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https://www.readbyqxmd.com/read/28231453/siderophore-transport-by-mmpl5-mmps5-protein-complex-in-mycobacterium-tuberculosis
#1
Padmani Sandhu, Yusuf Akhter
Iron is an essential metal ion required for the various physiological activities of bacteria. The pathogenic bacteria remain dependent on the host cell for their iron requirements and evolved with specialized scavenging machinery in the form of iron chelating siderophores. Mycobacterium tuberculosis has two types of siderophore molecules, mycobactin and carboxymycobactin. These are synthesized inside bacterial cells and need to be transported outside by specialized membrane associated proteins. MmpL5-MmpS5 (mycobacterial membrane protein large5-mycobacterial membrane protein small5) complex has been linked to the export of non-ferrated siderophores to extracellular environment but the precise molecular mechanism involved was largely unknown...
February 14, 2017: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/28231283/rapid-evolution-of-distinct-helicobacter-pylori-subpopulations-in-the-americas
#2
Kaisa Thorell, Koji Yahara, Elvire Berthenet, Daniel J Lawson, Jane Mikhail, Ikuko Kato, Alfonso Mendez, Cosmeri Rizzato, María Mercedes Bravo, Rumiko Suzuki, Yoshio Yamaoka, Javier Torres, Samuel K Sheppard, Daniel Falush
For the last 500 years, the Americas have been a melting pot both for genetically diverse humans and for the pathogenic and commensal organisms associated with them. One such organism is the stomach-dwelling bacterium Helicobacter pylori, which is highly prevalent in Latin America where it is a major current public health challenge because of its strong association with gastric cancer. By analyzing the genome sequence of H. pylori isolated in North, Central and South America, we found evidence for admixture between H...
February 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28231167/antibacterial-activity-of-fructus-forsythia-essential-oil-and-the-application-of-eo-loaded-nanoparticles-to-food-borne-pathogens
#3
Na Guo, Qing-Yan Gai, Jiao Jiao, Wei Wang, Yuan-Gang Zu, Yu-Jie Fu
Fructus forsythia essential oil (FEO) with excellent antibacterial activity was rarely reported. The objective of the present study was to investigate the antibacterial activity and the antibacterial mechanism of FEO against two food-borne pathogenic bacteria, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in vitro. When treated FEO, the zones of inhibition (ZOI) of E. coli (20.5 ± 0.25 mm) and S. aureus (24.3 ± 0.21 mm) were much larger than control (p < 0.05). The minimum inhibitory concentrations (MICs) of FEO were 3...
October 29, 2016: Foods (Basel, Switzerland)
https://www.readbyqxmd.com/read/28230992/novel-design-of-heptad-amphiphiles-to-enhance-cell-selectivity-salt-resistance-anti-biofilm-properties-and-their-membrane-disruptive-mechanism
#4
Xiujing Dou, Xin Zhu, Jiajun Wang, Na Dong, Anshan Shan
Coiled-coil, a basic folding pattern of native proteins, was previously demonstrated to be associated with the specific spatial recognition, association, and dissociation of proteins and can be used to perfect engineering peptide model. Thus, in this study, a series of amphiphiles composed of heptads repeats with coiled-coil structures was constructed, and the designed peptides exhibited a broad spectrum of antimicrobial activities. Circular dichroism and biological assays showed that the heptad repeats and length of the linker between the heptads largely influenced the amphiphile's helical propensity and cell selectivity...
February 23, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28230084/highly-potent-antimicrobial-peptides-from-n-terminal-membrane-binding-region-of-e-coli-mreb
#5
Karabi Saikia, Yalavarthi Durga Sravani, Vibin Ramakrishnan, Nitin Chaudhary
Microbial pathogenesis is a serious health concern. The threat escalates as the existing conventional antimicrobials are losing their efficacy against the evolving pathogens. Peptides hold promise to be developed into next-generation antibiotics. Antimicrobial peptides adopt amphipathic structures that could selectively bind to and disrupt the microbial membranes. Interaction of proteins with membranes is central to all living systems and we reasoned that the membrane-binding domains in microbial proteins could be developed into efficient antimicrobials...
