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https://www.readbyqxmd.com/read/29150636/a-genetic-system-for-targeted-mutations-to-disrupt-and-restore-genes-in-the-obligate-bacterium-ehrlichia-chaffeensis
#1
Ying Wang, Lanjing Wei, Huitao Liu, Chuanmin Cheng, Roman R Ganta
Obligate intracellular bacteria (obligates) belonging to Rickettsiales and Chlamydiales cause diseases in hundreds of millions of people worldwide and in many animal species. Lack of an efficient system for targeted mutagenesis in obligates remains a major impediment in understanding microbial pathogenesis. Challenges in creating targeted mutations may be attributed to essential nature of majority of the genes and intracellular replication dependence. Despite success in generating random mutations, a method that works well in creating mutations in specific genes of interest followed by complementation remains problematic for obligates and is a highly sought-after goal...
November 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29150515/loop-of-streptomyces-feruloyl-esterase-plays-an-important-role-in-its-activity-of-releasing-ferulic-acid-from-biomass
#2
Misugi Uraji, Haruka Tamura, Eiichi Mizohata, Jiro Arima, Kun Wan, Ken'ichi Ogawa, Tsuyoshi Inoue, Tadashi Hatanaka
Feruloyl esterases (FAEs) are key enzymes required for the production of ferulic acid from agricultural biomass. Previously, we identified and characterized R18, an FAE from Streptomyces cinnamoneus NBRC 12852, which showed no sequence similarity with the known FAEs. To determine the region involved in its catalytic activity, we constructed chimeric enzymes using R18 and its homolog (TH2-18) from S. cinnamoneus strain TH-2. Although R18 and TH2-18 showed 74% identity in their primary sequence, the recombinant proteins of these two FAEs (rR18 and rTH2-18) showed very different specific activities toward ethyl ferulate...
November 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29150508/community-composition-and-ultrastructure-of-a-nitrate-dependent-anaerobic-methane-oxidizing-enrichment-culture
#3
Lavinia Gambelli, Simon Guerrero-Cruz, Rob J Mesman, Geert Cremers, Mike S M Jetten, Huub J M Op den Camp, Boran Kartal, Claudia Lueke, Laura van Niftrik
Methane is a very potent greenhouse gas and can be oxidized aerobically or anaerobically through microbial-mediated processes, thus decreasing methane emissions to the atmosphere. Using a complementary array of methods including phylogenetic analysis, physiological experiments, and light and electron microscopy techniques (including electron tomography), we investigated the community composition and ultrastructure of a continuous bioreactor enrichment culture, in which anaerobic methane oxidation (AOM) was coupled to nitrate reduction...
November 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29150506/the-swinholide-biosynthetic-gene-cluster-from-a-terrestrial-cyanobacterium-nostoc-sp-uhcc-0450
#4
Anu Humisto, Jouni Jokela, Liwei Liu, Matti Wahlsten, Hao Wang, Perttu Permi, João Paulo Machado, Agostinho Antunes, David P Fewer, Kaarina Sivonen
Swinholides are 42-carbon ring polyketides with a twofold axis of symmetry. They are potent cytotoxins that disrupt the actin cytoskeleton. Swinholides were discovered from the marine sponge Theonella sp. and were long-suspected to be produced by symbiotic bacteria. Misakinolide, a structural variant of swinholide, was recently demonstrated to be the product of the symbiotic heterotrophic proteobacterium. Here we report the production of swinholide A by an axenic strain of the terrestrial cyanobacterium Nostoc sp...
November 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29150503/carbon-amendments-alter-microbial-community-structure-and-net-mercury-methylation-potential-in-sediments
#5
Geoff A Christensen, Anil C Somenahally, James G Moberly, Carrie M Miller, Andrew J King, Cynthia C Gilmour, Steven D Brown, Mircea Podar, Craig C Brandt, Scott C Brooks, Anthony V Palumbo, Judy D Wall, Dwayne A Elias
Neurotoxic methylmercury (MeHg) is produced by anaerobic Bacteria and Archaea possessing the genes hgcAB, but it is unknown how organic substrate and electron acceptor availability impact the distribution and abundance of these organisms. We evaluated the impact of organic substrate amendments on mercury (Hg) methylation rates, microbial community structure, and the distribution of hgcAB(+) microbes with sediments. Sediment slurries were amended with short-chain fatty acids, alcohols, or a polysaccharide. Minimal increases in MeHg were observed following lactate, ethanol and methanol amendments while a significant decrease (∼70%) was observed with cellobiose incubations...
