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https://www.readbyqxmd.com/read/28088639/docosahexaenoic-acid-loaded-lipid-nanoparticles-with-bactericidal-activity-against-helicobacter-pylori
#1
Catarina Leal Seabra, Cláudia Nunes, Maria Gomez-Lazaro, Marta Correia, José Carlos Machado, Inês C Gonçalves, Celso A Reis, Salette Reis, M Cristina L Martins
Docosahexaenoic acid (DHA), an omega-3 polyunsaturated fatty acid present in fish oil, has been described as a promising molecule to the treatment of Helicobacter pylori gastric infection. However, due to its highly unsaturated structure, DHA can be easily oxidized loosing part of its bioactivity. This work aims the nanoencapsulation of DHA to improve its bactericidal efficacy against H. pylori. DHA was loaded into nanostructured lipid carriers (NLC) produced by hot homogenization and ultrasonication using a blend of lipids (Precirol ATO5(®), Miglyol-812(®)) and a surfactant (Tween 60(®))...
January 11, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28088521/signal-peptidase-i-processed-secretory-signal-sequences-selection-for-and-against-specific-amino-acids-at-the-second-position-of-mature-protein
#2
Yaramah M Zalucki, Michael P Jennings
Signal peptides direct proteins from the cytoplasm to the periplasm. These N-terminal peptides are cleaved upon entry to the periplasm by either signal peptidase I, or signal peptidase II for lipoproteins. Signal peptidase I is a serine protease that has either a serine-lysine or serine-histidine catalytic dyad present in the active site. The recognition site for signal peptide cleavage by signal peptidase I has been defined primarily by an Ala-X-Ala motif at the C-terminal end of the signal peptide, one amino acid away from the cleavage site...
January 11, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28087802/cytochrome-c-peroxidase-ccp-is-a-molecular-determinant-of-the-oxidative-stress-response-in-the-extreme-acidophilic-leptospirillum-sp-cf-1
#3
C Zapata, B Paillavil, R Chávez, P Álamos, G Levicán
Bioleaching processes are used to recover metals from sulfidic ores. Biofilm formation on ores is important for bioleaching because the attached microorganisms start the leaching process by concentrating ferric ions in the extracellular matrix. It has been shown that hydrogen peroxide is spontaneously generated on the surface of ores and that it negatively influences the growth and activity of microorganisms. However, the mechanism by which bioleaching microorganisms tolerate exogenous H2O2 as an adaptive trait remains elusive...
January 12, 2017: FEMS Microbiology Ecology
https://www.readbyqxmd.com/read/28078625/analysis-of-an-n-terminal-deletion-in-subunit-a-of-the-escherichia-coli-atp-synthase
#4
Robert R Ishmukhametov, Jessica DeLeon-Rangel, Shaotong Zhu, Steven B Vik
Subunit a is a membrane-bound stator subunit of the ATP synthase and is essential for proton translocation. The N-terminus of subunit a in E. coli is localized to the periplasm, and contains a sequence motif that is conserved among some bacteria. Previous work has identified mutations in this region that impair enzyme activity. Here, an internal deletion was constructed in subunit a in which residues 6-20 were replaced by a single lysine residue, and this mutant was unable to grow on succinate minimal medium...
January 11, 2017: Journal of Bioenergetics and Biomembranes
https://www.readbyqxmd.com/read/28076802/peldor-spectroscopy-reveals-two-defined-states-of-a-sialic-acid-trap-transporter-sbp-in-solution
#5
Janin Glaenzer, Martin F Peter, Gavin H Thomas, Gregor Hagelueken
The tripartite ATP-independent periplasmic (TRAP) transporters are a widespread class of membrane transporters in bacteria and archaea. Typical substrates for TRAP transporters are organic acids including the sialic acid N-acetylneuraminic acid. The substrate binding proteins (SBP) of TRAP transporters are the best studied component and are responsible for initial high-affinity substrate binding. To better understand the dynamics of the ligand binding process, pulsed electron-electron double resonance (PELDOR, also known as DEER) spectroscopy was applied to study the conformational changes in the N-acetylneuraminic acid-specific SBP VcSiaP...
