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https://www.readbyqxmd.com/read/29166667/flotillin-scaffold-activity-contributes-to-type-vii-secretion-system-assembly-in-staphylococcus-aureus
#1
Benjamin Mielich-Süss, Rabea M Wagner, Nicole Mietrach, Tobias Hertlein, Gabriella Marincola, Knut Ohlsen, Sebastian Geibel, Daniel Lopez
Scaffold proteins are ubiquitous chaperones that promote efficient interactions between partners of multi-enzymatic protein complexes; although they are well studied in eukaryotes, their role in prokaryotic systems is poorly understood. Bacterial membranes have functional membrane microdomains (FMM), a structure homologous to eukaryotic lipid rafts. Similar to their eukaryotic counterparts, bacterial FMM harbor a scaffold protein termed flotillin that is thought to promote interactions between proteins spatially confined to the FMM...
November 22, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/29166602/mucus-detachment-by-host-metalloprotease-meprin-%C3%AE-requires-shedding-of-its-inactive-pro-form-which-is-abrogated-by-the-pathogenic-protease-rgpb
#2
Rielana Wichert, Anna Ermund, Stefanie Schmidt, Matthias Schweinlin, Miroslaw Ksiazek, Philipp Arnold, Katharina Knittler, Frederike Wilkens, Barbara Potempa, Björn Rabe, Marit Stirnberg, Ralph Lucius, Jörg W Bartsch, Susanna Nikolaus, Maren Falk-Paulsen, Philip Rosenstiel, Marco Metzger, Stefan Rose-John, Jan Potempa, Gunnar C Hansson, Peter J Dempsey, Christoph Becker-Pauly
The host metalloprotease meprin β is required for mucin 2 (MUC2) cleavage, which drives intestinal mucus detachment and prevents bacterial overgrowth. To gain access to the cleavage site in MUC2, meprin β must be proteolytically shed from epithelial cells. Hence, regulation of meprin β shedding and activation is important for physiological and pathophysiological conditions. Here, we demonstrate that meprin β activation and shedding are mutually exclusive events. Employing ex vivo small intestinal organoid and cell culture experiments, we found that ADAM-mediated shedding is restricted to the inactive pro-form of meprin β and is completely inhibited upon its conversion to the active form at the cell surface...
November 21, 2017: Cell Reports
https://www.readbyqxmd.com/read/29166022/dynamics-of-ompf-trimer-formation-in-the-bacterial-outer-membrane-of-escherichia-coli
#3
Huilin Ma, Aliza Khan, Shikha Nangia
The self-assembly of outer membrane protein F (OmpF) in the outer membrane of Escherichia coli Gram-negative bacteria was studied using multiscale molecular dynamics simulations. To facilitate the long timescale required for protein assembly, coarse-grained parameterization of E. coli outer membrane lipids was first developed. The OmpF monomers formed stable dimers at specific protein-protein interactions sites irrespective of the lipid membrane environment. The dimer intermediate was asymmetric but provided a template to form a symmetric trimer...
November 22, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29164103/the-human-antimicrobial-peptides-dermcidin-and-ll-37-show-novel-distinct-pathways-in-membrane-interactions
#4
REVIEW
Kornelius Zeth, Enea Sancho-Vaello
Mammals protect themselves from inflammation triggered by microorganisms through secretion of antimicrobial peptides (AMPs). One mechanism by which AMPs kill bacterial cells is perforating their membranes. Membrane interactions and pore formation were investigated for α-helical AMPs leading to the formulation of three basic mechanistic models: the barrel stave, toroidal, and carpet model. One major drawback of these models is their simplicity. They do not reflect the real in vitro and in vivo conditions. To challenge and refine these models using a structure-based approach we set out to investigate how human cathelicidin (LL-37) and dermcidin (DCD) interact with membranes...