February 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28230048/differential-regulation-of-the-epr3-receptor-coordinates-membrane-restricted-rhizobial-colonization-of-root-nodule-primordia
#6
Yasuyuki Kawaharada, Mette W Nielsen, Simon Kelly, Euan K James, Kasper R Andersen, Sheena R Rasmussen, Winnie Füchtbauer, Lene H Madsen, Anne B Heckmann, Simona Radutoiu, Jens Stougaard
In Lotus japonicus, a LysM receptor kinase, EPR3, distinguishes compatible and incompatible rhizobial exopolysaccharides at the epidermis. However, the role of this recognition system in bacterial colonization of the root interior is unknown. Here we show that EPR3 advances the intracellular infection mechanism that mediates infection thread invasion of the root cortex and nodule primordia. At the cellular level, Epr3 expression delineates progression of infection threads into nodule primordia and cortical infection thread formation is impaired in epr3 mutants...
February 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/28229332/the-role-of-riboflavin-in-decolourisation-of-congo-red-and-bioelectricity-production-using-shewanella-oneidensis-mr1-under-mfc-and-non-mfc-conditions
#7
Ola M Gomaa, Segun Fapetu, Godfrey Kyazze, Tajalli Keshavarz
Dissimilatory metal reducing bacteria can exchange electrons extracellularly and hold great promise for their use in simultaneous wastewater treatment and electricity production. This study investigated the role of riboflavin, an electron carrier, in the decolourisation of Congo red in microbial fuel cells (MFCs) using Shewanella oneidensis MR-1 as a model organism. The contribution of the membrane-bound protein MtrC to the decolourisation process was also investigated. Within the range of riboflavin concentrations tested, 20 µM was found to be the best with >95% of the dye (initial concentration 200 mg/L) decolourised in MFCs within 50 h compared to 90% in the case where no riboflavin was added...
March 2017: World Journal of Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28228554/association-of-lyn-kinase-with-membrane-rafts-determines-its-negative-influence-on-lps-induced-signaling
#8
Kinga Borzęcka-Solarz, Justyna Dembińska, Aneta Hromada-Judycka, Gabriela Traczyk, Anna Ciesielska, Ewelina Ziemlińska, Anna Świątkowska, Katarzyna Kwiatkowska
Lipopolysaccharide (LPS) is the component of Gram-negative bacteria which activates Toll-like receptor 4 (TLR4) to trigger pro-inflammatory responses. We examined the involvement of Lyn tyrosine kinase in TLR4 signaling of macrophages, distinguishing its catalytic activity and intermolecular interactions. For this, a series of Lyn-GFP constructs bearing point mutations in particular domains of Lyn were overexpressed in RAW264 macrophage-like cells or murine peritoneal macrophages, and their influence on LPS-induced responses was analyzed...
February 22, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28228236/inhibition-of-an-enriched-culture-of-ammonia-oxidizing-bacteria-by-two-different-nanoparticles-silver-and-magnetite
#9
Camila Michels, Simone Perazzoli, Hugo M Soares
Metal and metal oxide nanoparticles are getting attention over the past years. They can be used to several purposes, especially in commercial and medical applications. Undoubtedly, this lead to higher production and, consequently, increasing the risks of exposition, once they can be released into environment without a proper control. However, their impact over the bacteria present in wastewater treatment plants (WWTP), manly over nitrifying bacteria, which are the most susceptible to toxic compounds, are still not very well established...
February 19, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28226897/effect-of-growth-solution-membrane-size-and-array-connection-on-microbial-fuel-cell-power-supply-for-medical-devices
#10
Daniel N Roxby, Nham Tran, Pak-Lam Yu, Hung T Nguyen, Daniel N Roxby, Nham Tran, Pak-Lam Yu, Hung T Nguyen, Pak-Lam Yu, Hung T Nguyen, Daniel N Roxby, Nham Tran
Implanted biomedical devices typically last a number of years before their batteries are depleted and a surgery is required to replace them. A Microbial Fuel Cell (MFC) is a device which by using bacteria, directly breaks down sugars to generate electricity. Conceptually there is potential to continually power implanted medical devices for the lifetime of a patient. To investigate the practical potential of this technology, H-Cell Dual Chamber MFCs were evaluated with two different growth solutions and measurements recorded for maximum power output both of individual MFCs and connected MFCs...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226206/exploration-of-the-innate-immune-system-of-styela-clava-zn-2-binding-enhances-the-antimicrobial-activity-of-the-tunicate-peptide-clavanin-a
#11
Samuel A Juliano, Scott Pierce, James A DeMayo, Marcy J Balunas, Alfredo M Angeles-Boza
Tunicates have been used as primitive models for understanding cell mediated and humoral immunity. Clavanin A (ClavA) is a potent antimicrobial peptide produced by the solitary tunicate Styela clava. In this work, we demonstrate that ClavA utilizes Zn(2+) ions to potentiate its antimicrobial activity. A reduced concentration at which the peptide inhibits the growth of bacteria and an increase in the rate of killing is observed in the presence of Zn(2+). Membrane depolarization, β-galactosidase leakage and potassium leakage assays indicate that ClavA is membrane active, forms small pores, but induces cell death by targeting an intracellular component...