January 10, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28072820/p-cymene-promotes-its-catabolism-through-the-p-cymene-and-the-p-cumate-pathways-activates-a-stress-response-and-reduces-the-biofilm-formation-in-burkholderia-xenovorans-lb400
#6
Loreine Agulló, María José Romero-Silva, Mirian Domenech, Michael Seeger
p-Cymene is an aromatic terpene that is present in diverse plant species. The aims of this study were to study the p-cymene metabolism in the model aromatic-degrading bacterium Burkholderia xenovorans LB400, and its response to p-cymene. The catabolic p-cymene (cym) and p-cumate (cmt) genes are clustered on the LB400 major chromosome. B. xenovorans LB400 was able to grow on p-cymene as well as on p-cumate as a sole carbon and energy sources. LB400 growth attained higher cell concentration at stationary phase on p-cumate than on p-cymene...
2017: PloS One
https://www.readbyqxmd.com/read/28069820/comprehensive-spatial-analysis-of-the-borrelia-burgdorferi-lipoproteome-reveals-a-compartmentalization-bias-toward-the-bacterial-surface
#7
Alexander S Dowdell, Maxwell D Murphy, Christina Azodi, Selene K Swanson, Laurence Florens, Shiyong Chen, Wolfram R Zückert
: The Lyme disease spirochete Borrelia burgdorferi is unique among bacteria in its large number of lipoproteins that are encoded by a small, exceptionally fragmented and predominantly linear genome. Peripherally anchored in either the inner or outer membrane and facing either the periplasm or the external environment, these lipoproteins assume varied roles. A prominent subset functioning as the apparent linchpins of the enzootic tick-vertebrate infection cycle has been explored as vaccine targets...
January 9, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28067918/structural-insights-into-the-secretin-translocation-channel-in-the-type-ii-secretion-system
#8
Zhaofeng Yan, Meng Yin, Dandan Xu, Yongqun Zhu, Xueming Li
The secretin GspD of the type II secretion system (T2SS) forms a channel across the outer membrane in Gram-negative bacteria to transport substrates from the periplasm to the extracellular milieu. The lack of an atomic-resolution structure of the GspD channel hinders the investigation of substrate translocation mechanism of T2SS. Here we report cryo-EM structures of two GspD channels (∼1 MDa), from Escherichia coli K12 and Vibrio cholerae, at ∼3 Å resolution. The structures reveal a pentadecameric channel architecture, wherein three rings of GspD N domains form the periplasmic channel...
January 9, 2017: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/28065271/signal-peptidase-enzymology-and-substrate-specificity-profiling
#9
R E Dalbey, D Pei, Ö D Ekici
Signal peptidases are membrane proteases that play crucial roles in the protein transport pathway of bacteria. They cleave off the signal peptide from precursor proteins that are membrane inserted by the SecYEG or Tat translocons. Signal peptide cleavage releases the translocated protein from the inner membrane allowing the protein to be exported to the periplasm, outer membrane, or secreted into the medium. Signal peptidases are very important proteins to study. They are unique serine proteases with a Ser-Lys dyad, catalyze cleavage at the membrane surface, and are promising potential antibacterial drug targets...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28062839/redox-and-ph-linked-conformational-changes-in-triheme-cytochrome-ppca-from-geobacter-sulfurreducens
#10
Leonor Morgado, Marta Bruix, P Raj Pokkuluri, Carlos A Salgueiro, David L Turner
The periplasmic triheme cytochrome PpcA from Geobacter sulfurreducens is highly abundant; it is the likely reservoir of electrons to the outer surface to assist the reduction of extracellular terminal acceptors; these include insoluble metal oxides in natural habitats and electrode surfaces from which electricity can be harvested. A detailed thermodynamic characterization of PpcA showed that it has an important redox-Bohr effect that might implicate the protein in e(-)/H(+) coupling mechanisms to sustain cellular growth...
January 15, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28061385/an-efficient-perturbation-method-to-predict-the-functionally-key-sites-of-glutamine-binding-protein
#11
Dashuai Lv, Cunxin Wang, Chunhua Li, Jianjun Tan, Xiaoyi Zhang
Glutamine-Binding Protein (GlnBP) of Escherichia coli, an important member of the periplasmic binding protein family, is responsible for the first step in the active transport of glutamine across the cytoplasmic membrane. In this work, the functionally key regulation sites of GlnBP were identified by utilizing a perturbation method proposed by our group, in which the residues whose perturbations markedly change the binding free energy between GlnBP and glutamine are considered to be functionally key residues...
