an important topic in the field of artificial photosynthesis. We constructed a biohybrid light-harvesting complex 2 (LH2) engineered from Rhodobacter sphaeroides IL106 strain. An artificial fluorophore Alexa Fluor 647 maleimide (A647) was attached to the LH2 bearing cysteine residue at the N-terminal region (LH2-NC) near B800 bacteriochlorophyll a (BChl) assembly.

Biochemical and Spectroscopic Characterizations of a Hybrid Light-Harvesting Reaction Center Core Complex.

The light-harvesting 1 reaction center (LH1-RC) complex from Thermochromatium tepidum exhibits a largely red-shifted LH1 Q absorption at 915 nm due to binding of Ca, resulting in an "uphill" energy transfer from LH1 to the reaction center (RC). In a recent study, we developed a heterologous expression system (strain TS2) to construct a functional hybrid LH1-RC with LH1 from Tch. tepidum and the RC from Rhodobacter sphaeroides [Nagashima, K.

Probing structure-function relationships in early events in photosynthesis using a chimeric photocomplex.

The native core light-harvesting complex (LH1) from the thermophilic purple phototrophic bacterium requires Ca for its thermal stability and characteristic absorption maximum at 915 nm. To explore the role of specific amino acid residues of the LH1 polypeptides in Ca-binding behavior, we constructed a genetic system for heterologously expressing the LH1 complex in an engineered mutant strain. This system contained a chimeric gene cluster ( from and from ) and was subsequently deployed for introducing site-directed mutations on the LH1 polypeptides.

Effects of the deletion of hup genes encoding the uptake hydrogenase on the activity of hydrogen production in the purple photosynthetic bacterium Rubrivivax gelatinosus IL144.

The efficiency of hydrogen gas production by nitrogenase in bacteria has been improved by the inhibition of antagonistic activity by the uptake hydrogenase. In this study, a mutant lacking the gene coding for the uptake hydrogenase was generated from the photosynthetic beta-proteobacterium Rubrivivax gelatinosus IL144 to explore new ways of hydrogen gas production driven by light energy. The mutant cells produced 25-30% higher amounts of molecular hydrogen than the wild-type cells under nitrogen-deficient conditions under light.

Exchange and complementation of genes coding for photosynthetic reaction center core subunits among purple bacteria.

A mutant of the phototrophic species belonging to the β-proteobacteria, Rubrivivax gelatinosus, lacking the photosynthetic growth ability was constructed by the removal of genes coding for the L, M, and cytochrome subunits of the photosynthetic reaction center complex. The L, M, and cytochrome genes derived from five other species of proteobacteria, Acidiphilium rubrum, Allochromatium vinosum, Blastochloris viridis, Pheospirillum molischianum, and Roseateles depolymerans, and the L and M subunits from two other species, Rhodobacter sphaeroides and Rhodopseudomonas palustris, respectively, have been introduced into this mutant. Introduction of the genes from three of these seven species, Rte.

Complete genome sequence of phototrophic betaproteobacterium Rubrivivax gelatinosus IL144.

Rubrivivax gelatinosus is a facultative photoheterotrophic betaproteobacterium living in freshwater ponds, sewage ditches, activated sludge, and food processing wastewater. There have not been many studies on photosynthetic betaproteobacteria. Here we announce the complete genome sequence of the best-studied phototrophic betaproteobacterium, R.

Diversity of purple phototrophic bacteria, inferred from pufM gene, within epilithic biofilm in Tama River, Japan.

The diversity of purple phototrophic bacteria in algae-dominated biofilm of a streambed in Tama River, Japan was investigated. Clone library analysis of the pufM gene encoding a subunit of the photochemical reaction center of purple bacteria detected 18 operational taxonomic units (OTUs) in several classes of Proteobacteria. Most of the OTUs showed less than 85% identity to the PufM amino acid sequences of known phototrophic bacteria.

Photo-induced electron transfer in intact cells of Rubrivivax gelatinosus mutants deleted in the RC-bound tetraheme cytochrome: insight into evolution of photosynthetic electron transport.

Deletion of two of the major electron carriers, the reaction center-bound tetrahemic cytochrome and the HiPIP, involved in the light-induced cyclic electron transfer pathway of the purple photosynthetic bacterium, Rubrivivax gelatinosus, significantly impairs its anaerobic photosynthetic growth. Analysis on the light-induced absorption changes of the intact cells of the mutants shows, however, a relatively efficient photo-induced cyclic electron transfer. For the single mutant lacking the reaction center-bound cytochrome, we present evidence that the electron carrier connecting the reaction center and the cytochrome bc(1) complex is the High Potential Iron-sulfur Protein.

Photocurrent and electronic activities of oriented-His-tagged photosynthetic light-harvesting/reaction center core complexes assembled onto a gold electrode.