November 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29148177/high-concentrations-of-gtp-induce-conformational-changes-in-the-essential-bacterial-gtpase-enga-and-enhance-its-binding-to-the-ribosome
#6
Catarina da Silveira Tomé, Anne-Emmanuelle Foucher, Jean-Michel Jault, Dominique Housset
EngA is a conserved bacterial GTPase involved in ribosome biogenesis. While essential in bacteria, EngA does not have any human ortholog and can thus be an interesting target for new antibacterial compounds. EngA is the only known GTPase bearing two G-domains, making unique its catalytic cycle and the induced modulation of its conformation and interaction with the ribosome. We have investigated nucleotide-induced conformational changes in EngA in order to unveil their role in ribosome binding. SAXS and limited proteolysis were used to probe EngA conformational changes, and revealed a change in protein structure and a distinct rate of proteolysis induced by GTP...
November 17, 2017: FEBS Journal
https://www.readbyqxmd.com/read/29148103/extracytoplasmic-function-sigma-factor-%C3%AF-d-confers-resistance-to-environmental-stress-by-enhancing-mycolate-synthesis-and-modifying-peptidoglycan-structures-in-corynebacterium-glutamicum
#7
Koichi Toyoda, Inui Masayuki
Mycolates are α-branched, β-hydroxylated, long-chain fatty acid specifically synthesized in bacteria in the suborder Corynebacterineae of the phylum Actinobacteria. They form an outer membrane, which functions as a permeability barrier and confers pathogenic mycobacteria to resistance to antibiotics. Although the mycolate biosynthetic pathway has been intensively studied, knowledge of transcriptional regulation of genes involved in this pathway is limited. Here we report that the extracytoplasmic function sigma factor σ(D) is a key regulator of the mycolate synthetic genes in Corynebacterium glutamicum in the suborder...
November 17, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/29147865/changes-of-gut-microbiota-structure-and-morphology-in-weaned-piglets-treated-with-fresh-fermented-soybean-meal
#8
Zhengjun Xie, Luansha Hu, Yuan Li, Shijie Geng, Saisai Cheng, Xiongfeng Fu, Shoumei Zhao, Xinyan Han
This study investigated the effects of dietary fresh fermented soybean meal (FSM) on the intestinal microbiota and metabolites, bacterial enzyme activity and intestinal morphology of weaning piglets. A total of 64 weaned piglets were randomly allocated into two treatments. A corn-soybean-based diet was used as the control and other treatment was fed the same basal diet containing 15% fresh FSM. The feeding trial lasted for 21 days. Bacterial community structure and diversity in the cecum and colon were assessed using pyrosequencing-based analysis...
November 16, 2017: World Journal of Microbiology & Biotechnology
https://www.readbyqxmd.com/read/29147557/the-diversity-and-utility-of-amyloid-fibrils-formed-by-short-amyloidogenic-peptides
#9
REVIEW
Zahraa S Al-Garawi, Kyle L Morris, Karen E Marshall, Jutta Eichler, Louise C Serpell
Amyloidogenic peptides are well known for their involvement in diseases such as type 2 diabetes and Alzheimer's disease. However, more recently, amyloid fibrils have been shown to provide scaffolding and protection as functional materials in a range of organisms from bacteria to humans. These roles highlight the incredible tensile strength of the cross-β amyloid architecture. Many amino acid sequences are able to self-assemble to form amyloid with a cross-β core. Here we describe our recent advances in understanding how sequence contributes to amyloidogenicity and structure...
December 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/29146813/structural-basis-of-bacterial-transcription-activation
#10
Bin Liu, Chuan Hong, Rick K Huang, Zhiheng Yu, Thomas A Steitz
In bacteria, the activation of gene transcription at many promoters is simple and only involves a single activator. The cyclic adenosine 3',5'-monophosphate receptor protein (CAP), a classic activator, is able to activate transcription independently through two different mechanisms. Understanding the class I mechanism requires an intact transcription activation complex (TAC) structure at a high resolution. Here we report a high-resolution cryo-electron microscopy structure of an intact Escherichia coli class I TAC containing a CAP dimer, a σ(70)-RNA polymerase (RNAP) holoenzyme, a complete class I CAP-dependent promoter DNA, and a de novo synthesized RNA oligonucleotide...
