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https://www.readbyqxmd.com/read/28323617/cryoem-structures-of-membrane-pore-and-prepore-complex-reveal-cytolytic-mechanism-of-pneumolysin
#1
Katharina van Pee, Alexander Neuhaus, Edoardo D'Imprima, Deryck J Mills, Werner Kühlbrandt, Özkan Yildiz
Many pathogenic bacteria produce pore-forming toxins to attack and kill human cells. We have determined the 4.5 Å structure of the ~2.2 MDa pore complex of pneumolysin, the main virulence factor of Streptococcus pneumoniae, by cryoEM. The pneumolysin pore is a 400 Å ring of 42 membrane-inserted monomers. Domain D3 of the soluble toxin refolds into two ~85 Å β-hairpins that traverse the lipid bilayer and assemble into a 168-strand β-barrel. The pore complex is stabilized by salt bridges between β-hairpins of adjacent subunits and an internal α-barrel...
March 21, 2017: ELife
https://www.readbyqxmd.com/read/28319867/phototherapeutic-spectrum-expansion-through-synergistic-effect-of-mesoporous-silica-trio-nanohybrids-against-antibiotic-resistant-gram-negative-bacterium
#2
Yaswanth Kuthati, Ranjith Kumar Kankala, Prabhakar Busa, Shi-Xiang Lin, Jin-Pei Deng, Chung-Yuan Mou, Chia-Hung Lee
The extensive impact of antibiotic resistance has led to the exploration of new anti-bacterial modalities. We designed copper impregnated mesoporous silica nanoparticles (Cu-MSN) with immobilizing silver nanoparticles (SNPs) to apply photodynamic inactivation (PDI) of antibiotic-resistant E. coli. SNPs were decorated over the Cu-MSN surfaces by coordination of silver ions on diamine-functionalized Cu-MSN and further reduced to silver nanoparticles with formalin. We demonstrate that silver is capable of sensitizing the gram-negative bacteria E...
March 7, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28319712/toxic-compounds-biodegradation-and-toxicity-of-high-strength-wastewater-treated-under-elevated-nitrogen-concentration-in-the-activated-sludge-and-membrane-bioreactor-systems
#3
Jarungwit Boonnorat, Nimaradee Boonapatcharoen, Pradthana Prachanurak, Ryo Honda, Supaporn Phanwilai
This research has assessed the removal efficiencies of toxic compounds in the high strength wastewater (the leachate and agriculture wastewater mixture) using the activated sludge (AS) and membrane bioreactor (MBR) technologies under two carbon to nitrogen (C/N) ratios (C/N 14 and 6) and two toxic compounds concentrations (8-396μg/L and 1000μg/L). In addition, the toxicity evaluations of the AS and MBR effluents to the aquatic environment were undertaken at five effluent dilution ratios (10, 20, 30, 50 and 70% v/v)...
March 16, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28319176/insight-into-the-mechanism-of-action-of-temporin-sha-a-new-broad-spectrum-antiparasitic-and-antibacterial-agent
#4
Zahid Raja, Sonia André, Feten Abbassi, Vincent Humblot, Olivier Lequin, Tahar Bouceba, Isabelle Correia, Sandra Casale, Thierry Foulon, Denis Sereno, Bruno Oury, Ali Ladram
Antimicrobial peptides (AMPs) are promising drugs to kill resistant pathogens. In contrast to bacteria, protozoan parasites, such as Leishmania, were little studied. Therefore, the antiparasitic mechanism of AMPs is still unclear. In this study, we sought to get further insight into this mechanism by focusing our attention on temporin-SHa (SHa), a small broad-spectrum AMP previously shown to be active against Leishmania infantum. To improve activity, we designed analogs of SHa and compared the antibacterial and antiparasitic mechanisms...
2017: PloS One
https://www.readbyqxmd.com/read/28319163/hopanoid-free-methylobacterium-extorquens-dm4-overproduces-carotenoids-and-has-widespread-growth-impairment
#5
Alexander S Bradley, Paige K Swanson, Emilie E L Muller, Françoise Bringel, Sean M Caroll, Ann Pearson, Stéphane Vuilleumier, Christopher J Marx
Hopanoids are sterol-like membrane lipids widely used as geochemical proxies for bacteria. Currently, the physiological role of hopanoids is not well understood, and this represents one of the major limitations in interpreting the significance of their presence in ancient or contemporary sediments. Previous analyses of mutants lacking hopanoids in a range of bacteria have revealed a range of phenotypes under normal growth conditions, but with most having at least an increased sensitivity to toxins and osmotic stress...
