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https://www.readbyqxmd.com/read/28647534/molecular-cell-biology-of-complement-membrane-attack
#1
REVIEW
B Paul Morgan, Courtney Boyd, Doryen Bubeck
The membrane attack complex (MAC) is the pore-forming toxin of the complement system, a relatively early evolutionary acquisition that confers upon complement the capacity to directly kill pathogens. The MAC is more than just a bactericidal missile, having the capacity when formed on self-cells to initiate a host of cell activation events that can have profound consequences for tissue homeostasis in the face of infection or injury. Although the capacity of complement to directly kill pathogens has been recognised for over a century, and the pore-forming killing mechanism for at least 50 years, there remains considerable uncertainty regarding precisely how MAC mediates its killing and cell activation activities...
June 21, 2017: Seminars in Cell & Developmental Biology
https://www.readbyqxmd.com/read/28647277/risk-factors-for-nosocomial-infections-in-patients-receiving-extracorporeal-membrane-oxygenation-supportive-therapy
#2
Geqin Sun, Binfei Li, Haili Lan, Juan Wang, Lanfei Lu, Xueqin Feng, Xihua Luo, Haizhong Yan, Yuejing Mu
BACKGROUND AND OBJECTIVE: The aim of this study was to analyze risk factors for nosocomial infection (NI) in patients receiving extracorporeal membrane oxygenation (ECMO) support. PATIENTS AND METHODS: Clinical NI data were collected from patients who received ECMO support therapy, and analyzed retrospectively. RESULTS: Among 75 ECMO patients, 20 were found to have developed NI (infection rate 26.7%); a total of 58 pathogens were isolated, including 43 strains of gram-negative bacteria (74...
June 21, 2017: Medicina Clínica
https://www.readbyqxmd.com/read/28646448/purification-of-the-exopolysaccharide-produced-by-alteromonas-infernus-identification-of-endotoxins-and-effective-process-to-remove-them
#3
Alicia Grivaud-Le Du, Agata Zykwinska, Corinne Sinquin, Jacqueline Ratiskol, Pierre Weiss, Claire Vinatier, Jérôme Guicheux, Christine Delbarre-Ladrat, Sylvia Colliec-Jouault
Alteromonas infernus bacterium isolated from deep-sea hydrothermal vents can produce by fermentation a high molecular weight exopolysaccharide (EPS) called GY785. This EPS described as a new source of glycosaminoglycan-like molecule presents a great potential for pharmaceutical and biotechnological applications. However, this unusual EPS is secreted by a Gram-negative bacterium and can be therefore contaminated by endotoxins, in particular the lipopolysaccharides (LPS). Biochemical and chemical analyses of the LPS extracted from A...
June 23, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28646447/microbial-transformations-of-selenite-by-methane-oxidizing-bacteria
#4
Abdurrahman S Eswayah, Thomas J Smith, Andreas C Scheinost, Nicole Hondow, Philip H E Gardiner
Methane-oxidizing bacteria are well known for their role in the global methane cycle and their potential for microbial transformation of wide range of hydrocarbon and chlorinated hydrocarbon pollution. Recently, it has also emerged that methane-oxidizing bacteria interact with inorganic pollutants in the environment. Here, we report what we believe to be the first study of the interaction of pure strains of methane-oxidizing bacteria with selenite. Results indicate that the commonly used laboratory model strains of methane-oxidizing bacteria, Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b, are both able to reduce the toxic selenite (SeO3(2-)) but not selenate (SeO4(2-)) to red spherical nanoparticulate elemental selenium (Se(0)), which was characterized via energy-dispersive X-ray spectroscopy (EDXS), X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS)...
June 23, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28646115/genome-analysis-of-endomicrobium-proavitum-suggests-loss-and-gain-of-relevant-functions-during-the-evolution-of-intracellular-symbionts
#5
Hao Zheng, Carsten Dietrich, Andreas Brune
Bacterial endosymbionts of eukaryotes show progressive genome erosion, but detailed investigations of the evolutionary processes involved in the transition to an intracellular lifestyle are generally hampered by the lack of extant free-living lineages. Here, we characterize the genome of the recently isolated, free-living Endomicrobium proavitum, the second member of the Elusimicrobia phylum brought into pure culture, and compare it to the closely related "Candidatus Endomicrobium trichonymphae" strain Rs-D17, a previously described but uncultured endosymbiont of termite gut flagellates...