December 29, 2016: Computational Biology and Chemistry
https://www.readbyqxmd.com/read/28060819/an-anti-human-lutheran-glycoprotein-phage-antibody-inhibits-cell-migration-on-laminin-511-epitope-mapping-of-the-antibody
#12
Yurie Enomoto-Okawa, Yuka Maeda, Nozomi Harashima, Yumika Sugawara, Fumihiko Katagiri, Kentaro Hozumi, Kam Man Hui, Motoyoshi Nomizu, Yuji Ito, Yamato Kikkawa
The Lutheran glycoprotein (Lu), also known as basal cell adhesion molecule (B-CAM), is an Ig superfamily (IgSF) transmembrane receptor for laminin α5. Although Lu is not present in normal hepatocytes, its expression is significantly increased in hepatocellular carcinoma (HCC). In this study, we isolated thirteen phage antibodies to Lu from a phage library of peripheral blood from HCC patients, suggesting that these patients produced autoantibodies against endogenous Lu. To characterize the phage antibodies, we determined the Lu domains they recognize...
2017: PloS One
https://www.readbyqxmd.com/read/28059088/insights-into-the-mechanistic-basis-of-plasmid-mediated-colistin-resistance-from-crystal-structures-of-the-catalytic-domain-of-mcr-1
#13
Philip Hinchliffe, Qiu E Yang, Edward Portal, Tom Young, Hui Li, Catherine L Tooke, Maria J Carvalho, Neil G Paterson, Jürgen Brem, Pannika R Niumsup, Uttapoln Tansawai, Lei Lei, Mei Li, Zhangqi Shen, Yang Wang, Christopher J Schofield, Adrian J Mulholland, Jianzhong Shen, Natalie Fey, Timothy R Walsh, James Spencer
The polymixin colistin is a "last line" antibiotic against extensively-resistant Gram-negative bacteria. Recently, the mcr-1 gene was identified as a plasmid-mediated resistance mechanism in human and animal Enterobacteriaceae, with a wide geographical distribution and many producer strains resistant to multiple other antibiotics. mcr-1 encodes a membrane-bound enzyme catalysing phosphoethanolamine transfer onto bacterial lipid A. Here we present crystal structures revealing the MCR-1 periplasmic, catalytic domain to be a zinc metalloprotein with an alkaline phosphatase/sulphatase fold containing three disulphide bonds...
January 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28057704/mycobacterium-tuberculosis-protease-marp-activates-a-peptidoglycan-hydrolase-during-acid%C3%A2-stress
#14
Helene Botella, Julien Vaubourgeix, Myung Hee Lee, Naomi Song, Weizhen Xu, Hideki Makinoshima, Michael S Glickman, Sabine Ehrt
Mycobacterium tuberculosis (Mtb) can persist in the human host in a latent state for decades, in part because it has the ability to withstand numerous stresses imposed by host immunity. Prior studies have established the essentiality of the periplasmic protease MarP for Mtb to survive in acidified phagosomes and establish and maintain infection in mice. However, the proteolytic substrates of MarP that mediate these phenotypes were unknown. Here, we used biochemical methods coupled with supravital chemical probes that facilitate imaging of nascent peptidoglycan to demonstrate that during acid stress MarP cleaves the peptidoglycan hydrolase RipA, a process required for RipA's activation...
January 5, 2017: EMBO Journal
https://www.readbyqxmd.com/read/28040784/genetic-analysis-of-the-lambda-spanins-rz-and-rz1-identification-of-functional-domains
#15
Jesse Cahill, Manoj Rajaure, Chandler O'Leary, Jordan Sloan, Armando Marrufo, Ashley Holt, Aneesha Kulkarni, Oscar Hernandez, Ry Young
Coliphage lambda proteins Rz and Rz1 are the inner membrane and outer membrane subunits of the spanin complex, a heterotetramer that bridges the periplasm and is essential for the disruption of the outer membrane during phage lysis. Recent evidence suggests the spanin complex functions by fusing the inner and outer membrane. Here we use a genetics approach to investigate and characterize determinants of spanin function. Because Rz1 is entirely embedded in the +1 reading frame of Rz, the genes were dis-embedded before using random mutagenesis to construct a library of lysis-defective alleles for both genes...
