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A G Yakovlev, V A Shuvalov
Energy relaxation was studied with difference femtosecond spectroscopy in reaction centers of the YM210L mutant of the purple photosynthetic bacterium Rhodobacter sphaeroides at low temperature (90 K). A dynamical long-wavelength shift of stimulated emission of the excited state of the bacteriochlorophyll dimer P was found, which starts simultaneously with P* formation and is accompanied by a change in the spectral shape of this emission. The characteristic value of this shift was about 30 nm, and the characteristic time about 200 fs...
August 2017: Biochemistry. Biokhimii︠a︡
Daniel Gräsing, Pavlo Bielytskyi, Isaac F Céspedes-Camacho, A Alia, Thorsten Marquardsen, Frank Engelke, Jörg Matysik
Several parameters in NMR depend on the magnetic field strength. Field-cycling NMR is an elegant way to explore the field dependence of these properties. The technique is well developed for solution state and in relaxometry. Here, a shuttle system with magic-angle spinning (MAS) detection is presented to allow for field-dependent studies on solids. The function of this system is demonstrated by exploring the magnetic field dependence of the solid-state photochemically induced nuclear polarization (photo-CIDNP) effect...
September 21, 2017: Scientific Reports
Kenji V P Nagashima, Mai Sasaki, Kanako Hashimoto, Shinichi Takaichi, Sakiko Nagashima, Long-Jiang Yu, Yuto Abe, Kenta Gotou, Tomoaki Kawakami, Mizuki Takenouchi, Yuuta Shibuya, Akira Yamaguchi, Takashi Ohno, Jian-Ren Shen, Kazuhito Inoue, Michael T Madigan, Yukihiro Kimura, Zheng-Yu Wang-Otomo
The native core light-harvesting complex (LH1) from the thermophilic purple phototrophic bacterium Thermochromatium tepidum requires Ca(2+) 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 Tch. tepidum LH1 complex in an engineered Rhodobacter sphaeroides mutant strain. This system contained a chimeric pufBALM gene cluster (pufBA from Tch...
September 21, 2017: Proceedings of the National Academy of Sciences of the United States of America
Anne-Marie Carey, Haojie Zhang, Minghui Liu, Daiana Sharaf, Natalie Akram, Hao Yan, Su Lin, Neal Woodbury, Dong-Kyun Seo
3 to 4 times higher performance of biohybrid photoelectrochemical cells with photosynthetic reaction centers (RC) has been achieved by using a DNA-based biomimetic antenna. Synthetic dyes Cy3 and Cy5 were chosen and strategically placed in the anntena in such a way that they can collect additional light energy in the visible region of the solar spectrum and transfer it to RC through Förster resonance energy transfer (FRET). The antenna, a DNA templated multiple dye system, is attached to each Rhodobacter sphaeroides RC near the primary donor, P, to facilitate the energy transfer process...
September 19, 2017: ChemSusChem
Linna Danne, Meriyem Aktas, Nadine Grund, Tim Bentler, Ralf Erdmann, Franz Narberhaus
Bacterial phospholipid N-methyltransferases (Pmts) catalyze the formation of phosphatidylcholine (PC) via successive N-methylation of phosphatidylethanolamine (PE). They are classified into Sinorhizobium-type and Rhodobacter-type enzymes. The Sinorhizobium-type PmtA protein from the plant pathogen Agrobacterium tumefaciens is recruited to anionic lipids in the cytoplasmic membrane via two amphipathic helices called αA and αF. Besides its enzymatic activity, PmtA is able to remodel membranes mediated by the αA domain...
September 11, 2017: Biochimica et Biophysica Acta
Ziliang Mao, Elizabeth C Carroll, Peter W Kim, Stephen P Cramer, Delmar S Larsen
Iron-sulfur proteins play essential roles in various biological processes. Their electronic structure and vibrational dynamics are key to their rich chemistry but nontrivial to unravel. Here, the first ultrafast transient absorption and impulsive coherent vibrational spectroscopic (ICVS) studies on 2Fe-2S clusters in Rhodobacter capsulatus ferreodoxin VI are characterized. Photoexcitation initiated populations on multiple excited electronic states that evolve into each other in a long-lived charge-transfer state...
September 7, 2017: Journal of Physical Chemistry Letters
Alexander B Westbye, Zoe O'Neill, Tegan Schellenberg-Beaver, J Thomas Beatty
Small bacteriophage-like particles called gene transfer agents (GTAs) that mediate DNA transfer between cells are produced by a variety of prokaryotes. The model GTA, produced by the alphaproteobacterium Rhodobacter capsulatus (RcGTA), is controlled by several cellular regulators, and production is induced upon entry into the stationary phase. We report that RcGTA production and gene transfer are stimulated by nutrient depletion. Cells depleted of organic carbon or blocked for amino acid biosynthesis increased RcGTA production and release from cells...
