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https://www.readbyqxmd.com/read/28644830/optimal-chemotactic-responses-in-stochastic-environments
#1
Martin Godány, Bhavin S Khatri, Richard A Goldstein
Although the "adaptive" strategy used by Escherichia coli has dominated our understanding of bacterial chemotaxis, the environmental conditions under which this strategy emerged is still poorly understood. In this work, we study the performance of various chemotactic strategies under a range of stochastic time- and space-varying attractant distributions in silico. We describe a novel "speculator" response in which the bacterium compare the current attractant concentration to the long-term average; if it is higher then they tumble persistently, while if it is lower than the average, bacteria swim away in search of more favorable conditions...
2017: PloS One
https://www.readbyqxmd.com/read/28634761/unveiling-the-compositional-variety-of-cardiolipins-in-rhodobacter-sphaeroides-by-liquid-chromatography-with-electrospray-ionization-and-multistage-collision-induced-dissociation-mass-spectrometry
#2
Sara Granafei, Ilario Losito, Massimo Trotta, Angela Agostiano, Francesco Palmisano, Tommaso R I Cataldi
Cardiolipins (CL) contained in the lipid extracts of the photosynthetic bacterium Rhodobacter sphaeroides (strain R26) were systematically characterized by reversed-phase liquid chromatography coupled to electrospray ionization mass spectrometry, performed in single (MS), tandem (MS/MS) and sequential (MS(3)) modes using a linear ion trap mass spectrometer. The total number of carbon atoms and C=C bonds of each CL and, subsequently, those related to each of the constituting phosphatidic acid (PA) units, along with the location of the latter on the central glycerol backbone, were inferred from MS and MS/MS data, respectively...
June 20, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28634234/the-thioreduction-component-ccmg-confers-efficiency-and-the-heme-ligation-component-ccmh-ensures-stereo-specificity-during-cytochrome-c-maturation
#3
Andreia F Verisssimo, Bahia Khalfaoui-Hassani, Josephine Hwang, Stefan Steimle, Nur Selamoglu, Carsten Sanders, Camilo Khatchikian, Fevzi Daldal
In many Gram-negative bacteria, including Rhodobacter capsulatus, cytochrome c maturation (Ccm) is carried out by a membrane-integral machinery composed of nine proteins (CcmA to I). During this process, the periplasmic thiol-disulfide oxidoreductase DsbA is thought to catalyze the formation of a disulfide bond between the Cys residues at the apocytochrome c heme binding site (CXXCH). Subsequently, a Ccm-specific thioreductive pathway involving CcmG and CcmH reduces this disulfide bond to allow covalent heme ligation...
June 20, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28633072/roles-of-serum-in-innate-immune-responses-of-human-leukocytes-to-synthetic-lipopeptide
#4
Terukazu Sanui, Masaaki Takeshita, Takao Fukuda, Urara Tanaka, Rehab Alshargabi, Yoshitomi Aida, Fusanori Nishimura
Tripalmitoyl-S-glyceryl-l-Cys-Ser-(Lys)4 (Pam3CSK4) is a highly conserved molecular motif found in various classes of lipoproteins. The requirement for leukocyte to respond to synthetic Pam3CSK4 were studied. Pam3CSK4 primed neutrophils for a respiratory burst in a serum-dependent manner. Pam3CSK4 upregulated CD11b, CD14, and cytochrome b558, and downregulated Leu-8. Treatment of neutrophils with anti-CD14 antibodies and treatment of serum with anti-LPS binding protein (LBP) antibodies resulted in the inhibition of priming for respiratory burst by Pam3CSK4...
June 17, 2017: International Immunopharmacology
https://www.readbyqxmd.com/read/28617267/removal-of-cadmium-and-zinc-from-contaminated-wastewater-using-rhodobacter-sphaeroides
#5
Xiaomin Li, Weihua Peng, Yingying Jia, Lin Lu, Wenhong Fan
Rhodobacter sphaeroides was used for bioremediation of wastewater polluted with cadmium (Cd) and zinc (Zn). The tolerance of the microorganism to selected heavy metals (HMs), as well as the effects of pH, temperature and inoculum size on the removal rate, was investigated. The remediation effects of R. sphaeroides were analysed at different initial concentrations of HMs. Bioremediation mechanisms were thoroughly discussed based on the results from the cell characterisation analysis. Cd and Zn could inhibit the growth of R...