November 17, 2017: Science
https://www.readbyqxmd.com/read/29146596/structure-and-function-of-the-leptospira-interrogans-peroxide-stress-regulator-perr-an-atypical-perr-devoid-of-a-structural-metal-binding-site
#11
Mounira Kebouchi, Frederick Saul, Raleb Taher, Annie Landier, Benedicte Beaudeau, Sarah Dubrac, Patrick Weber, Ahmed Haouz, Mathieu Picardeau, Nadia Benaroudj
Peroxide sensing is essential for bacteria survival during aerobic metabolism and host infection. Peroxide stress regulators (PerRs) are homodimeric transcriptional repressors with each monomer typically containing both structural and regulatory metal-binding sites. PerR binding to gene promoters is controlled by the presence of iron in the regulatory site, and iron-catalyzed oxidation of PerR by H2O2 leads to the dissociation of PerR from DNA. In addition to a regulatory metal, most PerRs require a structural metal for proper dimeric assembly...
November 16, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29146531/specific-oxygenation-of-plasma-membrane-phospholipids-by-pseudomonas-aeruginosa-lipoxygenase-induces-structural-and-functional-alterations-in-mammalian-cells
#12
Maceler Aldrovandi, Swathi Banthiya, Sven Meckelmann, You Zhou, Dagmar Heydeck, Valerie B O'Donnell, Hartmut Kuhn
Pseudomonas aeruginosa is a gram-negative pathogen, which causes life-threatening infections in immunocompromized patients. These bacteria express a secreted lipoxygenase (PA-LOX), which oxygenates free arachidonic acid to 15S-hydro(pero)xyeicosatetraenoic acid. It binds phospholipids at its active site and physically interacts with lipid vesicles. When incubated with red blood cells membrane lipids are oxidized and hemolysis is induced but the structures of the oxygenated membrane lipids have not been determined...
November 13, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/29146256/isolation-purification-structural-elucidation-and-antimicrobial-activities-of-kocumarin-a-novel-antibiotic-isolated-from-actinobacterium-kocuria-marina-cmg-s2-associated-with-the-brown-seaweed-pelvetia-canaliculata
#13
Bushra Uzair, Farid Menaa, Barkat Ali Khan, Faryal Vali Mohammad, Viqar Uddin Ahmad, Ryad Djeribi, Bouzid Menaa
AIMS: Screening of seaweed-associated bacteria capable of producing antimicrobials. METHODS AND RESULTS: Fifteen microbial strains, associated to the brown seaweed Pelvetia canaliculata (Linnaeus) attached to the rocks of Sonmiani Beach (Karachi, Pakistan), were screened. Crude extract filtrates of CMG S2 strain grew on Zobell marine agar (ZMA) had the most remarkable antimicrobial activity. Based on its phenotypic aspects (e.g. Gram-positive, microccoid form), biochemical characteristics (e...
January 2018: Microbiological Research
https://www.readbyqxmd.com/read/29145096/sulfaguanidine-cocrystals-synthesis-structural-characterization-and-their-antibacterial-and-hemolytic-analysis
#14
Syed Sibte Asghar Abidi, Yasser Azim, Shahper Nazeer Khan, Asad U Khan
Sulfaguanidine (SG), belongs to the class of sulfonamide drug used as an effective antibiotic. In the present work, using crystal engineering approach two novel cocrystals of SG were synthesized (SG-TBA and SG-PT) with thiobarbutaric acid (TBA) and 1,10-phenanthroline (PT), characterized by solid state techniques viz., powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and the crystal structures were determined by single crystal X-ray diffraction studies...
November 11, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/29145079/microbial-transcript-and-metabolome-analysis-uncover-discrepant-metabolic-pathways-in-autotrophic-and-mixotrophic-anammox-consortia
#15
Ying Feng, Yunpeng Zhao, Yongzhao Guo, Sitong Liu
The ability of anammox bacteria to utilize organic matter has drawn extensive attention. However, the metabolic discrepancies between autotrophic and mixotrophic anammox consortia need to be further explored. Here, microbial transcript and metabolomic analysis were conducted for the samples harvested in the reactors and batch assays to investigate the phenotype discrepancies and intrinsic causes in autotrophic and mixotrophic anammox consortia. Results showed that metabolically active community structures did not show significant difference between autotrophic and mixotrophic anammox consortia (C/N = 0...
