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https://www.readbyqxmd.com/read/29677599/bactericidal-activity-and-mechanisms-of-biobr-agbr-under-both-dark-and-visible-light-irradiation-conditions
#1
Ting Feng, Jialiang Liang, Zhiyao Ma, Mian Li, Meiping Tong
BiOBr-AgBr hybrid photocatalysts were synthesized via a facile precipitation and in-situ ion exchange method at room temperature. The as-synthesized photocatalysts were well characterized with different techniques. The disinfection activities of BiOBr-AgBr towards model bacterial strain Gram-negative Escherichia coli (E. coli) were tested under both dark and visible light irradiation conditions. 1 × 107 CFU/mL of E. coli cells could be completely inactivated by BiOBr-AgBr with the optimal silver amount (BiOBr-0...
April 8, 2018: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/29677594/mechanisms-of-oxidative-stress-caused-by-cuo-nanoparticles-to-membranes-of-the-bacterium-streptomyces-coelicolor-m145
#2
Xiaomei Liu, Jingchun Tang, Lan Wang, John P Giesy
Toxic effects of widely used CuO nanoparticles (NPs) on the genus Streptomyces has been seldom studied. This work investigated toxicities of several sizes of CuO nanoparticles (NPs) to Streptomyces coelicolor M145 (S. coelicolor M145). Compared with NPs, toxicity of micrometer-sized CuO on M145 was trivial. In 0.9% NaCl, when the concentration of CuO NPs was 100 mg/L, survival of bacteria increased from 18.3% in 20 nm particles to 31.1% in 100 nm particles. With increasing concentrations of CuO, the level of ROS gradually increased and there were significant differences (p < 0...
April 17, 2018: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/29675800/secretion-expression-of-human-neutrophil-peptide-1-hnp1-in-pichia-pastoris-and-its-functional-analysis-against-antibiotic-resistant-helicobacter-pylori
#3
Xiaolin Zhang, Anmin Jiang, Banghua Qi, Hao Yu, Youyi Xiong, Guoliang Zhou, Meisong Qin, Jinfeng Dou, Jianfei Wang
Human neutrophil peptide 1 (HNP1) is a small (3.44 kDa) cationic peptide that is a distinct member of the defensin family. HNP1 plays a crucial role in controlling bacterial infections, particularly by antibiotic-resistant bacteria, through membrane perforation patterns. The structural characteristics of HNP1's three intramolecular disulfide bridges cause difficulty in its synthesis via chemical methods. In this study, bioactive recombinant HNP1 was produced using the Pichia pastoris (P. Pichia) expression system...
April 19, 2018: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/29675399/sialidase-deficiency-in-porphyromonas-gingivalis-increases-il-12-secretion-in-stimulated-macrophages-through-regulation-of-cr3-incrna-gas5-and-mir-21
#4
Xue Yang, Yaping Pan, Xiaoyu Xu, Tong Tong, Shiwen Yu, Yue Zhao, Li Lin, Jingbo Liu, Dongmei Zhang, Chen Li
Porphyromonas gingivalis ( P. gingivalis ) is a major periodontal pathogen that can induce an immune response leading to a destructive inflammatory process. During the inflammatory process, interleukin-12 (IL-12) is secreted, correlating with bacterial clearance by macrophages. Bacterial sialidase has recently been shown to influence the synthesis and modification of the macromolecules on its surface, and is associated with the interaction between bacteria and host cells. We have previously constructed a P...
2018: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/29673980/photoactivated-2-3-distyrylindoles-kill-multi-drug-resistant-bacteria
#5
Leslie Edwards, Danielle Turner, Cody Champion, Megha Khandelwal, Kailee Zingler, Cassidy Stone, Ruwini D Rajapaksha, Jing Yang, Mahinda I Ranasinghe, Alexander Kornienko, Liliya V Frolova, Snezna Rogelj
Compounds based on the 2,3-distyrylindole scaffold were found to exhibit bactericidal properties upon irradiation with white light. At the concentration of 1 μM, the lead compound 1 completely (ca. 109  CFU/mL) eradicated such Gram-positive organisms as S. aureus (MRSA, MSSA), E. faecalis (VRE), S. pyogenes and S. mutans when irradiated with white light for 2 min. At the concentration of 5 μM and in the presence of polymyxin E at non-bactericidal 1.25 μg/mL concentration, 1 also showed a 7-log to 9-log reductions in bacterial counts of such Gram-negative organisms as multi-drug resistant (MDR) A...