February 22, 2017: Biochemistry
https://www.readbyqxmd.com/read/28225803/bacterial-expression-correct-membrane-targeting-and-functional-folding-of-the-hiv-1-membrane-protein-vpu-using-a-periplasmic-signal-peptide
#12
Arpan Deb, William A Johnson, Alexander P Kline, Boston J Scott, Lydia R Meador, Dustin Srinivas, Jose M Martin-Garcia, Katerina Dörner, Chad R Borges, Rajeev Misra, Brenda G Hogue, Petra Fromme, Tsafrir S Mor
Viral protein U (Vpu) is a type-III integral membrane protein encoded by Human Immunodeficiency Virus-1 (HIV- 1). It is expressed in infected host cells and plays several roles in viral progeny escape from infected cells, including down-regulation of CD4 receptors. But key structure/function questions remain regarding the mechanisms by which the Vpu protein contributes to HIV-1 pathogenesis. Here we describe expression of Vpu in bacteria, its purification and characterization. We report the successful expression of PelB-Vpu in Escherichia coli using the leader peptide pectate lyase B (PelB) from Erwinia carotovora...
2017: PloS One
https://www.readbyqxmd.com/read/28224999/allograft-inflammatory-factor-1-is-a-regulator-of-transcytosis-in-m-cells
#13
Sari Kishikawa, Shintaro Sato, Satoshi Kaneto, Shigeo Uchino, Shinichi Kohsaka, Seiji Nakamura, Hiroshi Kiyono
M cells in follicle-associated epithelium (FAE) are specialized antigen-sampling cells that take up intestinal luminal antigens. Transcription factor Spi-B regulates M-cell maturation, but the molecules that promote transcytosis within M cells are not fully identified. Here we show that mouse allograft inflammatory factor 1 (Aif1) is expressed by M cells and contributes to M-cell transcytosis. FAE in Aif1(-/-) mice has suppressed uptake of particles and commensal bacteria, compared with wild-type mice. Translocation of Yersinia enterocolitica, but not of Salmonella enterica serovar Typhimurium, leading to the generation of antigen-specific IgA antibodies, is also diminished in Aif1-deficient mice...
February 22, 2017: Nature Communications
https://www.readbyqxmd.com/read/28224490/predicting-beta-barrel-transmembrane-proteins-using-hmms
#14
Georgios N Tsaousis, Stavros J Hamodrakas, Pantelis G Bagos
Transmembrane beta-barrels (TMBBs) constitute an important structural class of membrane proteins located in the outer membrane of gram-negative bacteria, and in the outer membrane of chloroplasts and mitochondria. They are involved in a wide variety of cellular functions and the prediction of their transmembrane topology, as well as their discrimination in newly sequenced genomes is of great importance as they are promising targets for antimicrobial drugs and vaccines. Several methods have been applied for the prediction of the transmembrane segments and the topology of beta barrel transmembrane proteins utilizing different algorithmic techniques...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28223520/membrane-integration-of-an-essential-%C3%AE-barrel-protein-prerequires-burial-of-an-extracellular-loop
#15
Joseph S Wzorek, James Lee, David Tomasek, Christine L Hagan, Daniel E Kahne
The Bam complex assembles β-barrel proteins into the outer membrane (OM) of Gram-negative bacteria. These proteins comprise cylindrical β-sheets with long extracellular loops and create pores to allow passage of nutrients and waste products across the membrane. Despite their functional importance, several questions remain about how these proteins are assembled into the OM after their synthesis in the cytoplasm and secretion across the inner membrane. To understand this process better, we studied the assembly of an essential β-barrel substrate for the Bam complex, BamA...