September 4, 2017: Microbiology
Xiaohui Wang, Quan Zheng, Yuan Yuan, Reti Hai, Dexun Zou
The potential environmental risks of chromium oxide nanoparticles (Cr2O3 NPs) have caused great concerns. However, their possible impacts on activated sludge process are very limited. In this study, we carried out long-term exposure experiments to evaluate the influence of Cr2O3 NPs on wastewater nutrient removal, bacterial community and molecular ecological network (MEN) in the sequencing batch reactor (SBR). It was found that 1 mg/L Cr2O3 NPs increased the effluent concentrations of NO3(-)-N and TP from 6...
August 16, 2017: Chemosphere
G Suresh, B Sailaja, A Ashif, Bharti P Dave, Ch Sasikala, Ch V Ramana
Three strains (JA826T, JA912T and JA913), which were yellowish brown colour, rod to oval shaped, Gram-stain-negative, motile, phototrophic bacteria with a vesicular architecture of intracytoplasmic membranes, were isolated from different pond samples. The DNA G+C content of the three strains was between 64.6 and 65.5 mol%. The highest 16S rRNA gene sequence similarity of all three strains was with the type strains of the genus Rhodobacter sensu stricto in the family Rhodobacteraceae. Strain JA826T had highest sequence similarity with Rhodobacter maris JA276T (98...
September 2017: International Journal of Systematic and Evolutionary Microbiology
David J K Swainsbury, Elizabeth C Martin, Cvetelin Vasilev, Pamela S Parkes-Loach, Paul A Loach, C Neil Hunter
The reaction centre-light harvesting 1 (RC-LH1) complex of Thermochromatium (Tch.) tepidum has a unique calcium-ion binding site that enhances thermal stability and red-shifts the absorption of LH1 from 880nm to 915nm in the presence of calcium-ions. The LH1 antenna of mesophilic species of phototrophic bacteria such as Rhodobacter (Rba.) sphaeroides does not possess such properties. We have engineered calcium-ion binding into the LH1 antenna of Rba. sphaeroides by progressively modifying the native LH1 polypeptides with sequences from Tch...
August 18, 2017: Biochimica et Biophysica Acta
D Jun, V Huang, J T Beatty
The photosynthetic complexes of the thermophile Thermochromatium tepidum are of considerable interest in biohybrid solar cell applications because of the capability of thermophilic proteins to tolerate elevated temperatures. Synthetic operons encoding reaction centre (RC) and light harvesting 1 (LH1) pigment-protein complexes of T. tepidum were expressed in the mesophile Rhodobacter sphaeroides The T. tepidum RC (TRC) was assembled, and functional with the addition of menadione to populate the QA pocket. The production of the T...
August 18, 2017: Applied and Environmental Microbiology
Kyle T Brown, Sophia C Levis, Casey E O'Neill, Alexis L Northcutt, Timothy J Fabisiak, Linda R Watkins, Ryan K Bachtell
Cocaine addiction is a chronic relapsing disorder characterized by persistent perturbations to an organism's homeostatic processes that result in maladaptive drug seeking. Although considerable attention has been directed at the consequences of neuronal changes following chronic cocaine taking, few studies have examined the role of microglia, the brain's resident immune cells, following chronic cocaine administration. Toll-Like Receptor 4 (TLR4) is a molecular pattern receptor that recognizes pathogens, danger signals, and xenobiotics and induces proinflammatory signaling in the central nervous system...
August 13, 2017: Brain, Behavior, and Immunity
Karel Kopejtka, Jürgen Tomasch, Yonghui Zeng, Martin Tichý, Dimitry Y Sorokin, Michal Koblížek
A characteristic feature of the order Rhodobacterales is the presence of a large number of photoautotrophic and photoheterotrophic species containing bacteriochlorophyll. Interestingly, these phototrophic species are phylogenetically mixed with chemotrophs. To better understand the origin of such variability, we sequenced the genomes of three closely related haloalkaliphilic species, differing in their phototrophic capacity and oxygen preference: the photoheterotrophic and facultatively anaerobic bacterium Rhodobaca barguzinensis, aerobic photoheterotroph Roseinatronobacter thiooxidans, and aerobic heterotrophic bacterium Natronohydrobacter thiooxidans...