June 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/28610971/metabolic-engineering-of-escherichia-coli-cell-factory-for-highly-active-xanthine-dehydrogenase-production
#6
Cheng-Hua Wang, Chong Zhang, Xin-Hui Xing
The aim of this work was to demonstrate the first proof-of-concept for the use of ab initio-aided assembly strategy intensifying in vivo biosynthesis process to construct Escherichia coli cell factory overproducing highly active xanthine dehydrogenase (XDH). Three global regulator (IscS, TusA and NarJ) and four chaperone proteins (DsbA, DsbB, NifS and XdhC) were overexpressed to aid the formation and ordered assembly of three redox center cofactors of Rhodobacter capsulatus XDH in E. coli. The NifS, IscS and DsbB enhanced the specific activity of RcXDH by 30%, 94% and 49%, respectively...
May 31, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28605596/mechanism-of-triplet-energy-transfer-in-photosynthetic-bacterial-reaction-centers
#7
Sarthak Mandal, Anne-Marie Carey, Joshua Locsin, Bing-Rong Gao, JoAnn C Williams, James P Allen, Su Lin, Neal W Woodbury
In purple bacterial reaction centers, triplet excitation energy transfer occurs from the primary donor P, a bacteriochlorophyll dimer, to a neighboring carotenoid to prevent photodamage from the generation of reactive oxygen species. The BB bacteriochlorophyll molecule that lies between P and the carotenoid on the inactive electron transfer branch is involved in triplet energy transfer between P and the carotenoid. To expand the high-resolution spectral and kinetic information available for describing the mechanism, we investigated the triplet excited state formation and energy transfer pathways in the reaction center of Rhodobacter sphaeroides using pump-probe transient absorption spectroscopy over a broad spectral region on the nanosecond to microsecond timescale at both room temperature and at 77 K...
June 12, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28601078/an-alternative-pathway-of-light-induced-transmembrane-electron-transfer-in-photosynthetic-reaction-centers-of-rhodobacter-sphaeroides
#8
R A Khatypov, A M Khristin, T Yu Fufina, V A Shuvalov
In the absorption spectrum of Rhodobacter sphaeroides reaction centers, a minor absorption band was found with a maximum at 1053 nm. The amplitude of this band is ~10,000 times less and its half-width is comparable to that of the long-wavelength absorption band of the primary electron donor P870. When the primary electron donor is excited by femtosecond light pulses at 870 nm, the absorption band at 1053 nm is increased manifold during the earliest stages of charge separation. The growth of this absorption band in difference absorption spectra precedes the appearance of stimulated emission at 935 nm and the appearance of the absorption band of anion-radical BA(-) at 1020 nm, reported earlier by several researchers...
June 2017: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/28601069/acetate-metabolism-in-the-purple-non-sulfur-bacterium-rhodobacter-capsulatus
#9
E P Petushkova, A A Tsygankov
The purple non-sulfur bacterium Rhodobacter capsulatus B10 can grow on acetate as the sole carbon source under photoheterotrophic conditions. It is known that the bacterium can use the glyoxylate cycle and, in addition to it, or alternatively to it, an unknown pathway for acetate assimilation. We analyzed the genetic potential for functioning of additional metabolic pathways of oxaloacetic acid (OAA) pool replenishment in R. capsulatus. Using published microarray data of more than 4000 transcripts of genes for R...
May 2017: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/28599143/guaranteeing-a-captive-audience-coordinated-regulation-of-gene-transfer-agent-gta-production-and-recipient-capability-by-cellular-regulators
#10
REVIEW
Alexander B Westbye, J Thomas Beatty, Andrew S Lang
Gene transfer agents (GTAs) are bacteriophage-like particles produced by many prokaryotes. Several members of the Alphaproteobacteria produce a class of genetically-related GTAs that is best studied in Rhodobacter capsulatus. DNA transfer by the R. capsulatus GTA (RcGTA) combines aspects of both transduction and natural transformation, as recipient cells require a natural transformation-like system to incorporate donated DNA. The genes involved in RcGTA production and recipient capability are located at multiple loci in the bacterial genome; however, a conserved phosphorelay containing the response regulator CtrA and a quorum sensing system regulate both RcGTA production and recipient capability...
