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Mingxu Fang, Carl E Bauer
Purple nonsulfur bacteria adapt their physiology to a wide variety of environmental conditions often through the control of transcription. One of the main transcription factors involved in controlling expression of the Rhodobacter capsulatus photosystem is CrtJ, which functions as an aerobic repressor of photosystem genes. Recently, we reported that a vitamin B12 binding antirepressor of CrtJ called AerR is required for anaerobic expression of the photosystem. However, the mechanism whereby AerR regulates CrtJ activity is unclear...
March 21, 2017: MBio
Andrew Hitchcock, C Neil Hunter, Melih Sener
Cell doubling times of the purple bacterium Rhodobacter sphaeroides during photosynthetic growth are determined experimentally and computationally as a function of illumination. For this purpose, energy conversion processes in an intracytoplasmic membrane vesicle, the chromatophore, are described based on an atomic detail structural model. The cell doubling time and its illumination dependence are computed in terms of the return-on-investment (ROI) time of the chromatophore, determined computationally from the ATP production rate, and the mass ratio of chromatophores in the cell, determined experimentally from whole cell absorbance spectra...
March 16, 2017: Journal of Physical Chemistry. B
Marc P Grüll, Lourdes Peña-Castillo, Martin E Mulligan, Andrew S Lang
Small non-coding RNAs (sRNAs) are involved in the control of numerous cellular processes through various regulatory mechanisms, and in the past decade many studies have identified sRNAs in a multitude of bacterial species using RNA sequencing (RNA-seq). Here, we present the first genome-wide analysis of sRNA sequencing data in Rhodobacter capsulatus, a purple nonsulfur photosynthetic alphaproteobacterium. Using a recently developed bioinformatics approach, sRNA-Detect, we detected 422 putative sRNAs from R...
March 15, 2017: RNA Biology
Fatthy Mohamed Morsy
This study investigated synergistic dark and photo-fermentation using continuous fermentation system (CFS). The system relies on connecting several fermenters from bottom of one to top culture level of the next in a manner that allows for delaying movement of the substrate and thus for its full consumption. While H2 was collected, CFS allowed for moving liquid byproducts toward the outlet and hence continuous productivity. CFS could be efficiently used for: (1) Continuous dark and photo-fermentation H2 production by Clostridiumacetobutylicum and Rhodobacter capsulatus producing 5...
February 21, 2017: Journal of Photochemistry and Photobiology. B, Biology
Antony R Crofts, Stuart W Rose, Rodney L Burton, Amit V Desai, Paul J A Kenis, Sergei A Dikanov
The Q-cycle mechanism of the bc1 complex is now well enough understood to allow application of advanced computational approaches to the study of atomistic processes. In addition to the main features of the mechanism, these include control and gating of the bifurcated reaction at the Qo-site, through which generation of damaging reactive oxygen species is minimized. We report a new molecular dynamics model of the Rhodobacter sphaeroides bc1 complex implemented in a native membrane, and constructed so as to eliminate blemishes apparent in earlier Rhodobacter models...
March 14, 2017: Journal of Physical Chemistry. B
Takayuki Shimizu, Jiangchuan Shen, Mingxu Fang, Yixiang Zhang, Koichi Hori, Jonathan C Trinidad, Carl E Bauer, David P Giedroc, Shinji Masuda
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 functions as a master regulator of sulfide-dependent gene expression in the purple photosynthetic bacterium Rhodobacter capsulatus SqrR has three cysteine residues, two of which, C41 and C107, are conserved in SqrR homologs from other bacteria...
February 28, 2017: Proceedings of the National Academy of Sciences of the United States of America
Javier M González, Ricardo Marti-Arbona, Julian C H Chen, Clifford J Unkefer
Malyl-CoA lyase (MCL) is an Mg(2+)-dependent enzyme that catalyzes the reversible cleavage of (2S)-4-malyl-CoA to yield acetyl-CoA and glyoxylate. MCL enzymes, which are found in a variety of bacteria, are members of the citrate lyase-like family and are involved in the assimilation of one- and two-carbon compounds. Here, the 1.56 Å resolution X-ray crystal structure of MCL from Methylobacterium extorquens AM1 with bound Mg(2+) is presented. Structural alignment with the closely related Rhodobacter sphaeroides malyl-CoA lyase complexed with Mg(2+), oxalate and CoA allows a detailed analysis of the domain motion of the enzyme caused by substrate binding...