June 23, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28646114/staphylococcus-aureus-strain-newman-photoinactivation-and-cellular-response-to-sunlight-exposure
#6
Jill S McClary, Lauren M Sassoubre, Alexandria B Boehm
Sunlight influences microbial water quality of surface waters. Previous studies have investigated photoinactivation mechanisms and cellular photostress responses of fecal indicator bacteria (FIB), including Escherichia coli and enterococci, but further work is needed to characterize photostress responses of bacterial pathogens. Here we investigate the photoinactivation of Staphylococcus aureus (strain Newman), a pigmented, waterborne pathogen of emerging concern. We measured photodecay using standard culture-based assays and cellular membrane integrity; and investigated photostress response by measuring the relative number of mRNA transcripts of select oxidative stress, DNA repair, and metabolism genes...
June 23, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28644410/enhanced-antibacterial-activity-of-ent-labdane-derivatives-of-salvic-acid-7%C3%AE-hydroxy-8-17-ent-labden-15-oic-acid-effect-of-lipophilicity-and-the-hydrogen-bonding-role-in-bacterial-membrane-interaction
#7
Javier Echeverría, Alejandro Urzúa, Loreto Sanhueza, Marcela Wilkens
In the present study, the antibacterial activity of several ent-labdane derivatives of salvic acid (7α-hydroxy-8(17)-ent-labden-15-oic acid) was evaluated in vitro against the Gram-negative bacterium Escherichia coli and the Gram-positive bacteria Staphylococcus aureus and Bacillus cereus. For all of the compounds, the antibacterial activity was expressed as the minimum inhibitory concentration (MIC) in liquid media and minimum inhibitory amount (MIA) in solid media. Structure activity relationships (SAR) were employed to correlate the effect of the calculated lipophilicity parameters (logPow) on the inhibitory activity...
June 23, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28642439/assembly-principles-and-structure-of-a-6-5-mda-bacterial-microcompartment-shell
#8
Markus Sutter, Basil Greber, Clement Aussignargues, Cheryl A Kerfeld
Many bacteria contain primitive organelles composed entirely of protein. These bacterial microcompartments share a common architecture of an enzymatic core encapsulated in a selectively permeable protein shell; prominent examples include the carboxysome for CO2 fixation and catabolic microcompartments found in many pathogenic microbes. The shell sequesters enzymatic reactions from the cytosol, analogous to the lipid-based membrane of eukaryotic organelles. Despite available structural information for single building blocks, the principles of shell assembly have remained elusive...
June 23, 2017: Science
https://www.readbyqxmd.com/read/28642371/electrostatic-interactions-between-the-ctx-phage-minor-coat-protein-and-the-bacterial-host-receptor-tola-drives-the-pathogenic-conversion-of-vibrio-cholerae
#9
Laetitia Houot, Romain Navarro, Matthieu Nouailler, Denis Duché, Françoise Guerlesquin, Roland Lloubes
Vibrio cholerae is a natural inhabitant of aquatic environments and converts to a pathogen upon infection by a filamentous phage, CTXφ, that transmits the cholera toxin encoding genes. This toxigenic conversion of V. cholerae has evident implication in both genome plasticity and epidemic risk, but the early stages of the infection have not been thoroughly studied. CTXφ transit across the bacterial periplasm requires binding between the minor coat protein named pIII and a bacterial inner-membrane receptor, TolA, which is part of the conserved Tol-Pal molecular motor...
June 22, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28640578/the-insect-analogue-to-the-lotus-leaf-a-planthopper-wing-membrane-incorporating-a-low-adhesion-non-wetting-superhydrophobic-bactericidal-and-biocompatible-surface
#10
Gregory Shaun Watson, David W Green, Bronwen W Cribb, Christopher Leslie Brown, Christopher Merritt, Mark James Tobin, Jitraporn Vongsvivut, Ming-Xia Sun, Alping Liang, Jolanta Anna Watson
Nature has produced many intriguing and spectacular surfaces at the micro and nanoscales. These small surface decorations act for a singular or, in most cases, a range of functions. The minute landscape found on the lotus leaf is one such example, displaying anti-wetting behaviour and low adhesion with foreign particulate matter. Indeed the lotus leaf has often been considered the 'benchmark' for such properties. One could expect that there are animal counterparts of this self-drying and self-cleaning surface system...