2017: Frontiers in Chemistry
https://www.readbyqxmd.com/read/29164074/systemic-responses-of-multidrug-resistant-pseudomonas-aeruginosa-and-acinetobacter-baumannii-following-exposure-to-the-antimicrobial-peptide-cathelicidin-bf-imply-multiple-intracellular-targets
#5
Cunbao Liu, Bin Shan, Jialong Qi, Yanbing Ma
Cathelicidin-BF, derived from the banded krait (Bungarus fasciatus), is a typically cationic, amphiphilic and α-helical antimicrobial peptide (AMP) with 30 amino acids that exerts powerful effects on multidrug-resistant (MDR) clinical isolates, including Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae, but whether it targets plasma membranes or intracellular targets to kill bacteria is still controversial. In the present study, we demonstrated that the disruption of bacterial membranes with high concentrations of cathelicidin-BF was the cause of bacterial death, as with conventional antibiotics at high concentrations...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/29164073/streptococcus-equi-subsp-zooepidemicus-invades-and-survives-in-epithelial-cells
#6
Bolette Skive, Manfred Rohde, Gabriella Molinari, Thomas Hartig Braunstein, Anders M Bojesen
Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) is an opportunistic pathogen of several species including humans. S. zooepidemicus is found on mucus membranes of healthy horses, but can cause acute and chronic endometritis. Recently S. zooepidemicus was found able to reside in the endometrium for prolonged periods of time. Thus, we hypothesized that an intracellular phase may be part of the S. zooepidemicus pathogenesis and investigated if S. zooepidemicus was able to invade and survive inside epithelial cells...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/29164053/synergistic-protective-activity-of-tumor-specific-epitopes-engineered-in-bacterial-outer-membrane-vesicles
#7
Alberto Grandi, Michele Tomasi, Ilaria Zanella, Luisa Ganfini, Elena Caproni, Laura Fantappiè, Carmela Irene, Luca Frattini, Samine J Isaac, Enrico König, Francesca Zerbini, Simona Tavarini, Chiara Sammicheli, Fabiola Giusti, Ilaria Ferlenghi, Matteo Parri, Guido Grandi
Introduction: Bacterial outer membrane vesicles (OMVs) are naturally produced by all Gram-negative bacteria and, thanks to their plasticity and unique adjuvanticity, are emerging as an attractive vaccine platform. To test the applicability of OMVs in cancer immunotherapy, we decorated them with either one or two protective epitopes present in the B16F10EGFRvIII cell line and tested the protective activity of OMV immunization in C57BL/6 mice challenged with B16F10EGFRvIII. Materials and methods: The 14 amino acid B cell epitope of human epidermal growth factor receptor variant III (EGFRvIII) and the mutation-derived CD4+ T cell neo-epitope of kif18b gene (B16-M30) were used to decorate OMVs either alone or in combination...
2017: Frontiers in Oncology
https://www.readbyqxmd.com/read/29163515/nanobody-based-delivery-systems-for-diagnosis-and-targeted-tumor-therapy
#8
REVIEW
Yaozhong Hu, Changxiao Liu, Serge Muyldermans
The development of innovative targeted therapeutic approaches are expected to surpass the efficacy of current forms of treatments and cause less damage to healthy cells surrounding the tumor site. Since the first development of targeting agents from hybridoma's, monoclonal antibodies (mAbs) have been employed to inhibit tumor growth and proliferation directly or to deliver effector molecules to tumor cells. However, the full potential of such a delivery strategy is hampered by the size of mAbs, which will obstruct the targeted delivery system to access the tumor tissue...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/29163512/carboxyl-terminal-residues-n478-and-v479-required-for-the-cytolytic-activity-of-listeriolysin-o-play-a-critical-role-in-listeria-monocytogenes-pathogenicity
#9
Changyong Cheng, Li Jiang, Tiantian Ma, Hang Wang, Xiao Han, Jing Sun, Yongchun Yang, Zhongwei Chen, Huifei Yu, Yi Hang, Fengdan Liu, Bosen Wang, Weihuan Fang, Huarong Huang, Chun Fang, Chang Cai, Nancy Freitag, Houhui Song
Listeria monocytogenes is a facultative intracellular pathogen that secretes the cytolysin listeriolysin O (LLO), which enables the bacteria to cross the phagosomal membrane. L. monocytogenes regulates LLO activity in the phagosome and minimizes its activity in the host cytosol. Mutants that fail to compartmentalize LLO activity are cytotoxic and have attenuated virulence. Here, we showed that residues N478 and V479 of LLO are required for LLO hemolytic activity and bacterial virulence. A single N478A mutation (LLON478A) significantly increased the hemolytic activity of LLO at a neutral pH, while no difference was observed at the optimum acidic pH, compared with wild-type LLO...
