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https://www.readbyqxmd.com/read/28822159/-effect-of-sodium-houttuyfonate-in-combination-with-erythromycin-on-luxs-agr-rna%C3%A2-of-staphylococus-epidermidis
#1
Gan-Fei Xu, Jing-Jing Wang, Da-Qiang Wu, Yan Guan
Quorum sensing of bacteria and its specific gene expression regulation have a very important role in bacterial biofilm formation. LuxS and agr are the key regulatory genes in quorum sensing of Staphylococcus epidermidis, and RNA Ⅲ is the effector molecule of agr system. In order to evaluate the effects of sodium houttuyfonate in combination with erythromycin on the transcription level of S. epidermidis, serial dilution method was used to determine the MIC of sodium houttuyfonate, erythromycin and vancomycin on S...
June 2017: Zhongguo Zhong Yao za Zhi, Zhongguo Zhongyao Zazhi, China Journal of Chinese Materia Medica
https://www.readbyqxmd.com/read/28821717/promysalin-is-a-salicylate-containing-antimicrobial-with-a-cell-membrane-disrupting-mechanism-of-action-on-gram-positive-bacteria
#2
Rahul D Kaduskar, Giulia Della Scala, Zaaima J H Al Jabri, Stefania Arioli, Loana Musso, Marco R Oggioni, Sabrina Dallavalle, Diego Mora
Promysalin was previously described as a narrow spectrum molecule with a unique species-specific activity against Pseudomonas aeruginosa. Here we demonstrate that promysalin is active against Gram-positive and Gram-negative bacteria using a microdilution assay. Promysalin acts on Gram-positive bacteria with a mechanism of action involving cell membrane damage with leakage of intracellular components. The evaluation of MICs and MBCs on 11 promysalin analogs, synthesized utilizing diverted total synthesis, allowed the identification of the structural moieties potentially involved in cell membrane interaction and damage...
August 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28821027/preparation-characterization-and-antibacterial-activity-of-oxidized-%C3%AE%C2%BA-carrageenan
#3
Mingjin Zhu, Liming Ge, Yongbo Lyu, Yaxin Zi, Xinying Li, Defu Li, Changdao Mu
The oxidized κ-carrageenans with different oxidation levels were prepared through the hydrogen peroxide and copper sulfate redox system. The oxidation level of oxidized κ-carrageenan was successfully controlled by adjusting the dosage of hydrogen peroxide. The results showed that the microtopography of oxidized κ-carrageenan changed from rough granules to smooth flakes, mainly resulting from the easily melting property of oxidized κ-carrageenan induced by introduced carboxyl and aldehyde groups. Especially, the antibacterial activity of oxidized κ-carrageenans against Gram-positive bacteria (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) was systematically investigated...
October 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28820900/secy-seca-fusion-protein-retains-the-ability-to-mediate-protein-transport
#4
Yasunori Sugano, Arata Furukawa, Osamu Nureki, Yoshiki Tanaka, Tomoya Tsukazaki
In bacteria, the membrane protein complex SecY/E/G and SecA ATPase are essential for protein translocation. About 30% of newly synthesized proteins in the cytosol are targeted to and translocated across the cytoplasmic membrane by the Sec factors. Although a number of single-molecule analyses and structural studies, including the crystal structure of SecYEG complexed with SecA, have been published, the underlying molecular mechanisms and the functional oligomer states remain elusive. In this study, we constructed a fusion protein SecY-SecA, which induces the formation of the SecY-A/SecE/SecG complex (SecYAEG), to enable investigation of the molecular mechanisms by advanced single-molecule analyses...
2017: PloS One
https://www.readbyqxmd.com/read/28820387/infectious-polymorphic-toxins-delivered-by-outer-membrane-exchange-discriminate-kin-in-myxobacteria
#5
Christopher N Vassallo, Pengbo Cao, Austin Conklin, Hayley Finkelstein, Christopher S Hayes, Daniel Wall
Myxobacteria are known for complex social behaviors including outer membrane exchange (OME), in which cells exchange large amounts of outer membrane lipids and proteins upon contact. The TraA cell surface receptor selects OME partners based on a variable domain. However, traA polymorphism alone is not sufficient to precisely discriminate kin. Here, we report a novel family of OME-delivered toxins that promote kin discrimination of OME partners. These SitA lipoprotein toxins are polymorphic and widespread in myxobacteria...
