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https://www.readbyqxmd.com/read/28730969/the-battle-for-iron-between-humans-and-microbes
#1
Peggy L Carver
Iron is an essential micronutrient for bacteria, fungi, and humans; as such, each has evolved specialized iron uptake systems to acquire iron from the extracellular environment and a complex 'tug of war' has evolved between human hosts and pathogenic microorganisms in the battle for this vital nutrient. In humans, sequestration (hiding) of iron from invading pathogens is often successful; however, many pathogens have evolved mechanisms to circumvent this approach. Clinically, controversy continues whether iron overload or administration of iron results in an increased risk of infection...
July 20, 2017: Current Medicinal Chemistry
https://www.readbyqxmd.com/read/28729854/microbiome-of-trichodesmium-colonies-from-the-north-pacific-subtropical-gyre
#2
Mary R Gradoville, Byron C Crump, Ricardo M Letelier, Matthew J Church, Angelicque E White
Filamentous diazotrophic Cyanobacteria of the genus Trichodesmium, often found in colonial form, provide an important source of new nitrogen to tropical and subtropical marine ecosystems. Colonies are composed of several clades of Trichodesmium in association with a diverse community of bacterial and eukaryotic epibionts. We used high-throughput 16S rRNA and nifH gene sequencing, carbon (C) and dinitrogen (N2) fixation assays, and metagenomics to describe the diversity and functional potential of the microbiome associated with Trichodesmium colonies collected from the North Pacific Subtropical Gyre (NPSG)...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28717590/construction-of-a-fur-null-mutant-and-rna-sequencing-provide-deeper-global-understanding-of-the-aliivibrio-salmonicida-fur-regulon
#3
Sunniva Katharina Thode, Cecilie Bækkedal, Jenny Johansson Söderberg, Erik Hjerde, Hilde Hansen, Peik Haugen
BACKGROUND: The ferric uptake regulator (Fur) is a transcription factor and the main regulator of iron acquisition in prokaryotes. When bound to ferric iron, Fur recognizes its DNA binding site and generally executes its function by repressing transcription of its target genes. Due to its importance in virulence, the Fur regulon is well studied for several model bacteria. In our previous work, we used computational predictions and microarray to gain insights into Fur-regulation in Aliivibrio salmonicida, and have identified a number of genes and operons that appear to be under direct control of Fur...
2017: PeerJ
https://www.readbyqxmd.com/read/28717421/isolation-of-membrane-vesicles-from-prokaryotes-a-technical-and-biological-comparison-reveals-heterogeneity
#4
Priscila Dauros Singorenko, Vanessa Chang, Alana Whitcombe, Denis Simonov, Jiwon Hong, Anthony Phillips, Simon Swift, Cherie Blenkiron
Prokaryotes release membrane vesicles (MVs) with direct roles in disease pathogenesis. MVs are heterogeneous when isolated from bacterial cultures so Density Gradient Centrifugation (DGC) is valuable for separation of MV subgroups from contaminating material. Here we report the technical variability and natural biological heterogeneity seen between DGC preparations of MVs for Mycobacterium smegmatis and Escherichia coli and compare these DGC data with size exclusion chromatography (SEC) columns. Crude preparations of MVs, isolated from cultures by ultrafiltration and ultracentrifugation were separated by DGC with fractions manually collected as guided by visible bands...
2017: Journal of Extracellular Vesicles
https://www.readbyqxmd.com/read/28715664/electron-transfer-mediators-accelerated-the-microbiologically-influence-corrosion-against-carbon-steel-by-nitrate-reducing-pseudomonas-aeruginosa-biofilm
#5
Ru Jia, Dongqing Yang, Dake Xu, Tingyue Gu
Electron transfer is a rate-limiting step in microbiologically influenced corrosion (MIC) caused by microbes that utilize extracellular electrons. Cross-cell wall electron transfer is necessary to transport the electrons released from extracellular iron oxidation into the cytoplasm of cells. Electron transfer mediators were found to accelerate the MIC caused by sulfate reducing bacteria. However, there is no publication in the literature showing the effect of electron transfer mediators on MIC caused by nitrate reducing bacteria (NRB)...
