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Felipe Alves de Almeida, Natan de Jesus Pimentel Filho, Lanna Clícia Carrijo, Cláudia Braga Pereira Bento, Maria Cristina Baracat-Pereira, Uelinton Manoel Pinto, Leandro Licursi de Oliveira, Maria Cristina Dantas Vanetti
Quorum sensing (QS) is cell-cell communication mechanism mediated by signaling molecules known as autoinducers (AIs) that lead to differential gene expression. Salmonella is unable to synthesize the AI-1 acyl homoserine lactone (AHL), but is able to recognize AHLs produced by other microorganisms through SdiA protein. Our study aimed to evaluate the influence of AI-1 on the abundance of proteins and the levels of organic acids of Salmonella Enteritidis. The presence of N-dodecyl-homoserine lactone (C12-HSL) did not interfere on the growth or the total amount of extracted proteins of Salmonella...
December 1, 2016: Microbial Pathogenesis
Christine Olbjørn, Milada Cvancarova Småstuen, Espen Thiis-Evensen, Britt Nakstad, Morten Harald Vatn, Gøri Perminow
OBJECTIVE: To describe the prevalence of serological markers in newly diagnosed treatment-naïve pediatric inflammatory bowel disease (IBD), their utility in differentiating Crohn's disease (CD), ulcerative colitis (UC) and symptomatic non-IBD patients and whether serological markers are associated with early TNF blocker treatment. MATERIAL AND METHODS: Ninety-six children and adolescents <18 years, 58 with IBD and 38 symptomatic non-IBD controls were included...
November 25, 2016: Scandinavian Journal of Gastroenterology
Mahima Sharma, Aparna Dixit
Aeromonas hydrophila is one of the most virulent fish pathogens, causing colossal economic losses to the aquaculture industry annually. The absence of a safe and effective vaccine makes it very difficult to control this infection. Outer membrane proteins have been widely illustrated to confer protective immunity against a broad spectrum of gram negative bacteria. In the current study, we have analyzed the ability of B-cell epitopes of A. hydrophila's outer membrane protein C (OmpC) to confer protection against bacterial virulence...
December 7, 2016: Vaccine
Ria van Boxtel, Agnes A Wattel, Jesús Arenas, Wil H F Goessens, Jan Tommassen
Although AmpC β-lactamases can barely or not degrade carbapenems, they can sequester them and prevent them from reaching their targets. Thus, carbapenem resistance in Escherichia coli and other Enterobacteriaceae can result from production of AmpC and simultaneous reduction of antibiotic influx into the periplasm by mutations in the porin genes. Here, we investigated the route and genetic mechanisms of acquiring carbapenem resistance in a clinical E. coli isolate carrying blaCMY-2 on a plasmid by selecting for mutants that are resistant to increasing concentrations of meropenem...
October 31, 2016: Antimicrobial Agents and Chemotherapy
Kalle Kipper, Ebba Gregorsson Lundius, Vladimir Curic, Ivana Nikic, Edward A Lemke, Manfred Wiessler, Johan Elf
Small synthetic fluorophores are in many ways superior to fluorescent proteins as labels for imaging. A major challenge is to use them for a protein-specific labeling in living cells. Here, we report on our use of noncanonical amino acids that are genetically encoded via the pyrrolysyl-tRNA/pyrrolysyl-RNA synthetase pair at artificially introduced TAG codons in a recoded E. coli strain. The strain is lacking endogenous TAG codons and the TAG-specific release factor RF1. The amino acids contain bioorthogonal groups that can be clicked to externally supplied dyes, thus enabling protein-specific labeling in live cells...