February 1, 2017: Acta Crystallographica. Section F, Structural Biology Communications
Stefan Reschke, Stefan Mebs, Kajsa G V Sigfridsson-Clauss, Ramona Kositzki, Silke Leimkühler, Michael Haumann
Enzymes of the xanthine oxidase family are among the best characterized mononuclear molybdenum enzymes. Open questions about their mechanism of transfer of an oxygen atom to the substrate remain. The enzymes share a molybdenum cofactor (Moco) with the metal ion binding a molybdopterin (MPT) molecule via its dithiolene function and terminal sulfur and oxygen groups. For xanthine dehydrogenase (XDH) from the bacterium Rhodobacter capsulatus, we used X-ray absorption spectroscopy to determine the Mo site structure, its changes in a pH range of 5-10, and the influence of amino acids (Glu730 and Gln179) close to Moco in wild-type (WT), Q179A, and E730A variants, complemented by enzyme kinetics and quantum chemical studies...
February 20, 2017: Inorganic Chemistry
Hyunmin Koo, Joseph A Hakim, Mickie L Powell, Ranjit Kumar, Peter G Eipers, Casey D Morrow, Michael Crowley, Elliot J Lefkowitz, Stephen A Watts, Asim K Bej
In this study, we report the gut microbial composition and predictive functional profiles of zebrafish, Danio rerio, fed with a control formulated diet (CFD), and a gluten formulated diet (GFD) using a metagenomics approach and bioinformatics tools. The microbial communities of the GFD-fed D. rerio displayed heightened abundances of Legionellales, Rhizobiaceae, and Rhodobacter, as compared to the CFD-fed counterparts. Predicted metagenomics of microbial communities (PICRUSt) in GFD-fed D. rerio showed KEGG functional categories corresponding to bile secretion, secondary bile acid biosynthesis, and the metabolism of glycine, serine, and threonine...
February 3, 2017: Journal of Microbiological Methods
Wei Wei, Tong Liu, Xinfeng Li, Ruofan Wang, Wei Zhao, Guoping Zhao, Shimin Zhao, Zhihua Zhou
The metabolism of the purple non-sulfur bacterium Rhodobacter sphaeroides is versatile and it can grow under various conditions. Here, we report evidence that the anaerobic photosynthetic metabolism of R. sphaeroides is regulated by protein lysine acetylation. Using a proteomic approach, 59 acetylated peptides were detected. Among them is the global anaerobic transcription factor FnrL, which regulates the biosynthetic pathway of tetrapyrroles and synthesis of the photosynthetic apparatus. Lysine 223 of FnrL was identified as acetylated...
January 24, 2017: Molecular Microbiology
Sebastià Puig, Ramon Ganigué, Pau Batlle-Vilanova, M Dolors Balaguer, Lluís Bañeras, Jesús Colprim
This study reveals that reduction of carbon dioxide (CO2) to commodity chemicals can be functionally compartmentalized in bioelectrochemical systems. In the present example, a syntrophic consortium composed by H2-producers (Rhodobacter sp.) in the biofilm is combined with carboxidotrophic Clostridium species, mainly found in the bulk liquid. The performance of these H2-mediated electricity-driven systems could be tracked by the activity of a biological H2 sensory protein identified at cathode potentials between -0...
March 2017: Bioresource Technology
Vincenzo Luongo, Anish Ghimire, Luigi Frunzo, Massimiliano Fabbricino, Giuseppe d'Antonio, Francesco Pirozzi, Giovanni Esposito
The aim of this work is to investigate the hydrogen and poly-β-hydroxybutyrate (PHB) production during the photofermentative treatment of the effluent from a dark fermentation reactor fed with the organic fraction of municipal solid waste. Two different inocula, an adapted culture of Rhodobacter sphaeroides AV1b and a mixed consortium of purple non sulphur bacteria have been investigated under the same operational conditions. Different hydrogen productivities of 364 and 559NmL H2 L(-1) were observed for the Rhodobacter sphaeroides and the mixed culture consortium tests, respectively: the consortium of PNSB resulted 1...
March 2017: Bioresource Technology
Katie J Grayson, Kaitlyn M Faries, Xia Huang, Pu Qian, Preston Dilbeck, Elizabeth C Martin, Andrew Hitchcock, Cvetelin Vasilev, Jonathan M Yuen, Dariusz M Niedzwiedzki, Graham J Leggett, Dewey Holten, Christine Kirmaier, C Neil Hunter
Photosynthesis uses a limited range of the solar spectrum, so enhancing spectral coverage could improve the efficiency of light capture. Here, we show that a hybrid reaction centre (RC)/yellow fluorescent protein (YFP) complex accelerates photosynthetic growth in the bacterium Rhodobacter sphaeroides. The structure of the RC/YFP-light-harvesting 1 (LH1) complex shows the position of YFP attachment to the RC-H subunit, on the cytoplasmic side of the RC complex. Fluorescence lifetime microscopy of whole cells and ultrafast transient absorption spectroscopy of purified RC/YFP complexes show that the YFP-RC intermolecular distance and spectral overlap between the emission of YFP and the visible-region (QX) absorption bands of the RC allow energy transfer via a Förster mechanism, with an efficiency of 40±10%...