June 29, 2017: Bioelectrochemistry
https://www.readbyqxmd.com/read/28712636/human-exoproteome-in-acute-apical-abscesses
#6
Cristiane F Alfenas, Tiago A O Mendes, Humberto J O Ramos, Fernanda P Bruckner, Henrique S Antunes, Isabela N Rôças, José F Siqueira, José C Provenzano
INTRODUCTION: An acute apical abscess is a severe response of the host to massive invasion of the periapical tissues by bacteria from infected root canals. Although many studies have investigated the microbiota involved in the process, information on the host factors released during abscess formation is scarce. The purpose of this study was to describe the human exoproteome in samples from acute apical abscesses. METHODS: Fourteen pus samples were obtained by aspiration from patients with an acute apical abscess...
July 13, 2017: Journal of Endodontics
https://www.readbyqxmd.com/read/28710587/characterization-of-the-sulfur-formation-suf-genes-in-synechocystis-sp-pcc-6803-under-photoautotrophic-and-heterotrophic-growth-conditions
#7
Sha-Sha Zang, Hai-Bo Jiang, Wei-Yu Song, Min Chen, Bao-Sheng Qiu
The sulfur-formation ( suf ) genes play important roles in both photosynthesis and respiration of cyanobacteria, but the organism prioritizes Fe-S clusters for respiration at the expense of photosynthesis. Iron-sulfur (Fe-S) clusters are important to all living organisms, but their assembly mechanism is poorly understood in photosynthetic organisms. Unlike non-photosynthetic bacteria that rely on the iron-sulfur cluster system, Synechocystis sp. PCC 6803 uses the Sulfur-Formation (SUF) system as its major Fe-S cluster assembly pathway...
July 14, 2017: Planta
https://www.readbyqxmd.com/read/28710276/atp-binding-and-hydrolysis-disrupts-the-high-affinity-interaction-between-the-heme-abc-transporter-hmuuv-and-its-cognate-substrate-binding-protein
#8
Hiba Qasem Abdullah, Michal Perach, Nurit Livnat-Levanon, Oded Lewinson
Using the energy of ATP hydrolysis ABC transporters catalyze the trans-membrane transport of molecules. In bacteria they partner with a high affinity substrate binding protein (SBP) to import essential micronutrients. ATP binding by Type-I ABC transporters (importers of amino acids, sugars, peptides, small ions) stabilizes the interaction between the transporter and the SBP, thus allowing transfer of the substrate from the latter to the former. In Type-II ABC transporters (importers of trace elements, e.g., vitamin B12, heme, iron-siderophores) the role of ATP remains debatable...
July 14, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28708324/ferrichrome-has-found-its-match-biomimetic-analogs-with-diversified-activity-map-discrete-microbial-targets
#9
Jenny Besserglick, Evgenia Olshvang, Agnieszka Szebesczyk, Joseph Englander, Dana Levinson, Yitzhak Hadar, Elzbieta Gumienna-Kontecka, Abraham Shanzer
Siderophores provide an established platform for studying molecular recognition principles in biological systems. Herein we describe the preparation of ferrichrome biomimetic analogs varying in length and polarity of the amino acid chain separating between the tripodal scaffold and the pendent FeIII chelating hydroxamic acid groups. Spectroscopic and potentiometric titrations determined their iron affinity to be within the range of efficient chelators. Microbial growth promotion and iron uptake studies were conducted on E...
July 14, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28701557/the-physical-boundaries-of-public-goods-cooperation-between-surface-attached-bacterial-cells
#10
Michael Weigert, Rolf Kümmerli
Bacteria secrete a variety of compounds important for nutrient scavenging, competition mediation and infection establishment. While there is a general consensus that secreted compounds can be shared and therefore have social consequences for the bacterial collective, we know little about the physical limits of such bacterial social interactions. Here, we address this issue by studying the sharing of iron-scavenging siderophores between surface-attached microcolonies of the bacterium Pseudomonas aeruginosa Using single-cell fluorescence microscopy, we show that siderophores, secreted by producers, quickly reach non-producers within a range of 100 µm, and significantly boost their fitness...
July 12, 2017: Proceedings. Biological Sciences
https://www.readbyqxmd.com/read/28700833/diversity-and-arsenic-tolerance-potential-of-bacterial-communities-from-soil-and-sediments-along-a-gold-tailing-contamination-gradient
#11
Xiangyu Guan, Xu Yan, Youxun Li, Bo Jiang, Ximing Luo, Xiaoyuan Chi
Gold tailings often lead to the release of arsenic (As) contaminants into the surrounding environment. Microorganisms play an important role in the As cycle, whereas the effects of As on bacterial communities remain unclear. To reveal the effects of As on diversity and variation of bacterial communities and their As-tolerance potential, farmland soil and river sediment samples were collected according to distance from tailings in Dandong area of northeastern China. The bacterial communities were analyzed using high-throughput sequencing of 16S rRNA genes...