A polyhistidine (His) tag was fused to the C- or N-terminus of the light-harvesting (LH1)-α chain of the photosynthetic antenna core complex (LH1-RC) from Rhodobacter sphaeroides to allow immobilization of the complex on a solid substrate with defined orientation. His-tagged LH1-RCs were adsorbed onto a gold electrode modified with Ni-NTA. The LH1-RC with the C-terminal His-tag (C-His LH1-RC) on the modified electrode produced a photovoltaic response upon illumination.

The cytochrome c₈ involved in the nitrite reduction pathway acts also as electron donor to the photosynthetic reaction center in Rubrivivax gelatinosus.

The purple photosynthetic bacterium Rubrivivax gelatinosus has, at least, four periplasmic electron carriers, i.e., HiPIP, two cytochromes c₈with low- and high-midpoint potentials, and cytochrome c₄ as electron donors to the photochemical reaction center.

Cytochrome c4 can be involved in the photosynthetic electron transfer system in the purple bacterium Rubrivivax gelatinosus.

Three periplasmic electron carriers, HiPIP and two cytochromes c8 with low- and high-midpoint potentials, are present in the purple photosynthetic bacterium Rubrivivax gelatinosus. Comparison of the growth rates of mutants lacking one, two, or all three electron carrier proteins showed that HiPIP is the main electron donor to the photochemical reaction center and that high-potential cytochrome c8 plays a subsidiary role in the electron donation in photosynthetically growing cells. However, the triple deletion mutant was still capable of photosynthetic growth, indicating that another electron donor could be present.

Characterization of a blue-copper protein, auracyanin, of the filamentous anoxygenic phototrophic bacterium Roseiflexus castenholzii.

A blue-copper protein auracyanin of the filamentous anoxygenic phototroph Roseiflexus castenholzii was purified and characterized. Genomic sequence analysis showed that R. castenholzii has only one auracyanin, whereas Chloroflexus aurantiacus is known to have two auracyanins, A and B.

Cerebroside elicitor confers resistance to fusarium disease in various plant species.

ABSTRACT In the rice blast fungus pathosystem, cerebroside, a compound categorized as a sphingolipid, was found in our previous study to be a non-racespecific elicitor, which elicits defense responses in rice. Here we describe that cerebroside C is produced in diverse strains of Fusarium oxysporum, a common soilborne agent of wilt disease affecting a wide range of plant species. In addition, some type of cerebroside elicitor involving cerebroside A, B, or C was detected in other soilborne phytopathogens, such as Pythium and Botrytis.

A new membrane-bound cytochrome c works as an electron donor to the photosynthetic reaction center complex in the purple bacterium, Rhodovulum sulfidophilum.

A new type of membrane-bound cytochrome c was found in a marine purple photosynthetic bacterium, Rhodovulum sulfidophilum. This cytochrome c was significantly accumulated in cells growing under anaerobic photosynthetic conditions and showed an apparent molecular mass of approximately 100 kDa when purified and analyzed by SDS-PAGE. The midpoint potential of this cytochrome c was 369 mV.

Kinetic performance and energy profile in a roller coaster electron transfer chain: a study of modified tetraheme-reaction center constructs.

In many electron-transfer proteins, the arrangement of cofactors implies a succession of uphill and downhill steps. The kinetic implications of such arrangements are examined in the present work, based on a study of chimeric photosynthetic reaction centers obtained by expressing the tetraheme subunit from Blastochloris viridis in another purple bacterium, Rubrivivax gelatinosus. Site-directed mutations of the environment of heme c559, which is the immediate electron donor to the primary donor P, induced modifications of this heme's midpoint potential over a range of 400 mV.

Transcription of three sets of genes coding for the core light-harvesting proteins in the purple sulfur bacterium, Allochromatium vinosum.

The nucleotide sequence of the puf operon coding for the subunits of the photosynthetic reaction center and the core light-harvesting complex (LH1) of the purple sulfur bacterium, Allochromatium (A.) vinosum (formally Chromatium vinosum), was completely determined. Unlike other known puf operons, which contain only one set of genes coding for the LH1 apoproteins, pufB and pufA, the A.

Phylogenetic distribution of unusual triheme to tetraheme cytochrome subunit in the reaction center complex of purple photosynthetic bacteria.

To understand the evolutionary relationship between triheme and tetraheme cytochrome subunits in the reaction center complex, genes located downstream of that coding for the M subunit of the reaction center complex (pufM) were amplified by PCR and analyzed in six established and two unidentified species of the genus Rhodovulum and five species of the genus Rhodobacter. All the Rhodovulum species tested had the pufC gene coding for the reaction-center-bound cytochrome subunit, while all the Rhodobacter species were found to have the pufX gene at the corresponding position. Analyses of the amino acid sequences of the pufC gene products showed that the cytochrome subunits of all the Rhodovulum species have three heme-binding-motifs and lack a methionine residue probably working as the sixth axial-ligand to one of the three hemes.