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bacterial membrane

Raquel Girardello, Marina Visconde, Rodrigo Cayô, Regina Célia Bressan Queiroz de Figueiredo, Marcelo Alves da Silva Mori, Nilton Lincopan, Ana Cristina Gales
Polymyxins have become drugs of last resort for treatment of multi-drug resistant (MDR) Gram-negative infections. However, the mechanisms of resistance to this compound have not been completely elucidated. In this study, we evaluated the mechanisms of resistance to this antimicrobial in two A. baumannii clinical isolates, respectively, susceptible (A027) and resistant (A009) to polymyxin B before and after polymyxin B exposure (A027(ind) and A009(ind)). The pmrAB and lpxACD were sequenced and their transcriptional levels were analyzed by qRT-PCR...
October 8, 2016: Diagnostic Microbiology and Infectious Disease
Abhishek Bhattacherjee, Yuliya Hrynets, Mirko Betti
Fructosazine is a polyhydroxyalkylpyrazine recently reported to have antimicrobial activity against heat-resistant E. coli AW 1.7. This study investigated fructosazine's antimicrobial mechanism of action and compared it to that of riboflavin. Fructosazine-acetic acid was effective in permeabilizing the outer membrane based on an evaluation of bacterial membrane integrity using 1-N-phenyl-1-naphthylamine and propidium iodide. The uptake of fructosazine by E. coli was pH-dependent with a greater uptake at pH 5 compared to pH 7 for all times throughout 16 h, except 2, 3 and 10 h...
October 25, 2016: Journal of Agricultural and Food Chemistry
Juke S Lolkema, Dirk Jan Slotboom
The recently determined crystal structure of the bacterial Na(+)-citrate symporter CitS provides unexpected structural and mechanistic insights. The protein has a fold that has not been seen in other proteins, but the oligomeric state, domain organization and proposed transport mechanism strongly resemble those of the sodium-dicarboxylate symporter vcINDY, and the putative exporters YdaH and MtrF, thus hinting at convergence in structure and function. CitS and the related proteins are predicted to translocate their substrates by an elevator-like mechanism, in which a compact transport domain slides up and down through the membrane while the dimerization domain is stably anchored...
October 21, 2016: Current Opinion in Structural Biology
Vera Pader, Sanika Hakim, Kimberley L Painter, Sivaramesh Wigneshweraraj, Thomas B Clarke, Andrew M Edwards
Daptomycin is a bactericidal antibiotic of last resort for serious infections caused by methicillin-resistant Staphylococcus aureus (MRSA)(1,2). Although resistance is rare, treatment failure can occur in more than 20% of cases(3,4) and so there is a pressing need to identify and mitigate factors that contribute to poor therapeutic outcomes. Here, we show that loss of the Agr quorum-sensing system, which frequently occurs in clinical isolates, enhances S. aureus survival during daptomycin treatment. Wild-type S...
October 24, 2016: Nature Microbiology
Ya Gao, Yingbo Wang, Yimin Wang, Wenguo Cui
A major goal of biomimetics is the development of chemical compositions and structures that simulate the extracellular matrix. In this study, gelatin-based electrospun composite fibrous membranes were prepared by electrospinning to generate bone scaffold materials. The gelatin-based multicomponent composite fibers were fabricated using co-electrospinning, and the composite fibers of chitosan (CS), gelatin (Gel), hydroxyapatite (HA), and graphene oxide (GO) were successfully fabricated for multi-function characteristics of biomimetic scaffolds...
October 21, 2016: Marine Drugs
Nadine Czekalski, Stefanie Imminger, Elisabeth Salhi, Marjan Veljkovic, Karolin Kleffel, David Drissner, Frederik Hammes, Helmut Bürgmann, Urs von Gunten
Ozone, a strong oxidant and disinfectant, seems ideal to cope with future challenges of water treatment, such as micropollutants, multiresistant bacteria (MRB) and even intracellular antibiotic resistance genes (ARG), but information on the latter is scarce. In ozonation experiments we simultaneously determined kinetics and dose-dependent inactivation of Escherichia coli and its plasmid-encoded sulfonamide resistance gene sul1 in different water matrixes. Effects in E. coli were compared to an autochthonous wastewater community...
October 24, 2016: Environmental Science & Technology
Jing Lu, Zhenning Wang, Mengrou Ren, Guoren Huang, Baochen Fang, Xiujuan Bu, Yanhui Liu, Shuang Guan
In the study, we investigated the antibacterial activity and mechanism of gallic acid against Aeromonas hydrophila and Aeromonas sobria. Gallic acid showed strong antimicrobial activity against the two bacteria. Furthermore, the antibacterial mechanism of gallic acid (0, 3, 6, 12 mM ) was performed by membrane integrity assay and scanning electron microscopy (SEM) assay. The results showed that gallic acid notably increased the released material absorption value at 260, 280 nm and electric conductivity in a dose-dependent manner...