February 21, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28223511/a-signal-sequence-suppressor-mutant-that-stabilizes-an-assembled-state-of-the-twin-arginine-translocase
#16
Qi Huang, Felicity Alcock, Holger Kneuper, Justin C Deme, Sarah E Rollauer, Susan M Lea, Ben C Berks, Tracy Palmer
The twin-arginine protein translocation (Tat) system mediates transport of folded proteins across the cytoplasmic membrane of bacteria and the thylakoid membrane of chloroplasts. The Tat system of Escherichia coli is made up of TatA, TatB, and TatC components. TatBC comprise the substrate receptor complex, and active Tat translocases are formed by the substrate-induced association of TatA oligomers with this receptor. Proteins are targeted to TatBC by signal peptides containing an essential pair of arginine residues...
February 21, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28223456/a-natural-chimeric-pseudomonas-bacteriocin-with-novel-pore-forming-activity-parasitizes-the-ferrichrome-transporter
#17
Maarten G K Ghequire, Lieselore Kemland, Ernesto Anoz-Carbonell, Susan K Buchanan, René De Mot
Modular bacteriocins represent a major group of secreted protein toxins with a narrow spectrum of activity, involved in interference competition between Gram-negative bacteria. These antibacterial proteins include a domain for binding to the target cell and a toxin module at the carboxy terminus. Self-inhibition of producers is provided by coexpression of linked immunity genes that transiently inhibit the toxin's activity through formation of bacteriocin-immunity complexes or by insertion in the inner membrane, depending on the type of toxin module...
February 21, 2017: MBio
https://www.readbyqxmd.com/read/28223392/streptococcus-mitis-and-s-oralis-lack-a-requirement-for-cdsa-the-enzyme-required-for-synthesis-of-major-membrane-phospholipids-in-bacteria
#18
Hannah M Adams, Luke R Joyce, Ziqiang Guan, Ronda L Akins, Kelli L Palmer
Synthesis and integrity of the cytoplasmic membrane is fundamental to cellular life. Experimental evolution studies have hinted at unique physiology in the Gram-positive bacteria Streptococcus mitis and S. oralis These organisms commonly cause bacteremia and infectious endocarditis (IE) but are rarely investigated in mechanistic studies of physiology and evolution. Unlike other Gram-positive pathogens, high-level (MIC ≥ 256 μg/mL) daptomycin resistance rapidly emerges in S. mitis and S. oralis after a single drug exposure...
February 21, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28223348/immunoactive-clostridial-membrane-vesicle-production-is-regulated-by-a-sporulation-factor
#19
Nozomu Obana, Ryoma Nakao, Kyoko Nagayama, Kouji Nakamura, Hidenobu Senpuku, Nobuhiko Nomura
Recently, many Gram-positive bacteria as well as gram-negative bacteria have been reported to produce MVs, but little is known regarding the regulators involved in MV formation. We found that a Gram-positive anaerobic pathogen, Clostridium perfringens, produces MVs predominantly containing membrane proteins and cell wall components. These MVs stimulated pro-inflammatory cytokine production in mouse macrophage-like cells. We suggested that MVs induced IL-6 production through the TLR2 signaling pathway. Thus, the MV could have a role in the bacteria-host interaction and bacterial infection pathogenesis...
February 21, 2017: Infection and Immunity
https://www.readbyqxmd.com/read/28223313/active-multi-enzyme-assemblies-for-long-chain-olefinic-hydrocarbon-biosynthesis
#20
James K Christenson, Matthew R Jensen, Brandon R Goblirsch, Fatuma Mohamed, Wei Zhang, Carrie M Wilmot, Lawrence P Wackett
Bacteria from different Phyla produce long-chain olefinic hydrocarbons derived from an OleA-catalyzed Claisen condensation of two fatty acyl-CoA substrates, followed by reduction and oxygen elimination reactions catalyzed by the proteins OleB, OleC, and OleD. In this report, OleA, OleB, OleC, and OleD were individually purified as soluble proteins, and all were found to be essential for reconstituting hydrocarbon biosynthesis. Recombinant co-expression of tagged OleABCD proteins from Xanthomonas campestris in Escherichia coli and purification over His6x- and FLAG-columns resulted in OleA separating whilst OleBCD purified together, irrespective of which of the four Ole proteins were tagged...
February 21, 2017: Journal of Bacteriology
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