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bacterial membrane

V Vasilca, A Sadeghpour, S Rawson, L E Hawke, S A Baldwin, T Wilkinson, D Bannister, V L G Postis, M Rappolt, S P Muench, L J C Jeuken
Screening assays performed against membrane protein targets (e.g. phage display) are hampered by issues arising from protein expression and purification, protein stability in detergent solutions and epitope concealment by detergent micelles. Here, we have studied a fast and simple method to improve screening against membrane proteins: spherical-supported bilayer lipid membranes ("SSBLM"). SSBLMs can be quickly isolated via low-speed centrifugation and redispersed in liquid solutions while presenting the target protein in a native-like lipid environment...
March 12, 2018: Analytical Biochemistry
Konstantinos C Tsolis, Evridiki-Pandora Tsare, Georgia Orfanoudaki, Tobias Busche, Katerina Kanaki, Reshmi Ramakrishnan, Frederic Rousseau, Joost Schymkowitz, Christian Rückert, Jörn Kalinowski, Jozef Anné, Spyridoula Karamanou, Maria I Klapa, Anastassios Economou
BACKGROUND: Members of the genus Streptomyces are Gram-positive bacteria that are used as important cell factories to produce secondary metabolites and secrete heterologous proteins. They possess some of the largest bacterial genomes and thus proteomes. Understanding their complex proteomes and metabolic regulation will improve any genetic engineering approach. RESULTS: Here, we performed a comprehensive annotation of the subcellular localization of the proteome of Streptomyces lividans TK24 and developed the Subcellular Topology of Polypeptides in Streptomyces database (SToPSdb) to make this information widely accessible...
March 15, 2018: Microbial Cell Factories
Suhyung Cho, Donghui Choe, Eunju Lee, Sun Chang Kim, Bernhard Ø Palsson, Byung-Kwan Cho
Along with functional advances in the use of CRISPR/Cas9 for genome editing, endonuclease-deficient Cas9 (dCas9) has provided a versatile molecular tool for exploring gene functions. In principle, differences in cell phenotypes that result from the RNA-guided modulation of transcription levels by dCas9 are critical for inferring with gene function; however, the effect of intracellular dCas9 expression on bacterial morphology has not been systematically elucidated. Here, we observed unexpected morphological changes in Escherichia coli mediated by dCas9, which were then characterized using RNA sequencing (RNA-Seq) and chromatin immunoprecipitation sequencing (ChIP-Seq)...
March 15, 2018: ACS Synthetic Biology
Dehbia Benkerrou, Matteo Ceccarelli
One of the greatest health threats facing modern medicine is the emergence of new bacterial strains which are increasingly resistant to almost all currently available antibiotics. According to a CDC (Center for Disease Control and Prevention) report published in 2013, 63% of Acinetobacter species have been identified as Multidrug resistant strains. As for other Gram-negative bacteria, the presence of an outer membrane increases the intrinsic resistance of A. baumannii to most antibiotics. The outer membrane of A...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Hui Ye
Antimicrobial peptides are derived from the viral fusion domain of influenza virus hemagglutinin based on rational analysis of the intermolecular interaction between peptides and bacterial outer membrane. It is revealed that the isolated viral fusion domain is a negatively charged peptide HAfp1-23 that cannot effectively interact with the anionic membrane. Conversion of the native HAfp1-23 to a positively charged peptide HAfp1-23 _KK by E11K/D19K mutation can promote the peptide-membrane interaction substantially; this confers to the peptide a moderate antibacterial potency against antibiotic-resistant bacterial strains...
March 2018: Journal of Peptide Science: An Official Publication of the European Peptide Society
Meriem El Ghachi, Nicole Howe, Chia-Ying Huang, Vincent Olieric, Rangana Warshamanage, Thierry Touzé, Dietmar Weichert, Phillip J Stansfeld, Meitian Wang, Fred Kerff, Martin Caffrey
As a protective envelope surrounding the bacterial cell, the peptidoglycan sacculus is a site of vulnerability and an antibiotic target. Peptidoglycan components, assembled in the cytoplasm, are shuttled across the membrane in a cycle that uses undecaprenyl-phosphate. A product of peptidoglycan synthesis, undecaprenyl-pyrophosphate, is converted to undecaprenyl-phosphate for reuse in the cycle by the membrane integral pyrophosphatase, BacA. To understand how BacA functions, we determine its crystal structure at 2...
March 14, 2018: Nature Communications
Asghar M Razavi, George Khelashvili, Harel Weinstein
BACKGROUND: Much of the structure-based mechanistic understandings of the function of SLC6A neurotransmitter transporters emerged from the study of their bacterial LeuT-fold homologs. It has become evident, however, that structural differences such as the long N- and C-termini of the eukaryotic neurotransmitter transporters are involved in an expanded set of functional properties to the eukaryotic transporters. These functional properties are not shared by the bacterial homologs, which lack the structural elements that appeared later in evolution...