2017: PloS One
https://www.readbyqxmd.com/read/28317932/bacterial-secretion-system-skews-the-fate-of-legionella-containing-vacuoles-towards-lc3-associated-phagocytosis
#6
Andree Hubber, Tomoko Kubori, Cevayir Coban, Takeshi Matsuzawa, Michinaga Ogawa, Tsuyoshi Kawabata, Tamotsu Yoshimori, Hiroki Nagai
The evolutionarily conserved processes of endosome-lysosome maturation and macroautophagy are established mechanisms that limit survival of intracellular bacteria. Similarly, another emerging mechanism is LC3-associated phagocytosis (LAP). Here we report that an intracellular vacuolar pathogen, Legionella dumoffii, is specifically targeted by LAP over classical endocytic maturation and macroautophagy pathways. Upon infection, the majority of L. dumoffii resides in ER-like vacuoles and replicate within this niche, which involves inhibition of classical endosomal maturation...
March 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28317443/deterioration-of-the-anammox-process-at-decreasing-temperatures-and-long-srts
#7
Maaike Hoekstra, Florence A de Weerd, Robbert Kleerebezem, Mark C M van Loosdrecht
The implementation of autotrophic nitrogen removal in the mainstream of a municipal wastewater treatment plant is currently pursued. Among the crucial unknown factors are the kinetic properties of anaerobic ammonium oxidising (anammox) bacteria at low temperatures, as typically encountered for sewage in winter. In this study we investigated the adaptation of a fast growing anammox culture to a lower temperature. In a membrane bioreactor a highly enriched anammox community was obtained at 30, 25 and 20°C. The culture grew as free cells and small flocs (50 -150µm)...
March 19, 2017: Environmental Technology
https://www.readbyqxmd.com/read/28315603/dynamic-membrane-assisted-fermentation-of-food-wastes-for-enhancing-lactic-acid-production
#8
Jialing Tang, Xiaochang C Wang, Yisong Hu, Huu Hao Ngo, Yuyou Li
A dynamic membrane (DM) module was inserted into a fermentation reactor to separate soluble products from the fermented mixture to increase lactic acid (LA) production from food wastes under acidogenic conditions (uncontrolled pH, pH 4 and 5). With a high total suspended solid content (20-40g/L) in the fermenter, a stable DM could be maintained through regular backwashing. By effectively intercepting suspended solids and lactic acid bacteria (LAB), the fermenter was able to increase microbial activity and largely promote LA yield...
March 7, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28314230/toxicity-of-diatom-polyunsaturated-aldehydes-to-marine-bacterial-isolates-reveals-their-mode-of-action
#9
Milva Pepi, Hermann J Heipieper, Cecilia Balestra, Marco Borra, Elio Biffali, Raffaella Casotti
Diatoms produce and release polyunsaturated aldehydes (PUAs) during senescence in culture and at the end of blooms in nature and these compounds play different ecological roles, as infochemicals, allelochemicals and pheromones In order to elucidate the toxic effects of PUAs, we isolated six bacterial strains from the Mediterranean Sea during a diatom bloom and tested their tolerance to PUA in terms of growth and cell membrane properties. Based upon 16S rRNA sequencing, these bacteria were assigned to the genera Pseudomonas, Sufflavibacter, Halomonas, Vibrio, Idiomarina, and Labrenzia...
March 9, 2017: Chemosphere
https://www.readbyqxmd.com/read/28303956/inhibitory-role-of-acyl-homoserine-lactones-in-hemolytic-activity-and-viability-of-streptococcus-pyogenes-m6-s165
#10
Sunil D Saroj, Linda Holmer, Júlia M Berengueras, Ann-Beth Jonsson
Streptococcus pyogenes an adapted human pathogen asymptomatically colonizes the nasopharynx, among other polymicrobial communities. However, information on the events leading to the colonization and expression of virulence markers subject to interspecies and host-bacteria interactions are limited. The interference of acyl homoserine lactones (AHLs) with the hemolytic activity and viability of S. pyogenes M6 S165 was examined. AHLs, with fatty acid side chains ≥12 carbon atoms, inhibited hemolytic activity by downregulating the expression of the sag operon involved in the production of streptolysin S...