2017: Frontiers in Immunology
https://www.readbyqxmd.com/read/29163452/the-opportunistic-pathogen-vibrio-vulnificus-produces-outer-membrane-vesicles-in-a-spatially-distinct-manner-related-to-capsular-polysaccharide
#10
Cheri M Hampton, Ricardo C Guerrero-Ferreira, Rachel E Storms, Jeannette V Taylor, Hong Yi, Paul A Gulig, Elizabeth R Wright
Vibrio vulnificus, a bacterial species that inhabits brackish waters, is an opportunistic pathogen of humans. V. vulnificus infections can cause acute gastroenteritis, invasive septicemia, tissue necrosis, and potentially death. Virulence factors associated with V. vulnificus include the capsular polysaccharide (CPS), lipopolysaccharide, flagellum, pili, and outer membrane vesicles (OMVs). The aims of this study were to characterize the morphology of V. vulnificus cells and the formation and arrangement of OMVs using cryo-electron microscopy (cryo-EM)...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29163385/synergistic-response-of-rifampicin-with-hydroperoxides-on-mycobacterium-a-mechanistic-study
#11
Yesha S Patel, Sarika Mehra
Prolonged chemotherapy as well as rapid development of antimicrobial resistance are two of the major concerns for treatment of mycobacterial infections. To enhance the effectiveness of current drug regimens, search for compounds having synergistic interaction with anti-mycobacterial drugs has become indispensable. Here, we have investigated the intervention by oxidative stress, a major factor in mycobacterial pathogenesis, in combination with rifampicin (RIF), a first-line drug used against Mycobacterium tuberculosis...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29163381/functional-characterization-of-acinetobacter-baumannii-lacking-the-rna-chaperone-hfq
#12
Han-Yueh Kuo, Hsuan-Hao Chao, Po-Cheng Liao, Long Hsu, Kai-Chih Chang, Chi-Hua Tung, Chang-Hua Chen, Ming-Li Liou
The RNA chaperone Hfq is involved in the riboregulation of diverse genes via small RNAs. Recent studies have demonstrated that Hfq contributes to the stress response and the virulence of several pathogens, and the roles of Hfq vary among bacterial species. Here, we attempted to elucidate the role of Hfq in Acinetobacter baumannii ATCC 17978. In the absence of hfq, A. baumannii exhibited retarded cell growth and was highly sensitive to environmental stress, including osmotic and oxidative pressure, pH, and temperature...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29161569/denitrification-of-landfill-leachate-under-different-hydraulic-retention-time-in-a-two-stage-anoxic-oxic-combined-membrane-bioreactor-process-performances-and-bacterial-community
#13
Jianbo Liu, Panyue Zhang, Haibo Li, Yuan Tian, Siyu Wang, Yonghui Song, Guangming Zeng, Chen Sun, Zhiyong Tian
Two-stage anoxic/oxic combined membrane bioreactor (A/O-A/O-MBR) process was used to treat leachate generated from Shenyang Laohuchong landfill, and the effect of hydraulic retention time (HRT) was studied. A long HRT of 9 d and a short HRT of 5 d showed negative effect on the stability of process, resulting in a higher organic concentration of effluent than that with a HRT of 7 d, while the highest removal of chemical oxygen demand (COD), ammonia (NH4(+)-N) and total nitrogen (TN) were achieved with a HRT of 7 d, which was 82...
November 11, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/29161263/the-nucleoid-as-a-scaffold-for-the-assembly-of-bacterial-signaling-complexes
#14
Audrey Moine, Leon Espinosa, Eugenie Martineau, Mutum Yaikhomba, P J Jazleena, Deborah Byrne, Emanuele G Biondi, Eugenio Notomista, Matteo Brilli, Virginie Molle, Pananghat Gayathri, Tâm Mignot, Emilia M F Mauriello
The FrzCD chemoreceptor from the gliding bacterium Myxococcus xanthus forms cytoplasmic clusters that occupy a large central region of the cell body also occupied by the nucleoid. In this work, we show that FrzCD directly binds to the nucleoid with its N-terminal positively charged tail and recruits active signaling complexes at this location. The FrzCD binding to the nucleoid occur in a DNA-sequence independent manner and leads to the formation of multiple distributed clusters that explore constrained areas...
November 21, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/29160808/interplay-between-colistin-resistance-virulence-and-fitness-in-acinetobacter-baumannii
#15
REVIEW
Gabriela Jorge Da Silva, Sara Domingues
Acinetobacter baumannii is an important opportunistic nosocomial pathogen often resistant to multiple antibiotics classes. Colistin, an "old" antibiotic, is now considered a last-line treatment option for extremely resistant isolates. In the meantime, resistance to colistin has been reported in clinical A. baumannii strains. Colistin is a cationic peptide that disrupts the outer membrane (OM) of Gram-negative bacteria. Colistin resistance is primarily due to post-translational modification or loss of the lipopolysaccharide (LPS) molecules inserted into the outer leaflet of the OM...