March 14, 2018: BMC Biology
Ripon Sarkar, Aritri Ghosh, Ananya Barui, Pallab Datta
Topical application of honey for tissue regeneration, has recently regained attention in clinical practice with controlled studies affirming its efficacy and indicating its role in regeneration over repair. Parallely, to overcome difficulties of applying raw honey, several product development studies like nanofibrous matrices have been reported. However, one approach concentrated on achieving highest possible honey loading in the nanofiber membranes while other studies have found that only specific honey dilutions result in differential cellular responses on wound healing and re-epithelization...
March 13, 2018: Journal of Materials Science. Materials in Medicine
Roberto Scaffaro, Francesco Lopresti, Manuela D'Arrigo, Andreana Marino, Antonia Nostro
Carvacrol (CAR) is one of the most promising essential oil components with antimicrobial activity. New technologies aimed to incorporate this active molecule into carrier matrix to improve the stability and prolong the biological activity. The goal of this study was to investigate the feasibility of incorporating CAR into electrospun membranes of poly(lactic acid) (PLA) for potential applications as active antimicrobial system. To this end, PLA membranes containing homogeneously dispersed CAR were successfully prepared and a series of systematic tests including morpho-mechanical properties, in vitro release rate, and antimicrobial/antibiofilm activities against Staphylococcus aureus and Candida albicans were carried out...
March 13, 2018: Applied Microbiology and Biotechnology
Scot P Ouellette
Chlamydia is an obligate intracellular bacterium and, as such, has significantly reduced its genome size and content. Although recent advances have allowed for transformation of C. trachomatis with an exogenous plasmid, genetic manipulation of Chlamydia remains challenging. In particular, the ability to create conditional knockouts has not been developed. This is particularly important given the likelihood that most genes within the small genome of Chlamydia may be essential. Here, I describe the feasibility of using CRISPR interference (CRISPRi) based on the catalytically inactive Cas9 variant (dCas9) of Staphylococcus aureus to inducibly, and reversibly, repress gene expression in C...
2018: Frontiers in Cellular and Infection Microbiology
Santosh K Ghosh, Zhimin Feng, Hisashi Fujioka, Renate Lux, Thomas S McCormick, Aaron Weinberg
Human beta defensins (hBDs) are small cationic peptides, expressed in mucosal epithelia and important agents of innate immunity, act as antimicrobial and chemotactic agents at mucosal barriers. In this perspective, we present evidence supporting a novel strategy by which the oral bacterium Fusobacterium nucleatum induces hBDs and other antimicrobial peptides (AMPs) in normal human oral epithelial cells (HOECs) and thereby protects them from other microbial pathogens. The findings stress (1) the physiological importance of hBDs, (2) that this strategy may be a mechanism that contributes to homeostasis and health in body sites constantly challenged with bacteria and (3) that novel properties identified in commensal bacteria could, one day, be harnessed as new probiotic strategies to combat colonization of opportunistic pathogens...
2018: Frontiers in Microbiology
Julia Koehler Leman, Richard Bonneau, Martin B Ulmschneider
Modeling membrane protein (MP) folding, insertion, association and their interactions with other proteins, lipids, and drugs requires accurate transfer free energies (TFEs). Various TFE scales have been derived to quantify the energy required or released to insert an amino acid or protein into the membrane. Experimental measurement of TFEs is challenging, and only few scales were extended to depth-dependent energetic profiles. Statistical approaches can be used to derive such potentials; however, this requires a sufficient number of MP structures...
March 13, 2018: Scientific Reports
Amy N Jacobson, Biswa P Choudhury, Michael A Fischbach
Lipopolysaccharide (LPS), a cell-associated glycolipid that makes up the outer leaflet of the outer membrane of Gram-negative bacteria, is a canonical mediator of microbe-host interactions. The most prevalent Gram-negative gut bacterial taxon, Bacteroides , makes up around 50% of the cells in a typical Western gut; these cells harbor ~300 mg of LPS, making it one of the highest-abundance molecules in the intestine. As a starting point for understanding the biological function of Bacteroides LPS, we have identified genes in Bacteroides thetaiotaomicron VPI 5482 involved in the biosynthesis of its lipid A core and glycan, generated mutants that elaborate altered forms of LPS, and used matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry to interrogate the molecular features of these variants...
March 13, 2018: MBio
Paula M Tribelli, Nancy I López
It is well known that cold environments are predominant over the Earth and there are a great number of reports analyzing bacterial adaptations to cold. Most of these works are focused on characteristics traditionally involved in cold adaptation, such as the structural adjustment of enzymes, maintenance of membrane fluidity, expression of cold shock proteins and presence of compatible solutes. Recent works based mainly on novel "omic" technologies have presented evidence of the presence of other important features to thrive in cold...