April 3, 2018: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/29672978/disruption-of-the-e-coli-lptc-dimerization-interface-and-characterization-of-lipopolysaccharide-and-lpta-binding-to-monomeric-lptc
#6
Kathryn M Schultz, Matthew A Fischer, Elizabeth L Noey, Candice S Klug
Lipopolysaccharide (LPS) is an essential element of nearly all Gram-negative bacterial outer membranes and serves to protect the cell from adverse environmental stresses. Seven members of the lipopolysaccharide transport (Lpt) protein family function together to transport LPS from the inner membrane (IM) to the outer leaflet of the outer membrane of bacteria such as Escherichia coli. Each of these proteins has a solved crystal structure, including LptC, which is a largely periplasmic protein that is associated with the IM LptB2 FG complex and anchored to the membrane by an N-terminal helix...
April 19, 2018: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/29672023/chitosan-based-peptidopolysaccharides-as-cationic-antimicrobial-agents-and-antibacterial-coatings
#7
Dicky Pranantyo, Li Qun Xu, En-Tang Kang, Mary B Chan-Park
The rapid spread of multidrug resistant bacteria has called for effective antimicrobial agents which work on a more direct mechanism of killing. Cationic peptidopolysaccharides are developed in the present work to mimic the peptidoglycan structure of bacteria and to enhance the membrane-compromising bactericidal efficacy. Antimicrobial CysHHC10 peptide was grafted to the C-2 (amino) or C-6 (hydroxyl) position of chitosan backbone via thiol-maleimide 'click' conjugation, utilizing the maleimidohexanoic linkers...
April 19, 2018: Biomacromolecules
https://www.readbyqxmd.com/read/29671805/improving-the-activity-of-trp-rich-antimicrobial-peptides-by-arg-lys-substitutions-and-changing-the-length-of-cationic-residues
#8
Mauricio Arias, Kathlyn B Piga, M Eric Hyndman, Hans J Vogel
Antimicrobial peptides (AMPs) constitute a promising alternative for the development of new antibiotics that could potentially counteract the growing number of antibiotic-resistant bacteria. However, the AMP structure⁻function relationships remain unclear and detailed studies are still necessary. The positively charged amino acid residues (Arg and Lys) play a crucial role in the activity of most AMPs due to the promotion of electrostatic interactions between the peptides and bacterial membranes. In this work we have analyzed the antimicrobial and structural properties of several Trp-rich AMPs containing exclusively either Arg or Lys as the positively charged residues...
April 19, 2018: Biomolecules
https://www.readbyqxmd.com/read/29671790/chemical-synthesis-and-functional-analysis-of-varva-cyclotide
#9
Claudio A Álvarez, Paula A Santana, Omar Luna, Constanza Cárdenas, Fernando Albericio, María S Romero, Fanny Guzmán
Cyclotides are circular peptides found in various plant families. A cyclized backbone, together with multiple disulfide bonds, confers the peptides’ exceptional stability against protease digestion and thermal denaturation. In addition, the features of these antimicrobial molecules make them suitable for use in animal farming, such as aquaculture. Fmoc solid phase peptide synthesis on 2-chlorotrityl chlorine (CTC) resin using the “tea-bag” approach was conducted to generate the VarvA cyclotide identified previously from Viola arvensis ...
April 19, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/29671618/novel-naphthalimide-nitroimidazoles-as-multitargeting-antibacterial-agents-against-resistant-acinetobacter-baumannii
#10
Jie Kang, Lavanya Gopala, Vijai Kumar Reddy Tangadanchu, Wei-Wei Gao, Cheng-He Zhou
AIM: The increasing emergence of resistant bacteria imposed an urgent request to discover novel antibacterial agents. This work was to develop naphthalimide nitroimidazoles as potentially antibacterial agents. Results/methodology: Compound 9e showed the strong antibacterial activity (minimal inhibitory concentration = 0.013 μmol/ml) against resistant Acinetobacter baumannii (A. baumannii) with rapid killing effect and no obvious triggering of the development of resistance. Its combination use with chloromycin, norfloxacin or clinafloxacin improved the antibacterial potency...