November 21, 2017: Antibiotics
https://www.readbyqxmd.com/read/29160602/mitochondrial-ribosome-bl34-mutants-present-diminished-translation-of-cytochrome-c-oxidase-subunits
#16
Raquel Fonseca Guedes-Monteiro, José Ribamar Ferreira-Junior, Lucas Bleicher, Francisco G Nóbrega, Antoni Barrientos, Mario H Barros
Saccharomyces cerevisiae mitoribosomes are specialized in the translation of a few number of highly hydrophobic membrane proteins, components of the oxidative phosphorylation system. Mitochondrial characteristics, such as the membrane system and its redox state driven mitoribosomes evolution through great diversion from their bacterial and cytosolic counterparts. Therefore, mitoribosome presents a considerable number of mitochondrial-specific proteins, as well as new protein extensions. In this work we characterize temperature sensitive mutants of the subunit bL34 present in the 54S large subunit...
November 21, 2017: Cell Biology International
https://www.readbyqxmd.com/read/29160079/a-comprehensive-mass-spectrometric-survey-of-streptococcus-pyogenes-subcellular-proteomes
#17
Laura Wilk, Lotta Happonen, Johan Malmström, Heiko Herwald
Streptococcus pyogenes is a major global health burden causing a wide variety of diseases. As a vaccine against this bacterium is still lacking, vaccine candidates or antimicrobial therapies are urgently needed. Here, we use an invasive and clinical relevant streptococcal M1 serotype in order to characterise the bacterial proteome in-depth. An elaborate fractionation technique is employed to separate the different cell fractions followed by shotgun mass spectrometry analysis, allowing us to confirm the expression of nearly two thirds (1022) of the 1690 open reading frames predicted for the streptococcal M1 reference proteome...
November 21, 2017: Journal of Proteome Research
https://www.readbyqxmd.com/read/29160034/free-living-chemoautotrophic-and-particle-attached-heterotrophic-prokaryotes-dominate-microbial-assemblages-along-a-pelagic-redox-gradient
#18
Elizabeth A Suter, Maria Pachiadaki, Gordon T Taylor, Yrene Astor, Virginia P Edgcomb
Using the anoxic Cariaco Basin as a natural laboratory, particle association of bacterial and archaeal taxa was assessed by iTag sequencing and qPCR gene assays of samples spanning an oxic-anoxic-euxinic gradient. Ten to twelve percent of all bacterial and archaeal cells were found in the particle-associated (PA) fraction, operationally defined as prokaryotes captured on 2.7µm membranes. Both redox condition and size fraction segregated bacterial taxa. Archaeal taxa varied according to redox conditions, but were similar between size fractions...
November 21, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/29158430/characterization-of-stress-and-innate-immunity-resistance-of-wild-type-and-%C3%AE-p66-borrelia-burgdorferi
#19
Michael W Curtis, Beth L Hahn, Kai Zhang, Chunhao Li, Richard T Robinson, Jenifer Coburn
Borrelia burgdorferi is a causative agent of Lyme disease, the most common arthropod-borne disease in the United States. B. burgdorferi evades host immune defenses to establish a persistent, disseminated infection. Previous work showed that P66-deficient B. burgdorferi (Δp66) is cleared quickly after inoculation in mice. We demonstrate that Δp66 is rapidly cleared from the skin inoculation site prior to dissemination. The rapid clearance of Δp66 is not due to inherent defects in multiple properties that might affect infectivity: bacterial outer membrane integrity, motility, chemotactic response, or nutrient acquisition...
November 20, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/29158275/a-simplified-derivative-of-human-defensin-5-with-potent-efficiency-against-multidrug-resistant-acinetobacter-baumannii
#20
Cheng Wang, Gaomei Zhao, Song Wang, Yin Chen, Yali Gong, Shilei Chen, Yang Xu, Mengjia Hu, Xinmiao Wang, Hao Zeng, Aiping Wang, Dengqun Liu, Yongping Su, Tianmin Cheng, Fang Chen, Junping Wang
The increasing incidence of multidrug-resistant Acinetobacter baumannii (MDRAb) infections worldwide has necessitated the development of novel antibiotics. Human defensin 5 (HD5) is an endogenous peptide with a complex architecture and antibacterial activity against MDRAb In the present study, we attempted to simplify the structure of HD5 by removing disulfide bonds. We found that the Cys2-4 bond was most indispensable for HD5 to inactivate MDRAb, although the antibacterial activity of the derivative was significantly attenuated...
November 20, 2017: Antimicrobial Agents and Chemotherapy
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