March 13, 2018: Life
Taressa Bull, Amanda Corley, Danielle J Smyth, David J McMillan, Kimble R Dunster, John F Fraser
BACKGROUND: Extracorporeal membrane oxygenation (ECMO) delivers cardiac and/or respiratory support to critically ill patients who have failed conventional medical therapies. If the large-bore cannulas used to deliver ECMO become infected or dislodged, the patient consequences can be catastrophic. ECMO cannula-related infection has been reported to be double the rate of other vascular devices (7.1 vs 3.4 episodes/1000 ECMO days respectively). The aim of this study was to assess the ability of cyanoacrylate tissue adhesive (TA) to inhibit bacterial growth at the ECMO cannulation site, and the effectiveness of TA and securement devices in securing ECMO cannulas and tubing...
March 12, 2018: Intensive Care Medicine Experimental
Anne-Marie Garnerone, Fernando Sorroche, Lan Zou, Céline Mathieu-Demazière, Chang Fu Tian, Catherine Masson-Boivin, Jacques Batut
An ongoing signal exchange fine-tunes the symbiotic interaction between rhizobia and legumes, ensuring the establishment and maintenance of mutualism. In a recently identified regulatory loop, endosymbiotic S. meliloti exert a negative feedback on root infection in response to unknown plant cues. Upon signal perception, three bacterial Adenylate Cyclases (ACs) of the inner membrane, CyaD1, CyaD2 and CyaK, synthesize the second messenger cAMP that, together with the cAMP-dependent Clr transcriptional activator, activates the expression of genes involved in root infection control...
March 12, 2018: Journal of Bacteriology
Krishnan Raghunathan, Nora J Foegeding, Anne M Campbell, Timothy L Cover, Melanie D Ohi, Anne K Kenworthy
Helicobacter pylori , a Gram-negative bacterium, is a well-known risk factor for gastric cancer. H. pylori vacuolating cytotoxin A (VacA) is a secreted pore-forming toxin that induces a wide range of cellular responses. Like many other bacterial toxins, VacA has been hypothesized to utilize lipid rafts to gain entry into host cells. Here, we use Giant Plasma Membrane Vesicles (GPMVs) as a model system to understand the preferential partitioning of VacA into lipid rafts. We show that a wild-type toxin predominantly associates with the raft phase...
March 12, 2018: Infection and Immunity
Rakshak Kumar, Vishal Acharya, Srijana Mukhia, Dharam Singh, Sanjay Kumar
Pseudomonas frederiksbergensis ERDD5:01 is a psychrotrophic bacteria isolated from the glacial stream flowing from East Rathong glacier in Sikkim Himalaya. The strain showed survivability at high altitude stress conditions like freezing, frequent freeze-thaw cycles, and UV-C radiations. The complete genome of 5,746,824 bp circular chromosome and a plasmid of 371,027 bp was sequenced to understand the genetic basis of its survival strategy. Multiple copies of cold-associated genes encoding cold active chaperons, general stress response, osmotic stress, oxidative stress, membrane/cell wall alteration, carbon storage/starvation and, DNA repair mechanisms supported its survivability at extreme cold and radiations corroborating with the bacterial physiological findings...
March 9, 2018: Genomics
Paula A Santana, Nicolás Salinas, Claudio A Álvarez, Luis A Mercado, Fanny Guzmán
In this work, the potential antimicrobial role and mechanism of action of α-helix domain of trout and salmon IL-8 against Eschericia coli, Pseudomonas aeruginosa and Staphylococcus aureus was investigated. By an in silico analysis of the primary structure of IL-8 from Oncorhynchus mykiss and salmo salar, it was evidenced that γ-core motif was present, as in the vast majority of kinocidins. The α-helix domain of IL-8 (αIL-8) was synthesized by solid phase peptide synthesis and showed a tendency to form an α-helix conformation, as revealed by circular dichroism...
March 9, 2018: Biochemical and Biophysical Research Communications
Mizuki Sekiya, Yu Shimoyama, Taichi Ishikawa, Minoru Sasaki, Masamitsu Futai, Mayumi Nakanishi-Matsui
Porphyromonas gingivalis is a well-known Gram-negative bacterium that causes periodontal disease. The bacterium metabolizes amino acids and peptides to obtain energy. An ion gradient across its plasma membrane is thought to be essential for nutrient import. However, it is unclear whether an ion-pumping ATPase responsible for the gradient is required for bacterial growth. Here, we report the inhibitory effect of protonophores and inhibitors of a proton-pumping ATPase on the growth of P. gingivalis. Among the compounds examined, curcumin and citreoviridin appreciably reduced the bacterial growth...
March 9, 2018: Biochemical and Biophysical Research Communications
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