August 18, 2017: ELife
https://www.readbyqxmd.com/read/28819664/antimicrobial-carbon-nanospheres
#6
Yao-Wen Jiang, Ge Gao, Xiaodong Zhang, Hao-Ran Jia, Fu-Gen Wu
Carbon nanomaterials have found numerous applications in various fields. However, their synthesis and functionalization usually require complicated procedures or tough experimental conditions. Herein, we report for the first time the synthesis of a new type of functional nanomaterial, quaternized carbon nanospheres (QCNSs), with superior antibacterial activity via a one-pot hydrothermal treatment of chitosan and hexadecylbetaine (abbreviated as BS-16). During the hydrothermal process, the direct reaction and carbonization between the amine-containing chitosan and the carboxyl-containing BS-16 were realized within only one step...
August 18, 2017: Nanoscale
https://www.readbyqxmd.com/read/28819106/identification-and-characterization-of-a-bacterial-homolog-of-chloride-intracellular-channel-clic-protein
#7
Shubha Gururaja Rao, Devasena Ponnalagu, Sowmya Sukur, Harkewal Singh, Shridhar Sanghvi, Yixiao Mei, Ding J Jin, Harpreet Singh
Chloride intracellular channels (CLIC) are non-classical ion channels lacking a signal sequence for membrane targeting. In eukaryotes, they are implicated in cell volume regulation, acidification, and cell cycle. CLICs resemble the omega class of Glutathione S-transferases (GST), yet differ from them in their ability to form ion channels. They are ubiquitously found in eukaryotes but no prokaryotic homolog has been characterized. We found that indanyloxyacetic acid-94 (IAA-94), a blocker of CLICs, delays the growth of Escherichia coli...
August 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28816600/deciphering-the-trna-dependent-lipid-aminoacylation-systems-in-bacteria-novel-components-and-structural-advances
#8
Rachel N Fields, Hervé Roy
tRNA-dependent addition of amino acids to lipids on the outer surface of the bacterial membrane results in decreased effectiveness of antimicrobials such as cationic antimicrobial peptides (CAMPs) that target the membrane, and increased virulence of several pathogenic species. After a brief introduction to CAMPs and the various bacterial resistance mechanisms used to counteract these compounds, this review focuses on recent advances in tRNA-dependent pathways for lipid modification in bacteria. Phenotypes associated with amino acid lipid modifications and regulation of their expression will also be discussed...
August 17, 2017: RNA Biology
https://www.readbyqxmd.com/read/28816463/signaling-related-mobility-changes-in-bacterial-chemotaxis-receptors-revealed-by-solid-state-nmr
#9
Maryam Kashefi, Lynmarie K Thompson
Bacteria employ remarkable membrane-bound nanoarrays to sense their environment and direct their swimming. Arrays consist of chemotaxis receptor trimers of dimers that are bridged at their membrane-distal tips by rings of two cytoplasmic proteins, a kinase CheA and a coupling protein CheW. It is not clear how ligand binding to the periplasmic domain of the receptor deactivates the CheA kinase bound to the cytoplasmic tip ~300 Å away, but the mechanism is thought to involve changes in dynamics within the cytoplasmic domain...
August 17, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28816443/characterization-of-ciprofloxacin-permeation-pathways-across-the-porin-ompc-using-metadynamics-and-a-string-method
#10
Jigneshkumar Dahyabhai Prajapati, Carlos José Fernández Solano, Mathias Winterhalter, Ulrich Kleinekathöfer
The rapid spreading of antimicrobial resistance in Gram-negative bacteria has become a major threat for humans as well as animals. As one of the main factors involved, the permeability of the outer membrane has attracted quite some attention recently. However, the knowledge regarding the translocation mechanisms for most available antibiotics is so far rather limited. Here, a theoretical study concerning the diffusion route of ciprofloxacin across the outer membrane porin OmpC from E. coli is presented. To this end, we establish a protocol to characterize meaningful permeation pathways by combining metadynamics with the zero-temperature string method...