October 22, 2016: Current Pharmaceutical Biotechnology
François Vromman, Stéphanie Perrinet, Lena Gehre, Agathe Subtil
Chlamydiae are Gram negative bacteria that develop exclusively inside eukaryotic host cells, within a membrane-bounded compartment. Members of the family Chlamydiaceae, such as Chlamydia trachomatis, are pathogenic species infecting vertebrates. They have a very reduced genome and exploit the capacities of their host for their own development, mainly through the secretion of proteins tailored to interfere with eukaryotic processes, called effector proteins. All Chlamydiaceae possess genes coding for four to five effectors that share a domain of unknown function (DUF582)...
2016: Frontiers in Cellular and Infection Microbiology
Shin-Ichi Yokobori, Yoshiki Nakajima, Satoshi Akanuma, Akihiko Yamagishi
Bacteria and Eukarya have cell membranes with sn-glycerol-3-phosphate (G3P), whereas archaeal membranes contain sn-glycerol-1-phosphate (G1P). Determining the time at which cells with either G3P-lipid membranes or G1P-lipid membranes appeared is important for understanding the early evolution of terrestrial life. To clarify this issue, we reconstructed molecular phylogenetic trees of G1PDH (G1P dehydrogenase; EgsA/AraM) which is responsible for G1P synthesis and G3PDHs (G3P dehydrogenase; GpsA and GlpA/GlpD) and glycerol kinase (GlpK) which is responsible for G3P synthesis...
2016: Archaea: An International Microbiological Journal
Nathan J Alves, Kendrick B Turner, Kyle A DiVito, Michael A Daniele, Scott A Walper
To facilitate the rapid purification of bacterial outer membrane vesicles (OMVs), we developed two plasmid constructs that utilize a truncated, transmembrane protein to present an exterior histidine repeat sequence. We chose OmpA, a highly abundant porin protein, as the protein scaffold and utilized the lac promoter to allow for inducible control of the epitope-presenting construct. OMVs containing mutant OmpA-His6 were purified directly from Escherichia coli culture media on an immobilized metal affinity chromatography (IMAC) Ni-NTA resin...
October 20, 2016: Research in Microbiology
Lingling Zhang, Huan Qi, Zhengxu Yan, Yu Gu, Weiqiang Sun, Abraham Amenay Zewde
The present study evaluated inactivation efficiency of a sonophotocatalytic process using ZnO nanofluids including ultrasonic parameters such as power density, frequency and time. The result showed that inactivation efficiency was increased by 20% when ultrasonic irradiation was combined with photocatalytic process in the presence of natural light. Comparison of inactivation efficiency in photocatalytic, ultrasonic and sonocatalytic processes using Escherichia coli as a model bacteria identified that inactivation efficiencies are shown in the following order: ultrasonic irradiation<sonocatalysis<photocatalysis<sonophotocatalysis...
January 2017: Ultrasonics Sonochemistry
Masahiro Ito, Yuka Takahashi
Prior to 2008, all previously studied conventional bacterial flagellar motors appeared to utilize either H(+) or Na(+) as coupling ions. Membrane-embedded stator complexes support conversion of energy using transmembrane electrochemical ion gradients. The main H(+)-coupled stators, known as MotAB, differ from Na(+)-coupled stators, PomAB of marine bacteria, and MotPS of alkaliphilic Bacillus. However, in 2008, a MotAB-type flagellar motor of alkaliphilic Bacillus clausii KSM-K16 was revealed as an exception with the first dual-function motor...
October 22, 2016: Extremophiles: Life Under Extreme Conditions
Johnson Lin
Quantification of gene expression of Acinetobacter strain Y under 1000 mg/l of phenol was investigated using qPCR and proteomic analyses. The results show that Acinetobacter strain Y utilized 100 % of phenol within 18 h of exposure. The results of qPCR and proteomic analyses demonstrate a sequential expression of phenol-degrading genes of Acinetobacter strain Y via the ortho-pathway followed by the β-ketoadipate pathway. Many stress-responsive proteins such as chaperones, chaperonins, porins and the enzymes involved in the signal transduction pathway were upregulated especially in the early stage...
October 22, 2016: Archives of Microbiology
Susanne E Pors, Ida J Pedersen, Ragnhild Bager Skjerning, Ida C N Thøfner, Gry Persson, Anders M Bojesen
Gallibacterium anatis causes infections in the reproductive tract of egg-laying hens and induce increased mortality and decreased egg production. New prophylactic measures are needed in order to improve animal welfare and production efficiency. Bacterial outer membrane vesicles (OMVs) have previously shown promising results in protection against infections and we hypothesized that OMVs could serve as an immunogen to protect egg-laying hens against G. anatis. To investigate the immunogenic potential of G. anatis OMVs, two in vivo studies in egg-laying hens were made...