June 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28639360/the-mechanism-of-coupling-between-oxido-reduction-and-proton-translocation-in-respiratory-chain-enzymes
#11
Sergio Papa, Giuseppe Capitanio, Francesco Papa
The respiratory chain of mitochondria and bacteria is made up of a set of membrane-associated enzyme complexes which catalyse sequential, stepwise transfer of reducing equivalents from substrates to oxygen and convert redox energy into a transmembrane protonmotive force (PMF) by proton translocation from a negative (N) to a positive (P) aqueous phase separated by the coupling membrane. There are three basic mechanisms by which a membrane-associated redox enzyme can generate a PMF. These are membrane anisotropic arrangement of the primary redox catalysis with: (i) vectorial electron transfer by redox metal centres from the P to the N side of the membrane; (ii) hydrogen transfer by movement of quinones across the membrane, from a reduction site at the N side to an oxidation site at the P side; (iii) a different type of mechanism based on co-operative allosteric linkage between electron transfer at the metal redox centres and transmembrane electrogenic proton translocation by apoproteins...
June 21, 2017: Biological Reviews of the Cambridge Philosophical Society
https://www.readbyqxmd.com/read/28638806/in-vitro-increased-respiratory-activity-of-selected-oral-bacteria-may-explain-competitive-and-collaborative-interactions-in-the-oral-microbiome
#12
Emma Hernandez-Sanabria, Vera Slomka, Esteban R Herrero, Frederiek-Maarten Kerckhof, Lynette Zaidel, Wim Teughels, Nico Boon
Understanding the driving forces behind the shifts in the ecological balance of the oral microbiota will become essential for the future management and treatment of periodontitis. As the use of competitive approaches for modulating bacterial outgrowth is unexplored in the oral ecosystem, our study aimed to investigate both the associations among groups of functional compounds and the impact of individual substrates on selected members of the oral microbiome. We employed the Phenotype Microarray high-throughput technology to analyse the microbial cellular phenotypes of 15 oral bacteria...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28638787/bioadhesive-bacterial-microswimmers-for-targeted-drug-delivery-in-the-urinary-and-gastrointestinal-tracts
#13
Babak Mostaghaci, Oncay Yasa, Jiang Zhuang, Metin Sitti
Bacteria-driven biohybrid microswimmers (bacteriabots), which integrate motile bacterial cells and functional synthetic cargo parts (e.g., microparticles encapsulating drug), are recently studied for targeted drug delivery. However, adhesion of such bacteriabots to the tissues on the site of a disease (which can increase the drug delivery efficiency) is not studied yet. Here, this paper proposes an approach to attach bacteriabots to certain types of epithelial cells (expressing mannose on the membrane), based on the affinity between lectin molecules on the tip of bacterial type I pili and mannose molecules on the epithelial cells...
June 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
https://www.readbyqxmd.com/read/28638403/jaburetox-update-on-a-urease-derived-peptide
#14
REVIEW
Arlete Beatriz Becker-Ritt, Camila Saretta Portugal, Célia Regina Carlini
Urease from Canavalia ensiformis seeds was the first enzyme ever to be crystallized, in 1926. These proteins, found in plants, bacteria and fungi, present different biological properties including catalytic hydrolysis of urea, and also enzyme-independent activities, such as induction of exocytosis, pro-inflammatory effects, neurotoxicity, antifungal and insecticidal properties. Urease is toxic to insects and fungi per se but part of this toxicity relies on an internal peptide (~11 kDa), which is released upon digestion of the protein by insect enzymes...
2017: Journal of Venomous Animals and Toxins Including Tropical Diseases
https://www.readbyqxmd.com/read/28638093/fatty-acid-composition-and-phospholipid-types-used-in-infant-formulas-modifies-the-establishment-of-human-gut-bacteria-in-germ-free-mice
#15
Rikke Guldhammer Nejrup, Tine Rask Licht, Lars Ingvar Hellgren
Human milk fat contains high concentrations of medium-chained fatty acids (MCFA) and triacylglycerols emulsified by a sphingomyelin-rich phospholipid membrane (milk phospholipids, MPL). Infant formula comprises mainly long-chained fatty acids (LCFA) emulsified with dairy proteins and soy lecithin (SL) lacking sphingomyelin. Sphingomyelin content and saturation level of phospholipids affect the gut lipase activity, which alters the concentrations of lipid hydrolysis products in ileum and colon, and hereby putatively affects the competitive advantage of specific gut bacteria...