March 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28302399/elucidation-of-structural-and-functional-integration-of-a-novel-antimicrobial-peptide-from-antheraea-mylitta
#11
Suhrid R Dutta, Samiran S Gauri, Twisa Ghosh, Suman K Halder, Pradeep K DasMohapatra, Keshab C Mondal, Ananta K Ghosh
We report here the amino acid sequence of an antimicrobial peptide of Antheraea mylitta (peptide fraction II) effectively killed urinary tract associated MDR E. coli (Dutta et al., 2016), as Gly-Gly-Gly-Gly-Gly-Gly-His-Leu-Val-Ala. The physicochemical and biological properties of this peptide were evaluated by computational analysis and its isoelectric point, grand average of hydropathicity and Boman index values were found to be 6.74, 0.42 and -1.17kcal/mol, respectively. One valid model of peptide fraction II was constructed, that contains two antiparallel β sheets with a hairpin and appeared as 'U' shaped structure...
March 3, 2017: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28301286/chlorine-dioxide-oxidation-of-escherichia-coli-in-water-a-study-of-the-disinfection-kinetics-and-mechanism
#12
Isaac Ofori, Suresh Maddila, Johnson Lin, Sreekantha B Jonnalagadda
This study investigated the kinetics and mechanism of chlorine dioxide (ClO2) inactivation of a Gram-negative bacteria Escherichia coli (ATCC 35218) in oxidant demand free (ODF) water in detail as a function of disinfectant concentration (0.5-5.0 mg/L), water pH (6.5-8.5), temperature variations (4-37°C) and bacterial density (10(5)-10(7) cfu/mL). The effects of ClO2 on bacterial cell morphology, outer membrane permeability, cytoplasmic membrane disruption and intracellular enzymatic activity were also studied to elucidate the mechanism of action on the cells...
March 16, 2017: Journal of Environmental Science and Health. Part A, Toxic/hazardous Substances & Environmental Engineering
https://www.readbyqxmd.com/read/28300180/systems-level-understanding-of-ethanol-induced-stresses-and-adaptation-in-e-coli
#13
Huansheng Cao, Du Wei, Yuedong Yang, Yu Shang, Gaoyang Li, Yaoqi Zhou, Qin Ma, Ying Xu
Understanding ethanol-induced stresses and responses in biofuel-producing bacteria at systems level has significant implications in engineering more efficient biofuel producers. We present a computational study of transcriptomic and genomic data of both ethanol-stressed and ethanol-adapted E. coli cells with computationally predicated ethanol-binding proteins and experimentally identified ethanol tolerance genes. Our analysis suggests: (1) ethanol damages cell wall and membrane integrity, causing increased stresses, particularly reactive oxygen species, which damages DNA and reduces the O2 level; (2) decreased cross-membrane proton gradient from membrane damage, coupled with hypoxia, leads to reduced ATP production by aerobic respiration, driving cells to rely more on fatty acid oxidation, anaerobic respiration and fermentation for ATP production; (3) the reduced ATP generation results in substantially decreased synthesis of macromolecules; (4) ethanol can directly bind 213 proteins including transcription factors, altering their functions; (5) all these changes together induce multiple stress responses, reduced biosynthesis, cell viability and growth; and (6) ethanol-adapted E...
March 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28300142/late-assembly-of-the-vibrio-cholerae-cell-division-machinery-postpones-septation-to-the-last-10-of-the-cell-cycle
#14
Elisa Galli, Evelyne Paly, François-Xavier Barre
Bacterial cell division is a highly regulated process, which involves the formation of a complex apparatus, the divisome, by over a dozen proteins. In the few model bacteria in which the division process was detailed, divisome assembly occurs in two distinct steps: a few proteins, including the FtsZ tubulin-like protein, form a membrane associated contractile ring, the Z-ring, at ~30% of the cell cycle. The Z-ring serves as a scaffold for the recruitment of a second series of proteins, including integral membrane and periplasmic cell wall remodelling enzymes, at ~50% of the cell cycle...
March 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28299865/novel-short-antimicrobial-peptide-isolated-from-xenopus-laevis-skin
#15
Yu Zhang, Songcai Liu, Siming Li, Yunyun Cheng, Linyan Nie, Gang Wang, Chen Lv, Wenzhen Wei, Cheng Cheng, Feng Hou, Linlin Hao
A rich source of bioactive peptides, including a large number of antimicrobial peptides, has been found in amphibian skin. In this study, a novel short antimicrobial peptide was purified from Xenopus laevis skin and characterised through reversed-phase high-performance liquid chromatography, Edman degradation and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. The peptide was composed of six amino acids with a sequence of DEDLDE and thus named X. laevis antibacterial peptide-P2 (XLAsp-P2)...