January 5, 2017: Nature Communications
S Bhaduri, V Stadnytskyi, S D Zakharov, S Saif Hasan, Ł Bujnowicz, M Sarewicz, S Savikhin, A Osyczka, W A Cramer
The intramembrane cytochrome bc1 complex of the photosynthetic bacterium Rhodobacter capsulatus and the cytochrome b6f complex, which functions in oxygenic photosynthesis, utilize two pairs of b-hemes in a symmetric dimer to accomplish proton-coupled electron transfer. The transmembrane electron transfer pathway in each complex was identified through the novel use of heme Soret band excitonic circular dichroism (CD) spectra, for which the responsible heme-heme interactions were determined from crystal structures...
February 9, 2017: Journal of Physical Chemistry. B
Virginia Montiel Corona, Sylvie Le Borgne, Sergio Revah, Marcia Morales
A Rhodobacter capsulatus strain and a photoheterotrophic culture (IZT) were cultivated to produce hydrogen under different light-dark cycles. A dark fermentation effluent (DFE) was used as substrate. It was found that IZT culture had an average cumulative hydrogen production (Paccum H2) of 1300±43mLH2L(-1) under continuous illumination and light-dark cycles of 30 or 60min. In contrast, R. capsulatus reduced its Paccum H2 by 20% under 30:30min light-dark cycles, but tripled its poly-β-hydroxybutyrate (PHB) content (308±2mgPHB gdw(-1)) compared to continuous illumination...
February 2017: Bioresource Technology
Matt S A Wecker, Stephen E Beaton, Robert A Chado, Maria L Ghirardi
The cover image, by Maria L. Ghirardi et al., is based on the Article Development of a Rhodobacter capsulatus self-reporting model system for optimizing light-dependent, [FeFe]-hydrogenase-driven H2 production, DOI: 10.1002/bit.26076.
February 2017: Biotechnology and Bioengineering
Kamal Elkahlout, Siamak Alipour, Inci Eroglu, Ufuk Gunduz, Meral Yucel
In this study, agar immobilization technique was employed for biological hydrogen production using Rhodobacter capsulatus DSM 1710 (wild type) and YO3 (hup-mutant) strains in sequential batch process. Different agar and glutamate concentrations were tested with defined nutrient medium. Agar concentration 4% (w/v) and 4 mM glutamate were selected for bacterial immobilization in terms of rate and longevity of hydrogen production. Acetate concentration was increased from 40 to 60-100 and 60 mM gave best results with both bacterial strains immobilized in 4% (w/v) agar...
April 2017: Bioprocess and Biosystems Engineering
Hongju Ma, Fan Zhang, Elisabeth Ignatz, Martin Suehnel, Peng Xue, Patrick Scheerer, LarsOliver Essen, Norbert Krauß, Tilman Lamparter
The (6-4) photolyases of the FeS-BCP group can be considered as the most ancient type among the large family of cryptochrome and photolyase flavoproteins. In contrast to other photolyases they contain an Fe-S cluster of unknown function, a DMRL chromophore, an interdomain loop which could interact with DNA, and a long C-terminal extension. We compared DNA repair and photoreduction of two members of the FeS-BCP family, Agrobacterium fabrum PhrB and Rhodobacter sphaeroides RsCryB, with a eukaryotic (6-4) photolyase from Ostreococcus, OsCPF, and a member of the class III CPD photolyases, PhrA from A...
December 19, 2016: Photochemistry and Photobiology
Jonathan Lo, Daniel G Olson, Sean Jean-Loup Murphy, Liang Tian, Shuen Hon, Anthony Lanahan, Adam M Guss, Lee R Lynd
The NfnAB (NADH-dependent reduced ferredoxin: NADP(+) oxidoreductase) and Rnf (ion-translocating reduced ferredoxin: NAD(+) oxidoreductase) complexes are thought to catalyze electron transfer between reduced ferredoxin and NAD(P)(+). Efficient electron flux is critical for engineering fuel production pathways, but little is known about the relative importance of these enzymes in vivo. In this study we investigate the importance of the NfnAB and Rnf complexes in Clostridium thermocellum for growth on cellobiose and Avicel using gene deletion, enzyme assays, and fermentation product analysis...
January 2017: Metabolic Engineering
José Hernandez-Valle, Clelia Domenzain, Javier de la Mora, Sebastian Poggio, Georges Dreyfus, Laura Camarena
Rhodobacter sphaeroides is an alphaproteobacterium that has two complete sets of flagellar genes. The fla1 set was acquired by horizontal transfer from an ancestral gammaproteobacterium and is the only set of flagellar genes that is expressed during growth under standard laboratory conditions. The products of these genes assemble a single, subpolar flagellum. In the absence of the Fla1 flagellum, a gain-of-function mutation in the histidine kinase CckA turns on the expression of the fla2 flagellar genes through the response regulator CtrA...
March 1, 2017: Journal of Bacteriology
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