October 31, 2017: Water Research
https://www.readbyqxmd.com/read/29144587/characterization-of-complex-heterogeneous-lipid-a-samples-using-hplc-ms-ms-technique-iii-positive-ion-mode-tandem-mass-spectrometry-to-reveal-phosphorylation-and-acylation-patterns-of-lipid-a
#16
Viktor Sándor, Anikó Kilár, Ferenc Kilár, Béla Kocsis, Ágnes Dörnyei
In this study, we report the detailed analysis of the fragmentation patterns of positively charged lipid A species based on their tandem mass spectra obtained under low-energy collision-induced dissociation conditions of an electrospray quadrupole time-of-flight mass spectrometers. The tandem mass spectrometry experiments were performed after the separation of the compounds with a reversed-phase high performance liquid chromatography method. We found that both, phosphorylated and nonphosphorylated lipid A molecules can be readily ionized in the positive-ion mode by adduct formation with triethylamine added to the eluent...
November 16, 2017: Journal of Mass Spectrometry: JMS
https://www.readbyqxmd.com/read/29144022/collagen-a-review-on-its-sources-and-potential-cosmetic-applications
#17
REVIEW
María Isabela Avila Rodríguez, Laura G Rodríguez Barroso, Mirna Lorena Sánchez
Collagen is a fibrillar protein that conforms the conjunctive and connective tissues in the human body, essentially skin, joints, and bones. This molecule is one of the most abundant in many of the living organisms due to its connective role in biological structures. Due to its abundance, strength and its directly proportional relation with skin aging, collagen has gained great interest in the cosmetic industry. It has been established that the collagen fibers are damaged with the pass of time, losing thickness and strength which has been strongly related with skin aging phenomena [Colágeno para todo...
November 16, 2017: Journal of Cosmetic Dermatology
https://www.readbyqxmd.com/read/29143694/cryo-scanning-electron-microscopy-sem-and-scanning-transmission-electron-microscopy-stem-in-sem-for-bio-and-organo-mineral-interface-characterization-in-the-environment
#18
Guillaume Wille, Jennifer Hellal, Patrick Ollivier, Annie Richard, Agnes Burel, Louis Jolly, Marc Crampon, Caroline Michel
Understanding biofilm interactions with surrounding substratum and pollutants/particles can benefit from the application of existing microscopy tools. Using the example of biofilm interactions with zero-valent iron nanoparticles (nZVI), this study aims to apply various approaches in biofilm preparation and labeling for fluorescent or electron microscopy and energy dispersive X-ray spectrometry (EDS) microanalysis for accurate observations. According to the targeted microscopy method, biofilms were sampled as flocs or attached biofilm, submitted to labeling using 4',6-diamidino-2-phenylindol, lectins PNA and ConA coupled to fluorescent dye or gold nanoparticles, and prepared for observation (fixation, cross-section, freezing, ultramicrotomy)...
November 16, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/29142298/shaping-bacterial-population-behavior-through-computer-interfaced-control-of-individual-cells
#19
Remy Chait, Jakob Ruess, Tobias Bergmiller, Gašper Tkačik, Călin C Guet
Bacteria in groups vary individually, and interact with other bacteria and the environment to produce population-level patterns of gene expression. Investigating such behavior in detail requires measuring and controlling populations at the single-cell level alongside precisely specified interactions and environmental characteristics. Here we present an automated, programmable platform that combines image-based gene expression and growth measurements with on-line optogenetic expression control for hundreds of individual Escherichia coli cells over days, in a dynamically adjustable environment...
November 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/29142288/identification-of-small-rnas-abundant-in-burkholderia-cenocepacia-biofilms-reveal-putative-regulators-with-a-potential-role-in-carbon-and-iron-metabolism
#20
Andrea Sass, Sanne Kiekens, Tom Coenye
Small RNAs play a regulatory role in many central metabolic processes of bacteria, as well as in developmental processes such as biofilm formation. Small RNAs of Burkholderia cenocepacia, an opportunistic pathogenic beta-proteobacterium, are to date not well characterised. To address that, we performed genome-wide transcriptome structure analysis of biofilm grown B. cenocepacia J2315. 41 unannotated short transcripts were identified in intergenic regions of the B. cenocepacia genome. 15 of these short transcripts, highly abundant in biofilms, widely conserved in Burkholderia sp...
November 15, 2017: Scientific Reports
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