June 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28638070/thioesterase-ybgc-affects-motility-by-modulating-c-di-gmp-levels-in-shewanella-oneidensis
#16
Tong Gao, Qiu Meng, Haichun Gao
Because of ubiquity of thioesters, thioesterases play a critical role in metabolism, membrane biosynthesis, signal transduction, and gene regulation. In many bacteria, YbgC is such an enzyme, whose coding gene mostly resides in the tol-pal cluster. Although all other proteins encoded in the tol-pal cluster are clearly involved in maintaining cell envelope integrity and cell division, little is known about the physiological role of YbgC. In this study, we identify in Shewanella oneidensis, a γ-proteobacterium used as a research model for environmental microbes, YbgC as a motility regulator...
June 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28636623/the-basolateral-vesicle-sorting-machinery-and-basolateral-proteins-are-recruited-to-the-site-of-enteropathogenic-e-coli-microcolony-growth-at-the-apical-membrane
#17
Gitte A Pedersen, Helene H Jensen, Anne-Sofie B Schelde, Charlotte Toft, Hans N Pedersen, Maj Ulrichsen, Frédéric H Login, Manuel R Amieva, Lene N Nejsum
Foodborne Enteropathogenic Escherichia coli (EPEC) infections of the small intestine cause diarrhea especially in children and are a major cause of childhood death in developing countries. EPEC infects the apical membrane of the epithelium of the small intestine by attaching, effacing the microvilli under the bacteria and then forming microcolonies on the cell surface. We first asked the question where on epithelial cells EPEC attaches and grows. Using models of polarized epithelial monolayers, we evaluated the sites of initial EPEC attachment to the apical membrane and found that EPEC preferentially attached over the cell-cell junctions and formed microcolonies preferentially where three cells come together at tricellular tight junctions...
2017: PloS One
https://www.readbyqxmd.com/read/28636601/crystal-structure-of-the-potassium-importing-kdpfabc-membrane-complex
#18
Ching-Shin Huang, Bjørn Panyella Pedersen, David L Stokes
Cellular potassium import systems play a fundamental role in osmoregulation, pH homeostasis and membrane potential in all domains of life. In bacteria, the kdp operon encodes a four-subunit potassium pump that maintains intracellular homeostasis, cell shape and turgor under conditions in which potassium is limiting. This membrane complex, called KdpFABC, has one channel-like subunit (KdpA) belonging to the superfamily of potassium transporters and another pump-like subunit (KdpB) belonging to the superfamily of P-type ATPases...
June 21, 2017: Nature
https://www.readbyqxmd.com/read/28636355/semisynthetic-flavone-derived-antimicrobials-with-therapeutic-potential-against-methicillin-resistant-staphylococcus-aureus-mrsa
#19
Shuimu Lin, Jun-Jie Koh, Thet Tun Aung, Wan Ling Wendy Sin, Fanghui Lim, Lin Wang, Rajamani Lakshminarayanan, Lei Zhou, Donald T H Tan, Derong Cao, Roger W Beuerman, Li Ren, Shouping Liu
A new series of semisynthetic flavone-based small molecules mimicking antimicrobial peptides has been designed from natural icaritin to combat drug-resistant Gram-positive bacterial infections. Compound 6 containing two arginine residues exhibited excellent antibacterial activity against Gram-positive bacteria, including MRSA, and very low toxicity to mammalian cells, resulting in a high selectivity of more than 511, comparable to that of several membrane-active antibiotics in clinical trials. Our data show for the first time that icaritin derivatives effectively kill bacteria...
June 21, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28636010/engineering-multi-functional-bacterial-outer-membrane-vesicles-as-modular-nanodevices-for-biosensing-and-bioimaging
#20
Qi Chen, Sharon Rozovsky, Wilfred Chen
Outer membrane vesicles (OMVs) are proteoliposomes derived from the outer membrane and periplasmic space of many Gram-negative bacteria including E. coli as part of their natural growth cycle. Inspired by the natural ability of E. coli to sort proteins to both the exterior and interior of OMVs, we reported here a one-pot synthesis approach to engineer multi-functionalized OMV-based sensors for both antigen binding and signal generation. SlyB, a native lipoprotein, was used a fusion partner to package nanoluciferase (Nluc) within OMVs, while a previously developed INP-Scaf3 surface scaffold was fused to the Z-domain for antibody recruiting...
June 21, 2017: Chemical Communications: Chem Comm
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