March 16, 2017: Journal of Peptide Science: An Official Publication of the European Peptide Society
https://www.readbyqxmd.com/read/28299860/poly-3-hydroxybutyrate-fuels-the-tricarboxylic-acid-cycle-and-de-novo-lipid-biosynthesis-during-bacillus-anthracis-sporulation
#16
Marat R Sadykov, Jong-Sam Ahn, Todd J Widhelm, Valerie M Eckrich, Jennifer L Endres, Adam Driks, Gregory E Rutkowski, Kevin L Wingerd, Kenneth W Bayles
Numerous bacteria accumulate poly(3-hydroxybutyrate) (PHB) as an intracellular reservoir of carbon and energy in response to imbalanced nutritional conditions. In Bacillus spp., where PHB biosynthesis precedes the formation of the dormant cell type called the spore (sporulation), the direct link between PHB accumulation and efficiency of sporulation was observed in multiple studies. Although the idea of PHB as an intracellular carbon and energy source fueling sporulation was proposed several decades ago, the mechanisms underlying PHB contribution to sporulation have not been defined...
March 16, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28299840/antimicrobial-activity-and-stability-of-protonectin-with-d-amino-acid-substitutions
#17
Shuai Qiu, Ranran Zhu, Yanyan Zhao, Xiaoping An, Fengjing Jia, Jinxiu Peng, Zelin Ma, Yuanyuan Zhu, Jiayi Wang, Jinhuan Su, Qingjun Wang, Hailin Wang, Yuan Li, Kairong Wang, Wenjin Yan, Rui Wang
The misuse and overuse of antibiotics result in the emergence of resistant bacteria and fungi, which make an urgent need of the new antimicrobial agents. Nowadays, antimicrobial peptides have attracted great attention of researchers. However, the low physiological stability in biological system limits the application of naturally occurring antimicrobial peptides as novel therapeutics. In the present study, we synthesized derivatives of protonectin by substituting all the amino acid residues or the cationic lysine residue with the corresponding D-amino acids...
March 16, 2017: Journal of Peptide Science: An Official Publication of the European Peptide Society
https://www.readbyqxmd.com/read/28299749/osmotic-stress-in-colony-and-planktonic-cells-of-pseudomonas-putida-mt-2-revealed-significant-differences-in-adaptive-response-mechanisms
#18
Nancy Hachicho, Astrid Birnbaum, Hermann J Heipieper
Planktonic cells and those grown on surfaces (or as colony biofilm) are known to show significant differences regarding growth behavior, cell physiology, gene expression and stress tolerance. In order to compare stress behavior of different growth forms, shake cultures for planktonic growth and agar plate cultivation for colony growth, were carried out with the well investigated model organism, Pseudomonas putida mt-2. Cells were exposed to sodium chloride to cause osmotic stress as one main environmental stressor bacteria have to cope with when growing in soil...
December 2017: AMB Express
https://www.readbyqxmd.com/read/28299286/the-rickettsia-conorii-adr1-interacts-with-the-c-terminus-of-human-vitronectin-in-a-salt-sensitive-manner
#19
Abigail I Fish, Sean P Riley, Birendra Singh, Kristian Riesbeck, Juan J Martinez
Spotted fever group (SFG) Rickettsia species are inoculated into the mammalian bloodstream by hematophagous arthropods. Once in the bloodstream and during dissemination, the survival of these pathogens is dependent upon the ability of these bacteria to evade serum-borne host defenses until a proper cellular host is reached. Rickettsia conorii expresses an outer membrane protein, Adr1, which binds the complement inhibitory protein vitronectin to promote resistance to the anti-bacterial effects of the terminal complement complex...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28296562/immunomodulatory-yersinia-outer-proteins-yops-useful-tools-for-bacteria-and-humans-alike
#20
Benjamin Grabowski, M Alexander Schmidt, Christian Rüter
Human-pathogenic Yersinia produce plasmid-encoded Yersinia outer proteins (Yops), which are necessary to down-regulate anti-bacterial responses that constrict bacterial survival in the host. These Yops are effectively translocated directly from the bacterial into the target cell cytosol by the type III secretion system (T3SS). Cell-penetrating peptides (CPPs) in contrast are characterized by their ability to autonomously cross cell membranes and to transport cargo - independent of additional translocation systems...
March 15, 2017: Virulence
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