June 6, 2017: Current Opinion in Microbiology
https://www.readbyqxmd.com/read/28587931/the-c-terminus-of-pufx-plays-a-key-role-in-dimerisation-and-assembly-of-the-reaction-center-light-harvesting-1-complex-from-rhodobacter-sphaeroides
#11
Pu Qian, Elizabeth C Martin, Irene W Ng, C Neil Hunter
In bacterial photosynthesis reaction center-light-harvesting 1 (RC-LH1) complexes trap absorbed solar energy by generating a charge separated state. Subsequent electron and proton transfers form a quinol, destined to diffuse to the cytochrome bc1 complex. In bacteria such as Rhodobacter (Rba.) sphaeroides and Rba. capsulatus the PufX polypeptide creates a channel for quinone/quinol traffic across the LH1 complex that surrounds the RC, and it is therefore essential for photosynthetic growth. PufX also plays a key role in dimerization of the RC-LH1-PufX core complex, and the structure of the Rba...
June 3, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28540587/removal-of-the-h-subunit-results-in-enhanced-exposure-of-the-semiquinone-sites-in-the-lm-dimer-from-rhodobacter-sphaeroides-to-oxidation-by-ferricyanide-and-by-o2
#12
Chang Sun
Bacterial reaction centers (RC) from Rhodobacter sphaeroides have been widely used to functionalize electrodes and to generate photocurrent. However, in most studies, direct electron transfer from the semiquinone to the electrode was not observed because the H subunit of the RC shields the semiquinone. It is demonstrated in the current work that removal of the H subunit effectively exposes the semiquinone sites in the LM dimer. This is demonstrated by measuring the second-order rate constant for the reaction between ferricyanide and the anionic semiquinone Q A(-) formed by an actinic flash...
May 24, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28536938/enhancement-of-5-aminolevulinic-acid-production-by-metabolic-engineering-of-the-glycine-biosynthesis-pathway-in-corynebacterium-glutamicum
#13
Yalan Zou, Tao Chen, Lili Feng, Shuanghong Zhang, Dongxu Xing, Zhiwen Wang
OBJECTIVE: To construct a strain of Corynebacterium glutamicum capable of efficiently producing 5-aminolevulinic acid (5-ALA) via the C4 pathway by modification of serine and glycine pathway using glucose as sole carbon source. RESULTS: The recombinant C. glutamicum strain AP2 harboring a codon-optimized hemA gene from Rhodobacter sphaeroides was used as host strain for 5-ALA production. A plasmid harboring the serine operon, which contained serB, serC and the site-specific mutant serA (Δ197) , was constructed and introduced into C...
May 23, 2017: Biotechnology Letters
https://www.readbyqxmd.com/read/28536286/mutations-that-alter-the-bacterial-cell-envelope-increase-lipid-production
#14
Kimberly C Lemmer, Weiping Zhang, Samantha J Langer, Alice C Dohnalkova, Dehong Hu, Rachelle A Lemke, Jeff S Piotrowski, Galya Orr, Daniel R Noguera, Timothy J Donohue
Lipids from microbes offer a promising source of renewable alternatives to petroleum-derived compounds. In particular, oleaginous microbes are of interest because they accumulate a large fraction of their biomass as lipids. In this study, we analyzed genetic changes that alter lipid accumulation in Rhodobacter sphaeroides By screening an R. sphaeroides Tn5 mutant library for insertions that increased fatty acid content, we identified 10 high-lipid (HL) mutants for further characterization. These HL mutants exhibited increased sensitivity to drugs that target the bacterial cell envelope and changes in shape, and some had the ability to secrete lipids, with two HL mutants accumulating ~60% of their total lipids extracellularly...
May 23, 2017: MBio
https://www.readbyqxmd.com/read/28528494/carotenoid-to-bacteriochlorophyll-energy-transfer-in-the-rc-lh1-pufx-complex-from-rhodobacter-sphaeroides-containing-the-extended-conjugation-keto-carotenoid-diketospirilloxanthin
#15
Václav Šlouf, Gürkan Keşan, Radek Litvín, David J K Swainsbury, Elizabeth C Martin, C Neil Hunter, Tomáš Polívka
RC-LH1-PufX complexes from a genetically modified strain of Rhodobacter sphaeroides that accumulates carotenoids with very long conjugation were studied by ultrafast transient absorption spectroscopy. The complexes predominantly bind the carotenoid diketospirilloxanthin, constituting about 75% of the total carotenoids, which has 13 conjugated C=C bonds, and the conjugation is further extended to two terminal keto groups. Excitation of diketospirilloxanthin in the RC-LH1-PufX complex demonstrates fully functional energy transfer from diketospirilloxanthin to BChl a in the LH1 antenna...