April 19, 2018: Future Medicinal Chemistry
https://www.readbyqxmd.com/read/29669541/three-dimensional-models-of-mycobacterium-tuberculosis-proteins-rv1555-rv1554-and-their-docking-analyses-with-sildenafil-tadalafil-vardenafil-drugs-suggest-interference-with-quinol-binding-likely-to-affect-protein-s-function
#11
Pallabini Dash, M Bala Divya, Lalitha Guruprasad, Kunchur Guruprasad
BACKGROUND: Earlier based on bioinformatics analyses, we had predicted the Mycobacterium tuberculosis (M.tb) proteins; Rv1555 and Rv1554, among the potential new tuberculosis drug targets. According to the 'TB-drugome' the Rv1555 protein is 'druggable' with sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra) drugs. In the present work, we intended to understand via computer modeling studies, how the above drugs are likely to inhibit the M.tb protein's function. RESULTS: The three-dimensional computer models for M...
April 18, 2018: BMC Structural Biology
https://www.readbyqxmd.com/read/29666229/drought-delays-development-of-the-sorghum-root-microbiome-and-enriches-for-monoderm-bacteria
#12
Ling Xu, Dan Naylor, Zhaobin Dong, Tuesday Simmons, Grady Pierroz, Kim K Hixson, Young-Mo Kim, Erika M Zink, Kristin M Engbrecht, Yi Wang, Cheng Gao, Stephanie DeGraaf, Mary A Madera, Julie A Sievert, Joy Hollingsworth, Devon Birdseye, Henrik V Scheller, Robert Hutmacher, Jeffery Dahlberg, Christer Jansson, John W Taylor, Peggy G Lemaux, Devin Coleman-Derr
Drought stress is a major obstacle to crop productivity, and the severity and frequency of drought are expected to increase in the coming century. Certain root-associated bacteria have been shown to mitigate the negative effects of drought stress on plant growth, and manipulation of the crop microbiome is an emerging strategy for overcoming drought stress in agricultural systems, yet the effect of drought on the development of the root microbiome is poorly understood. Through 16S rRNA amplicon and metatranscriptome sequencing, as well as root metabolomics, we demonstrate that drought delays the development of the early sorghum root microbiome and causes increased abundance and activity of monoderm bacteria, which lack an outer cell membrane and contain thick cell walls...
April 16, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29663932/studies-on-the-antibacterial-activity-and-mechanism-of-antimicrobial-peptides-against-drug-resistant-bacteria
#13
Xiaofang Luo, Yanjun Liu, Zuodong Qin, Zhiyuan Jin, Liting Xu, Yang Liu, Linyan Cao, Fulin He, Xiaohong Gu, Xiaoping Ouyang
Antibiotic resistance is a growing threat to human health. More than anything else, multidrug-resistant gram-negative bacteria pose the biggest challenge to healthcare, which is predominantly due to the lack of effective therapeutic options. In the present study, we investigated the activities of peptides HX-12A, HX-12B and HX-12C against MDRAB and MDRKP isolates in vitro. Those three peptides displayed high antibacterial activities and rapid bactericidal effects against MDRAB and MDRKP isolates. Additionally, the peptides retained their activity even being present in pH 6...
March 1, 2018: Journal of Biomedical Nanotechnology
https://www.readbyqxmd.com/read/29662839/the-saposin-like-protein-apld-displays-pore-forming-activity-and-participates-in-defense-against-bacterial-infection-during-a-multicellular-stage-of-dictyostelium-discoideum
#14
Ranjani Dhakshinamoorthy, Moritz Bitzhenner, Pierre Cosson, Thierry Soldati, Matthias Leippe
Due to their archaic life style and microbivor behavior, amoebae may represent a source of antimicrobial peptides and proteins. The amoebic protozoon Dictyostelium discoideum has been a model organism in cell biology for decades and has recently also been used for research on host-pathogen interactions and the evolution of innate immunity. In the genome of D. discoideum , genes can be identified that potentially allow the synthesis of a variety of antimicrobial proteins. However, at the protein level only very few antimicrobial proteins have been characterized that may interact directly with bacteria and help in fighting infection of D...
2018: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/29662477/new-genes-involved-in-mild-stress-response-identified-by-transposon-mutagenesis-in-lactobacillus-paracasei
#15
Aurore Palud, Hélène Scornec, Jean-François Cavin, Hélène Licandro
Lactic acid bacteria (LAB) are associated with various plant, animal, and human niches and are also present in many fermented foods and beverages. Thus, they are subjected to several stress conditions and have developed advanced response mechanisms to resist, adapt, and grow. This work aimed to identify the genes involved in some stress adaptation mechanisms in LAB. For this purpose, global reverse genetics was applied by screening a library of 1287 Lactobacillus paracasei transposon mutants for mild monofactorial stresses...