July 12, 2017: Canadian Journal of Microbiology
https://www.readbyqxmd.com/read/28695856/crystal-structure-of-yersinia-pestis-virulence-factor-yfea-reveals-two-polyspecific-metal-binding-sites
#12
Christopher D Radka, Lawrence J DeLucas, Landon S Wilson, Matthew B Lawrenz, Robert D Perry, Stephen G Aller
Gram-negative bacteria use siderophores, outer membrane receptors, inner membrane transporters and substrate-binding proteins (SBPs) to transport transition metals through the periplasm. The SBPs share a similar protein fold that has undergone significant structural evolution to communicate with a variety of differentially regulated transporters in the cell. In Yersinia pestis, the causative agent of plague, YfeA (YPO2439, y1897), an SBP, is important for full virulence during mammalian infection. To better understand the role of YfeA in infection, crystal structures were determined under several environmental conditions with respect to transition-metal levels...
July 1, 2017: Acta Crystallographica. Section D, Structural Biology
https://www.readbyqxmd.com/read/28691898/post-transcriptional-regulation-of-target-genes-by-the-srna-fnrs-in-neisseria-gonorrhoeae
#13
Pooja Tanwer, Susanne Bauer, Elisabeth Heinrichs, Gurudutta Panda, Daman Saluja, Thomas Rudel, Dagmar Beier
Small non-coding RNAs (sRNAs) are well-established post-transcriptional regulators of gene expression in bacteria that respond to a variety of environmental stimuli. They usually act by base-pairing with their target mRNAs, which is commonly facilitated by the RNA chaperone Hfq. In this study we initiated the analysis of the sRNA FnrS of Neisseria gonorrhoeae, which is induced under anaerobic conditions. We identified four putative FnrS target genes using bioinformatics approaches and validated these target genes using translational reporter gene fusions in both Escherichia coli and N...
July 10, 2017: Microbiology
https://www.readbyqxmd.com/read/28691023/iron-homeostasis-in-tissues-is-affected-during-persistent-chlamydia-pneumoniae-infection-in-mice
#14
Marie Edvinsson, Jonas Tallkvist, Christina Nyström-Rosander, Nils-Gunnar Ilbäck
Chlamydia pneumoniae (C. pneumoniae) may be a mediator in the pathogenesis of atherosclerosis. For its growth C. pneumoniae depends on iron (Fe), but how Fe changes in tissues during persistent infection or affects bacterial replication in tissues is unknown. C. pneumoniae-infected C57BL/6J mice were sacrificed on days 4, 8, 20, and 40. Mice had bacteria in the lungs and liver on all days. Inflammatory markers, chemokine Cxcl2 and interferon-gamma, were not affected in the liver on day 40. The copper (Cu)/zinc (Zn) ratio in serum, another marker of infection/inflammation, increased on day 4 and tended to increase again on day 40...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28690982/deferiprone-and-gallium-protoporphyrin-have-the-capacity-to-potentiate-the-activity-of-antibiotics-in-staphylococcus-aureus-small-colony-variants
#15
Katharina Richter, Nicky Thomas, Guimin Zhang, Clive A Prestidge, Tom Coenye, Peter-John Wormald, Sarah Vreugde
Small colony variants (SCVs) of bacteria like Staphylococcus aureus are characterized by a reduced colony size and are linked to increased antibiotic tolerance and resistance. Their altered expression of virulence factors, slow growing properties and their ability to form biofilms make the eradication of SCVs challenging. In the context of biofilm-related infectious diseases involving S. aureus SCVs, a therapy targeting bacterial iron metabolism was evaluated. The combination of the iron-chelator deferiprone (Def) and the heme-analog gallium-protoporphyrin (GaPP), in solution and incorporated in a surgical wound gel, was tested for activity against planktonic and sessile SCVs...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28690060/genetically-modified-lactococcus-lactis-producing-a-green-fluorescence-protein-bovine-lactoferrin-fusion-protein-suppresses-proinflammatory-cytokine-expression-in-lipopolysaccharide-stimulated-raw-264-7-cells
#16
S Shigemori, F Namai, Y Yamamoto, S Nigar, T Sato, T Ogita, T Shimosato
Lactoferrin (LF), an iron-binding glycoprotein distributed widely in the biological fluids of mammals, is believed to play an important role in host defenses against infection. Previous studies in animal models and humans demonstrated that combined administration of LF and probiotic lactic acid bacteria (LAB) can prevent sepsis. In this study, we genetically engineered a probiotic LAB strain, Lactococcus lactis, to produce recombinant bovine LF based on the green fluorescence protein (GFP)-fused expression system...