July 1, 2017: Genome Biology and Evolution
Fei Ma, David J K Swainsbury, Michael R Jones, Rienk van Grondelle
Engineering natural photosynthesis to address predicted shortfalls in food and energy supply requires a detailed understanding of its molecular basis and the intrinsic photoprotective mechanisms that operate under fluctuating environmental conditions. Long-lived triplet or singlet excited electronic states have the potential to cause photodamage, particularly in the presence of oxygen, and so a variety of mechanisms exist to prevent formation of such states or safely dissipate their energy. Here, we report a dramatic difference in spectral evolution in fully reduced and partially oxidized Rhodobacter sphaeroides reaction centres (RCs) following excitation of the monomeric bacteriochlorophyll (BChl) cofactors at 805 nm...
September 26, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Xiaoqiang Ma, Hong Liang, Chenxi Ning, Senwen Deng, Erzheng Su
Herein, we reported that Rhodobacter sphaeroides (R. sphaeroides) can be engineered by heterologous expression of an alcohol dehydrogenase (adh) from Leifsonia sp. to build a light-driven cofactor regeneration system for synthesis of chiral alcohol. The model substrate, 3'-chloroacetophenone, can be reduced by the engineered R. sphaeroides to (R)-1-(3-chlorophenyl) ethanol with an enantiomeric excess (e.e.) value of more than 99% in an n-hexane/aqueous biphasic media. This system, which is fully controlled by light, exhibited potential power to be an alternative cofactor regeneration platform for cheap synthesis of various chiral alcohols via the cloning other oxidoreductases with diverse characteristics...
July 29, 2017: Journal of Biotechnology
Luis Pereira, Ivo H Saraiva, A Sofia F Oliveira, Cláudio M Soares, Ricardo O Louro, Carlos Frazão
The ancient metabolism of photoferrotrophy is likely to have played a key role in the biogeochemical cycle of iron on Early Earth leading to the deposition of Banded Iron Formations prior to the emergence of oxygenic photosynthesis. Extant organisms still performing this metabolism provide a convenient window to peer into its molecular mechanisms. Here we report the molecular structure of FoxE, the putative terminal iron oxidase of Rhodobacter ferrooxidans SW2. This protein is organized as a trimer with two hemes and a disulfide bridge per monomer...
July 29, 2017: Biochimica et Biophysica Acta
David J K Swainsbury, Stefan Scheidelaar, Nicholas Foster, Rienk van Grondelle, J Antoinette Killian, Michael R Jones
Solubilisation of biological lipid bilayer membranes for analysis of their protein complement has traditionally been carried out using detergents, but there is increasing interest in the use of amphiphilic copolymers such as styrene maleic acid (SMA) for the solubilisation, purification and characterisation of integral membrane proteins in the form of protein/lipid nanodiscs. Here we survey the effectiveness of various commercially-available formulations of the SMA copolymer in solubilising Rhodobacter sphaeroides reaction centres (RCs) from photosynthetic membranes...
October 2017: Biochimica et Biophysica Acta
Rong She, Tong-Tong Li, Dan Luo, Jia-Bao Li, Liu-Yi Yin, Huan Li, Yao-Min Liu, Xiang-Zhen Li, Qi-Gui Yan
Gut microbiota are integral to the host, and have received increased attention in recent years. However, information regarding the intestinal microbiota of many aquaculture animals is insufficient; elucidating the dynamics of the intestinal microbiota can be beneficial for nutrition, immunity, and disease control. In this study, we used 16S rRNA sequencing to observe changes in the intestinal microbiota of gibel carp (Carassius auratus gibelio) associated with cyprinid herpesvirus 2 (CyHV-2) infection. Our results indicate that the diversity of the intestinal microbiota was strongly reduced, and the composition was dramatically altered following CyHV-2 infection...
July 26, 2017: Current Microbiology
Marija Najdanova, Daniel Gräsing, A Alia, Jörg Matysik
The origin of the functional symmetry break in bacterial photosynthesis challenges since several decades. Although structurally very similar, the two branches of cofactors in the reaction center (RC) protein complex act very differently. Upon photochemical excitation, an electron is transported along one branch, while the other remains inactive. Photochemically induced dynamic nuclear polarization (photo-CIDNP) magic-angle spinning (MAS) (13) C NMR revealed that the two bacteriochlorophyll cofactors forming the "Special Pair" donor dimer are already well distinguished in the electronic ground-state...
July 26, 2017: Photochemistry and Photobiology
Christopher W Jones, Judith P Armitage
Bacterial chemosensory proteins form large hexagonal arrays. Several key features of chemotactic signaling depend on these large arrays, namely, cooperativity between receptors, sensitivity, integration of different signals, and adaptation. The best-studied arrays are the membrane-associated arrays found in most bacteria. Rhodobacter sphaeroides has two spatially distinct chemosensory arrays, one is transmembrane and the other is cytoplasmic. These two arrays work together to control a single flagellum. Deletion of one of the soluble chemoreceptors, TlpT, results in the loss of the formation of the cytoplasmic array...
October 1, 2017: Journal of Bacteriology
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