November 15, 2016: Veterinary Microbiology
Xiaxia Meng, Dengwu Li, Dan Zhou, Dongmei Wang, Qiaoxiao Liu, Sufang Fan
ETHNOPHARMACOLOGICAL RELEVANCE: Juniperus rigida is used as Tibetan and Mongolian medicine in China for the treatment of rheumatoid arthritis, nephritis, brucellosis and other various inflammatory diseases. AIM OF THE STUDY: To evaluate antibacterial potential of essential oils from J. rigida leaves against Klebsiella pneumoniae and to examine its possible related mechanisms. The study was undertaken in order to scientifically validate the traditional use of J. rigida...
October 18, 2016: Journal of Ethnopharmacology
Florian Graef, Branko Vukosavljevic, Jean-Philippe Michel, Marius Wirth, Oliver Ries, Chiara De Rossi, Maike Windbergs, Véronique Rosilio, Christian Ducho, Sarah Gordon, Claus-Michael Lehr
Gram-negative bacteria possess a unique and complex cell envelope, composed of an inner and outer membrane separated by an intermediate cell wall-containing periplasm. This tripartite structure acts intrinsically as a significant biological barrier, often limiting the permeation of anti-infectives, and so preventing such drugs from reaching their target. Furthermore, identification of the specific permeation-limiting envelope component proves difficult in the case of many anti-infectives, due to the challenges associated with isolation of individual cell envelope structures in bacterial culture...
October 18, 2016: Journal of Controlled Release: Official Journal of the Controlled Release Society
Yu Cheng, Srinivasa Rao Avula, Wei-Wei Gao, Dinesh Addla, Vijai Kumar Reddy Tangadanchu, Ling Zhang, Jian-Mei Lin, Cheng-He Zhou
A series of new potentially multi-targeting antimicrobial 2-aminothiazolyl quinolones were designed, synthesized and characterized by (1)H NMR, (13)C NMR, IR, MS and HRMS spectra. Bioactive assay manifested that some of the prepared compounds showed moderate to good antibacterial and antifungal activities. Noticeably, compound 10f could effectively inhibit the growth of B. typhi and MRSA with MIC values of 1 and 8 μg/mL, respectively. Experimental results revealed that compound 10f was membrane-active and had the ability to rapidly kill the tested strains and effectively prevent the development of bacterial resistance...
October 7, 2016: European Journal of Medicinal Chemistry
Pradipta Ranjan Rauta, Sarbani Ashe, Debasis Nayak, Bismita Nayak
Virulence-related outer membrane proteins (Omps) are expressed in bacteria (Gram-negative) such as V. cholerae and are vital to bacterial invasion in to eukaryotic cell and survival within macrophages that could be best candidate for development of vaccine against V. cholerae. Applying in silico approaches, the 3-D model of the Omp was developed using Swiss model server and validated byProSA and Procheck web server. The continuous stretch of amino acid sequences 26mer: RTRSNSGLLTWGDKQTITLEYGDPAL and 31mer: FFAGGDNNLRGYGYKSISPQDASGALTGAKY having B-cell binding sites were selected from sequence alignment after B cell epitopes prediction by BCPred and AAP prediction modules of BCPreds...
October 12, 2016: Computational Biology and Chemistry
Narges Abdali, Jerry Matthew Parks, Keith Haynes, Julie L Chaney, Adam T Green, David Wolloscheck, John K Walker, Valentin V Rybenkov, Jerome Yves Baudry, Jeremy C Smith, Helen I Zgurskaya
Antibiotic resistance is a major threat to human welfare. Inhibitors of multidrug efflux pumps (EPIs) are promising alternative therapeutics that could revive activities of antibiotics and reduce bacterial virulence. Identification of new druggable sites for inhibition is critical for development of effective EPIs, especially in light of constantly emerging resistance. Here, we describe EPIs that interact with periplasmic membrane fusion proteins, critical components of efflux pumps that are responsible for the activation of the transporter and the recruitment of the outer-membrane channel...
October 21, 2016: ACS Infectious Diseases
Ishita Mukherjee, Abhijit Chakraborty, Saikat Chakrabarti
BACKGROUND: An active immune surveillance and a range of barriers to infection allow the host to effectively eliminate microbial pathogens. However, pathogens may use diverse strategies to subdue such host defences. For instance, one such mechanism is the use of leucine-rich repeat (LRR) proteins by pathogens (microbial) to cause infection. In this study, we aimed at identifying novel virulence factor(s) in Leishmania donovani, based on the possibility of lateral gene transfers of bacterial virulence factor(s) to L...
October 21, 2016: Parasites & Vectors
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