May 20, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28507242/an-rpohi-dependent-response-promotes-outgrowth-after-extended-stationary-phase-in-the-alphaproteobacterium-rhodobacter-sphaeroides
#16
B Remes, T Rische-Grahl, K M H Müller, K U Förstner, Y Sung-Huan, L Weber, A Jäger, V Peuser, G Klug
Under unfavorable growth conditions, bacteria enter stationary phase and can maintain cell viability over prolonged periods with no increase in cell number. To get insights into the regulatory mechanisms that allow bacteria to resume growth when conditions become favorable again (outgrowth) we performed global transcriptome analyses at different stages of growth for the alphaproteobacterium Rhodobacter sphaeroides The majority of genes was not differentially expressed across growth phases. After short stationary phase (about 20 h after growth starts to slow down), only 7 % of the genes showed altered expression (fold change of > 1...
May 15, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28497282/highly-complex-substrates-lead-to-dynamic-bacterial-community-for-polyhydroxyalkanoates-production
#17
Diogo Queirós, Alexandre Fonseca, Simona Rossetti, Luísa S Serafim, Paulo C Lemos
Mixed microbial cultures (MMC) and waste/surplus substrates, as hardwood spent sulfite liquor, are being used to decrease polyhydroxyalkanoates' (PHA) production costs. The process involves two or three steps, being the selection step a crucial one. For the industrial implementation of this strategy, reactor stability in terms of both performance and microbial community presence has to be considered. A long-term operation of a sequencing batch reactor under feast/famine conditions was performed along with microbial community identification/quantification using FISH and DGGE...
May 11, 2017: Journal of Industrial Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28471051/a-presumed-antagonistic-lps-identifies-distinct-functional-organization-of-tlr4-in-mouse-microglia
#18
Christin Döring, Tommy Regen, Ulla Gertig, Denise van Rossum, Anne Winkler, Nasrin Saiepour, Wolfgang Brück, Uwe-Karsten Hanisch, Hana Janova
Microglia as principle innate immune cells of the central nervous system (CNS) are the first line of defense against invading pathogens. They are capable of sensing infections through diverse receptors, such as Toll-like receptor 4 (TLR4). This receptor is best known for its ability to recognize bacterial lipopolysaccharide (LPS), a causative agent of gram-negative sepsis and septic shock. A putative, naturally occurring antagonist of TLR4 derives from the photosynthetic bacterium Rhodobacter sphaeroides. However, the antagonistic potential of R...
May 4, 2017: Glia
https://www.readbyqxmd.com/read/28469140/mitochondria-targeted-antioxidants-as-highly-effective-antibiotics
#19
Pavel A Nazarov, Ilya A Osterman, Artem V Tokarchuk, Marina V Karakozova, Galina A Korshunova, Konstantin G Lyamzaev, Maxim V Skulachev, Elena A Kotova, Vladimir P Skulachev, Yuri N Antonenko
Mitochondria-targeted antioxidants are known to alleviate mitochondrial oxidative damage that is associated with a variety of diseases. Here, we showed that SkQ1, a decyltriphenyl phosphonium cation conjugated to a quinone moiety, exhibited strong antibacterial activity towards Gram-positive Bacillus subtilis, Mycobacterium sp. and Staphylococcus aureus and Gram-negative Photobacterium phosphoreum and Rhodobacter sphaeroides in submicromolar and micromolar concentrations. SkQ1 exhibited less antibiotic activity towards Escherichia coli due to the presence of the highly effective multidrug resistance pump AcrAB-TolC...
May 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28465227/bovine-lactoferrin-reduces-extra-territorial-facial-allodynia-hyperalgesia-following-a-trigeminal-nerve-injury-in-the-rat
#20
Kayo Horie, Mineo Watanabe, Chea Chanbora, Tetsuya Awada, Ryo Kunimatsu, Takashi Uchida, Takashi Takata, Kotaro Tanimoto
There is an urgent clinical need for an effective therapeutic agent to treat neuropathic pain. This study explored whether intrathecal administration of bovine lactoferrin (bLF), in combination with signal transduction pathway inhibition or an inflammatory cytokine production, results in reduced allodynia/hyperalgesia in the whisker pad area following mental nerve transection (MNT) in rats. Rats were intrathecally infused with bLF, lipopolysaccharide from Rhodobacter sphaeroides (LPS-RS), an antagonist of Toll-like receptor 4 (TLR4), or interleukin (IL)-18 binding protein (BP)...
April 29, 2017: Brain Research
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