July 6, 2017: Journal of Dairy Science
https://www.readbyqxmd.com/read/28689117/development-of-non-pyrogenic-magnetosome-minerals-coated-with-poly-l-lysine-leading-to-full-disappearance-of-intracranial-u87-luc-glioblastoma-in-100-of-treated-mice-using-magnetic-hyperthermia
#17
Edouard Alphandéry, Ahmed Idbaih, Clovis Adam, Jean-Yves Delattre, Charlotte Schmitt, François Guyot, Imène Chebbi
Magnetic hyperthermia was reported to increase the survival of patients with recurrent glioblastoma by 7 months. This promising result may potentially be further improved by using iron oxide nanoparticles, called magnetosomes, which are synthesized by magnetotactic bacteria, extracted from these bacteria, purified to remove most endotoxins and organic material, and then coated with poly-l-lysine to yield a stable and non-pyrogenic nanoparticle suspension. Due to their ferrimagnetic behavior, high crystallinity and chain arrangement, these magnetosomes coated with poly-l-lysine (M-PLL) are characterized by a higher heating power than their chemically synthesized counterparts currently used in clinical trials...
June 21, 2017: Biomaterials
https://www.readbyqxmd.com/read/28686931/sulfate-enhances-the-dissimilatory-arsenate-respiring-prokaryotes-mediated-mobilization-reduction-and-release-of-insoluble-arsenic-and-iron-from-the-arsenic-rich-sediments-into-groundwater
#18
Jianing Wang, Xian-Chun Zeng, Xianbin Zhu, Xiaoming Chen, Xin Zeng, Yao Mu, Ye Yang, Yanxin Wang
Dissimilatory arsenate-respiring prokaryotes (DARPs) play key roles in the mobilization and release of arsenic from mineral phase into groundwater; however, little is known about how environmental factors influence these processes. This study aimed to explore the effects of sulfate on the dissolution and release of insoluble arsenic. We collected high-arsenic sediment samples from different depths in Jianghan Plain. Microcosm assays indicated that the microbial communities from the samples significantly catalyzed the dissolution, reduction and release of arsenic and iron from the sediments...
June 23, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28684420/structural-and-biochemical-analyses-indicate-that-a-bacterial-persulfide-dioxygenase-rhodanese-fusion-protein-functions-in-sulfur-assimilation
#19
Nicole Motl, Meredith A Skiba, Omer Kabil, Janet L Smith, Ruma Banerjee
Hydrogen sulfide (H2S) is a signaling molecule that is toxic at elevated concentrations. In eukaryotes, it is cleared via a mitochondrial sulfide oxidation pathway, which comprises sulfide quinone oxidoreductase, persulfide dioxygenase (PDO), rhodanese, and sulfite oxidase and converts H2S to thiosulfate and sulfate. Natural fusions between the non-heme iron containing PDO and rhodanese, a thiol sulfurtransferase, exist in some bacteria. However, little is known about the role of the PDO-rhodanese fusion (PRF) proteins in sulfur metabolism...
July 6, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28680861/nramp1-and-nrampb-contribute-to-resistance-against-francisella-in-dictyostelium
#20
Yannick Brenz, Denise Ohnezeit, Hanne C Winther-Larsen, Monica Hagedorn
The Francisella genus comprises highly pathogenic bacteria that can cause fatal disease in their vertebrate and invertebrate hosts including humans. In general, Francisella growth depends on iron availability, hence, iron homeostasis must be tightly regulated during Francisella infection. We used the system of the professional phagocyte Dictyostelium and the fish pathogen F. noatunensis subsp. noatunensis (F.n.n.) to investigate the role of the host cell iron transporters Nramp (natural resistance associated macrophage proteins) during Francisella infection...
2017: Frontiers in Cellular and Infection Microbiology
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