2018: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29661863/-vibrio-cholerae-outer-membrane-vesicles-inhibit-bacteriophage-infection
#16
Tamara Reyes-Robles, Rebecca S Dillard, Lynne S Cairns, Cecilia A Silva-Valenzuela, Max Housman, Afsar Ali, Elizabeth R Wright, Andrew Camilli
Novel preventatives could help in efforts to limit Vibrio cholerae infection and the spread of cholera. Bacteriophage (or phage) treatment has been proposed to be an alternative intervention, given the rapid replication of virulent phages, prey specificity, and relative ease of finding new virulent phages. Phage tropism is dictated in part by the presence of phage receptors on the bacterial surface. While many phages that can kill V. cholerae have been isolated, whether this pathogen is able to defend itself by neutralizing phage binding is unknown...
April 16, 2018: Journal of Bacteriology
https://www.readbyqxmd.com/read/29661861/forespore-targeting-of-spovd-in-bacillus-subtilis-is-mediated-by-the-n-terminal-part-of-the-protein
#17
Margareth Sidarta, Dongdong Li, Lars Hederstedt, Ewa Bukowska-Faniband
SpoVD and PBP4b are structurally very similar high molecular weight, class B, penicillin-binding proteins produced early during sporulation in Bacillus subtilis SpoVD is known to be essential for endospore cortex synthesis and thereby production of heat-resistant spores. The role of PBP4b is still enigmatic. Both proteins are synthesized in the cytoplasm of the mother cell. PBP4b remains in the cytoplasmic membrane of the mother cell whereas SpoVD accumulates in the forespore outer membrane. By the use of SpoVD/PBP4b chimeras with swapped protein domains we show that the N-terminal part of SpoVD, containing the single transmembrane region, determines forespore targeting of the protein...
April 16, 2018: Journal of Bacteriology
https://www.readbyqxmd.com/read/29661272/hexameric-and-pentameric-complexes-of-the-exbbd-energizer-in-the-ton-system
#18
Saori Maki-Yonekura, Rei Matsuoka, Yoshiki Yamashita, Hirofumi Shimizu, Maiko Tanaka, Fumie Iwabuki, Koji Yonekura
Gram-negative bacteria import essential nutrients such as iron and vitamin B12 through outer membrane receptors. This process utilizes proton motive force harvested by the Ton system made up of three inner membrane proteins, ExbB, ExbD and TonB. ExbB and ExbD form the proton channel that energizes uptake through TonB. Recently, crystal structures suggest that the ExbB pentamer is the scaffold. Here, we present structures of hexameric complexes of ExbB and ExbD revealed by X-ray crystallography and single particle cryo-EM...
April 17, 2018: ELife
https://www.readbyqxmd.com/read/29661138/a-coxiella-burnetii-phospholipase-a-homolog-plda-is-required-for-optimal-growth-in-macrophages-and-developmental-form-lipid-remodeling
#19
Christopher M Stead, Diane C Cockrell, Paul A Beare, Heather E Miller, Robert A Heinzen
BACKGROUND: Many gram-negative bacteria produce an outer membrane phospholipase A (PldA) that plays an important role in outer membrane function and is associated with virulence. RESULTS: In the current study, we characterized a pldA mutant of Coxiella burnetii, an intracellular gram-negative pathogen and the agent of human Q fever. The C. burnetti pldA open reading frame directs synthesis of a protein with conserved PldA active site residues. A C. burnetii ΔpldA deletion mutant had a significant growth defect in THP-1 macrophages, but not axenic medium, that was rescued by complementation...
April 16, 2018: BMC Microbiology
https://www.readbyqxmd.com/read/29660310/a-modeling-and-simulation-perspective-on-the-mechanism-and-function-of-respiratory-complex-i
#20
REVIEW
Outi Haapanen, Vivek Sharma
Respiratory complex I is a giant redox-driven proton pump, and central to energy production in mitochondria and bacteria. It catalyses the reduction of quinone to quinol, and converts the free energy released into the endergonic proton translocation across the membrane. The proton pumping sets up the proton electrochemical gradient, which propels the synthesis of ATP. Despite the availability of extensive biochemical, biophysical and structural data on complex I, the mechanism of coupling between the electron and proton transfer reactions remain uncertain...
April 13, 2018: Biochimica et Biophysica Acta
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