August 17, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28816386/chemotaxis-guided-hybrid-neutrophil-micromotor-for-actively-targeted-drug-transport
#11
Jingxin Shao, Mingjun Xuan, Hongyue Zhang, Xiankun Lin, Zhiguang Wu, Qiang He
Engineering self-propelled micromotors with good biocompatibility and biodegradability for actively seeking sites of diseases and targeted drug transport remains a huge challenge. Here we demonstrate that neutrophils with intrinsic chemotaxis ability could be transformed into self-guided biohybrid motors through integrating mesoporous silica nanoparticles (MSNs) with high loading capability. To realize the compatibility of neutrophil cells with drug-loaded MSNs, bacteria membranes derived from E. coli were coated onto MSNs in advance by using a camouflaging strategy...
August 17, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28815827/outer-membrane-lipid-homeostasis-via-retrograde-phospholipid-transport-in-escherichia-coli
#12
Rahul Shrivastava, Xiang'Er Jiang, Shu-Sin Chng
Biogenesis of the outer membrane (OM) in Gram-negative bacteria, which is essential for viability, requires the coordinated transport and assembly of proteins and lipids, including lipopolysaccharides (LPS) and phospholipids (PLs), into the membrane. While pathways for LPS and OM protein assembly are well-studied, how PLs are transported to and from the OM is not clear. Mechanisms that ensure OM stability and homeostasis are also unknown. The trans-envelope Tol-Pal complex, whose physiological role has remained elusive, is important for OM stability...
August 16, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28815533/hijacking-of-membrane-contact-sites-by-intracellular-bacterial-pathogens
#13
Isabelle Derré
Intracellular bacterial pathogens have evolved sophisticated mechanisms to hijack host cellular processes to promote their survival and replication inside host cells. Over the past two decades, much attention has been given to the strategies employed by these pathogens to manipulate various vesicular trafficking pathways. But in the past 5 years, studies have brought to light that intracellular bacteria also target non-vesicular trafficking pathways. Here we review how three vacuolar pathogens, namely, Legionella, Chlamydia, and Coxiella hijack components of cellular MCS with or without the formation of stable MCS...
2017: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/28815210/lpxk-is-essential-for-growth-of-acinetobacter-baumannii-atcc-19606-relationship-to-toxic-accumulation-of-lipid-a-pathway-intermediates
#14
Jun-Rong Wei, Daryl L Richie, Mina Mostafavi, Louis E Metzger, Christopher M Rath, William S Sawyer, Kenneth T Takeoka, Charles R Dean
Acinetobacter baumannii ATCC 19606 can grow without lipid A, the major component of lipooligosaccharide. However, we previously reported that depletion of LpxH (the fourth enzyme in the lipid A biosynthetic pathway) prevented growth of this strain due to toxic accumulation of lipid A pathway intermediates. Here, we explored whether a similar phenomenon occurred with depletion of LpxK, a kinase that phosphorylates disaccharide 1-monophosphate (DSMP) at the 4' position to yield lipid IVA. An A. baumannii ATCC 19606 derivative with LpxK expression under the control of an isopropyl β-d-1-thiogalactopyranoside (IPTG)-regulated expression system failed to grow without induction, indicating that LpxK is essential for growth...
July 2017: MSphere
https://www.readbyqxmd.com/read/28814799/on-mechanism-behind-uv-a-light-enhanced-antibacterial-activity-of-gallic-acid-and-propyl-gallate-against-escherichia-coli-o157-h7
#15
Qingyang Wang, Erick Falcao de Oliveira, Solmaz Alborzi, Luis J Bastarrachea, Rohan V Tikekar
Possible mechanisms behind the enhanced antimicrobial activity of gallic acid (GA) and its ester propyl gallate (PG) in the presence of UV-A light against Escherichia coli O157:H7 were investigated. GA by itself is a mild antimicrobial and has a pro-oxidant ability. We found that the presence of UV-A light increases the uptake of GA by the bacteria. Once GA is internalized, the interaction between GA and UV-A induces intracellular ROS formation, leading to oxidative damage. Concurrently, GA + UV-A also inhibits the activity of superoxide dismutase (SOD), magnifying the imbalance of redox status of E...
August 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28814755/membrane-fouling-induced-by-ahl-mediated-soluble-microbial-product-smp-formation-by-fouling-causing-bacteria-co-cultured-with-fouling-enhancing-bacteria
#16
So Ishizaki, Ryoichi Sugiyama, Satoshi Okabe
Membrane fouling still remains a major obstacle for wider applications of membrane bioreactor (MBR), which is mainly caused by soluble microbial products (SMP). Identification of key bacteria responsible for SMP production is essential for mitigation of membrane fouling. Here, we investigated the effect of microbial interaction on membrane fouling. We measured the membrane fouling potentials of 13 bacterial strains isolated from a pilot-scale MBR treating domestic wastewater when they were cultivated as single-culture and co-culture...