December 30, 2016: G3: Genes—Genomes—Genetics
https://www.readbyqxmd.com/read/28036380/two-component-signaling-system-vgrrs-directly-senses-extracytoplasmic-and-intracellular-iron-to-control-bacterial-adaptation-under-iron-depleted-stress
#16
Li Wang, Yue Pan, Zhi-Hui Yuan, Huan Zhang, Bao-Yu Peng, Fang-Fang Wang, Wei Qian
Both iron starvation and excess are detrimental to cellular life, especially for animal and plant pathogens since they always live in iron-limited environments produced by host immune responses. However, how organisms sense and respond to iron is incompletely understood. Herein, we reveal that in the phytopathogenic bacterium Xanthomonas campestris pv. campestris, VgrS (also named ColS) is a membrane-bound receptor histidine kinase that senses extracytoplasmic iron limitation in the periplasm, while its cognate response regulator, VgrR (ColR), detects intracellular iron excess...
December 2016: PLoS Pathogens
https://www.readbyqxmd.com/read/28036244/viscosity-dependent-variations-in-the-cell-shape-and-swimming-manner-of-leptospira
#17
Kyosuke Takabe, Hajime Tahara, Md Shafiqul Islam, Samia Affroze, Seishi Kudo, Shuichi Nakamura
Spirochetes are spiral or flat-wave-shaped Gram-negative bacteria that have periplasmic flagella (PF) between the peptidoglycan layer and outer membrane. Rotation of the PF transforms the cell body shape periodically, allowing the cell to swim in aqueous environments. Because the virulence of motility-deficient mutants of pathogenic species is drastically attenuated, motility is thought to be an essential virulence factor in spirochetes. However, it remains unknown how motility practically contributes to the infection process...
December 30, 2016: Microbiology
https://www.readbyqxmd.com/read/28035602/proteomic-characterization-of-the-outer-membrane-vesicle-of-the-halophilic-marine-bacterium-novosphingobium-pentaromativorans-us6-1
#18
Sung Ho Yun, Sang-Yeop Lee, Chi-Won Choi, Hayoung Lee, Hyun-Joo Ro, Sangmi Jun, Yong Min Kwon, Kae Kyoung Kwon, Sang-Jin Kim, Gun-Hwa Kim, Seung Il Kim
Novosphingobium pentaromativorans US6-1 is a Gram-negative halophilic marine bacterium able to utilize several polycyclic aromatic hydrocarbons such as phenanthrene, pyrene, and benzo[a]pyrene. In this study, using transmission electron microscopy, we confirmed that N. pentaromativorans US6-1 produces outer membrane vesicles (OMVs). N. pentaromativorans OMVs (hereafter OMVNovo) are spherical in shape, and the average diameter of OMVNovo is 25-70 nm. Proteomic analysis revealed that outer membrane proteins and periplasmic proteins of N...
January 2017: Journal of Microbiology / the Microbiological Society of Korea
https://www.readbyqxmd.com/read/28028176/a-two-component-nox-like-system-in-bacteria-is-involved-in-the-electron-transfer-chain-to-the-methionine-sulfoxide-reductase-msrp
#19
Celine Juillan-Binard, Antoine Picciocchi, Jean-Pierre Andrieu, Jerome Dupuy, Isabelle Petit-Hartlein, Christelle Caux-Thang, Corinne Vivès, Vincent Nivière, Franck Fieschi
MsrPQ is a newly identified methionine sulfoxide reductase system found in bacteria, which appears to be specifically involved in the repair of periplasmic proteins oxidized by hypochlorous acid. It involves two proteins. A periplasmic one, MsrP previously named YedY, carrying out the Msr activity and MsrQ, an integral b-type heme membrane spanning protein, which acts as the specific electron donor to MsrP. MsrQ, previously named YedZ, was mainly characterized by bioinformatics as a member of the FRD superfamily of heme-containing membrane proteins, which include the NADPH oxidase proteins (NOX/DUOX)...
December 27, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28013221/biochemical-characterization-of-the-flagellar-stator-associated-inner-membrane-protein-flil-from-vibrio-alginolyticus
#20
Ananthanarayanan Kumar, Miyu Isumi, Mayuko Sakuma, Shiwei Zhu, Yuuki Nishino, Yasuhiro Onoue, Seiji Kojima, Yohei Miyanoiri, Katsumi Imada, Michio Homma
The flagellar motor is embedded in the cell envelope and rotates upon interaction between the stator and the rotor. The rotation is powered by ion flow through the stator. A single transmembrane protein named FliL is associated with torque generation in the flagellar motor. We established an Escherichia coli over-expression system for FliL of Vibrio alginolyticus, a marine bacterium that has a sodium-driven polar flagellum. We successfully expressed, purified, and crystallized the ca. 17 kDa full-length FliL protein and generated a construct that expresses only the ca...
December 24, 2016: Journal of Biochemistry
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