August 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28813662/a-liver-capsular-network-of-monocyte-derived-macrophages-restricts-hepatic-dissemination-of-intraperitoneal-bacteria-by-neutrophil-recruitment
#17
Frederic Sierro, Maximilien Evrard, Simone Rizzetto, Michelle Melino, Andrew J Mitchell, Manuela Florido, Lynette Beattie, Shaun B Walters, Szun Szun Tay, Bo Lu, Lauren E Holz, Ben Roediger, Yik Chun Wong, Alessandra Warren, William Ritchie, Claire McGuffog, Wolfgang Weninger, David G Le Couteur, Florent Ginhoux, Warwick J Britton, William R Heath, Bernadette M Saunders, Geoffrey W McCaughan, Fabio Luciani, Kelli P A MacDonald, Lai Guan Ng, David G Bowen, Patrick Bertolino
The liver is positioned at the interface between two routes traversed by pathogens in disseminating infection. Whereas blood-borne pathogens are efficiently cleared in hepatic sinusoids by Kupffer cells (KCs), it is unknown how the liver prevents dissemination of peritoneal pathogens accessing its outer membrane. We report here that the hepatic capsule harbors a contiguous cellular network of liver-resident macrophages phenotypically distinct from KCs. These liver capsular macrophages (LCMs) were replenished in the steady state from blood monocytes, unlike KCs that are embryonically derived and self-renewing...
August 15, 2017: Immunity
https://www.readbyqxmd.com/read/28811607/localized-iron-accumulation-precedes-nucleation-and-growth-of-magnetite-crystals-in-magnetotactic-bacteria
#18
Jacques Werckmann, Jefferson Cypriano, Christopher T Lefèvre, Kassiogé Dembelé, Ovidiu Ersen, Dennis A Bazylinski, Ulysses Lins, Marcos Farina
Many magnetotactic bacteria (MTB) biomineralize magnetite crystals that nucleate and grow inside intracellular membranous vesicles that originate from invaginations of the cytoplasmic membrane. The crystals together with their surrounding membranes are referred to magnetosomes. Magnetosome magnetite crystals nucleate and grow using iron transported inside the vesicle by specific proteins. Here we address the question: can iron transported inside MTB for the production of magnetite crystals be spatially mapped using electron microscopy? Cultured and uncultured MTB from brackish and freshwater lagoons were studied using analytical transmission electron microscopy in an attempt to answer this question...
August 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28811582/a-new-class-of-hybrid-secretion-system-is-employed-in-pseudomonas-amyloid-biogenesis
#19
Sarah L Rouse, William J Hawthorne, Jamie-Lee Berry, Dror S Chorev, Sandra A Ionescu, Sebastian Lambert, Fisentzos Stylianou, Wiebke Ewert, Uma Mackie, R Marc L Morgan, Daniel Otzen, Florian-Alexander Herbst, Per H Nielsen, Morten Dueholm, Hagan Bayley, Carol V Robinson, Stephen Hare, Stephen Matthews
Gram-negative bacteria possess specialised biogenesis machineries that facilitate the export of amyloid subunits for construction of a biofilm matrix. The secretion of bacterial functional amyloid requires a bespoke outer-membrane protein channel through which unfolded amyloid substrates are translocated. Here, we combine X-ray crystallography, native mass spectrometry, single-channel electrical recording, molecular simulations and circular dichroism measurements to provide high-resolution structural insight into the functional amyloid transporter from Pseudomonas, FapF...
August 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28809546/staphylococcus-aureus-cidc-is-a-pyruvate-menaquinone-oxidoreductase
#20
Xinyan Zhang, Kenneth W Bayles, Sorin Luca
Recent studies have revealed an important role for the Staphylococcus aureus CidC enzyme in cell death during the stationary phase and in biofilm development, and have contributed to our understanding of the metabolic processes important in the induction of bacterial programmed cell death (PCD). To gain more insight into the characteristics of this enzyme, we performed an in-depth biochemical and biophysical analysis of its catalytic properties. In vitro experiments show that this flavoprotein catalyzes the oxidative decarboxylation of pyruvate to acetate and carbon dioxide...
August 15, 2017: Biochemistry
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