October 24, 2016: ACS Synthetic Biology
Christina M Beck, Julia L E Willett, David A Cunningham, Jeff J Kim, David A Low, Christopher S Hayes
Many Gram-negative bacterial pathogens express contact-dependent growth inhibition (CDI) systems that promote cell-cell interaction. CDI+ bacteria express surface CdiA effector proteins, which transfer their C-terminal toxin domains into susceptible target cells upon binding to specific receptors. CDI+ cells also produce immunity proteins that neutralize the toxin domains delivered from neighboring siblings. Here, we show that CdiAEC536 from uropathogenic Escherichia coli 536 (EC536) uses OmpC and OmpF as receptors to recognize target bacteria...
October 2016: PLoS Pathogens
Luana G M Ferrara, Gregor D Wallat, Lucile Moynié, Naresh N Dhanasekar, Soumeya Aliouane, Silvia Acosta-Gutiérrez, Jean-Marie Pagès, Jean-Michel Bolla, Mathias Winterhalter, Matteo Ceccarelli, James H Naismith
The Gram-negative organism Campylobacter jejuni is the major cause of food poisoning. Unlike Escherichia coli, which has two major porins, OmpC and OmpF, C. jejuni has one, termed major outer membrane protein (MOMP) through which nutrients and antibiotics transit. We report the 2.1-Å crystal structure of C. jejuni MOMP expressed in E. coli and a lower resolution but otherwise identical structure purified directly from C. jejuni. The 2.1-Å resolution structure of recombinant MOMP showed that although the protein has timeric arrangement similar to OmpC, it is an 18-stranded, not 16-stranded, β-barrel...
September 30, 2016: Journal of Molecular Biology
Xiaoyan Li, Runzhou Ni
There are over 350 million chronic carriers of hepatitis B virus (HBV) in the world, of whom about a third eventually develop severe HBV-related complications. HBV contributes to liver cirrhosis and hepatocellular carcinoma development. Remarkable progress has been made in selective inhibition of HBV replication by nucleoside analogs. However, how to generate protective antibody of HBsAb in HBV-infected patients after HBV-DNA becomes negative still remains a challenge for scientists. In this study, we show that OmpC-HBsAg 'a' epitope chimeric protein vaccine can break HBV tolerance and induce protective immunity in HBV transgenic mice based on mimicking T cell-independent antigen to bypass T cells from the adaptive immune system...
November 2016: Viral Immunology
Etsuko Sugawara, Seiji Kojima, Hiroshi Nikaido
: Klebsiella pneumoniae, one of the most important nosocomial pathogens, is becoming a major problem in health care because of its resistance to multiple antibiotics, including cephalosporins of the latest generation and, more recently, even carbapenems. This is largely due to the spread of plasmid-encoded extended-spectrum β-lactamases. However, antimicrobial agents must first penetrate the outer membrane barrier in order to reach their targets, and hydrophilic and charged β-lactams presumably diffuse through the porin channels...
December 1, 2016: Journal of Bacteriology
Behzad Dehghani, Mohammad Mottamedifar, Hossein Khoshkharam-Roodmajani, Amir Hassanzadeh, Kamyar Zomorrodian, Amir Rahimi
BACKGROUND: Outer membrane proteins (OMPs) constitute the main structure and about half of the cell wall of Gram-negative bacteria. The OMPs of Escherichia coli (E. coli) play an important role in its drug resistance. Previous studies have shown that the OMPs of E. coli enhance its pathogenic effects by helping the bacterium to evade the immune defense and promote its adsorption to host cells. We sought to compare E. coli isolates collected from different hospital wards and to perform a primary investigation of the association between the serotypes and profiles of their OMPs...
September 2016: Iranian Journal of Medical Sciences
Anna M Stenkova, Evgeniya P Bystritskaya, Konstantin V Guzev, Alexander V Rakin, Marina P Isaeva
The genus Yersinia includes species with a wide range of eukaryotic hosts (from fish, insects, and plants to mammals and humans). One of the major outer membrane proteins, the porin OmpC, is preferentially expressed in the host gut, where osmotic pressure, temperature, and the concentrations of nutrients and toxic products are relatively high. We consider here the molecular evolution and phylogeny of Yersinia ompC. The maximum likelihood gene tree reflects the macroevolution processes occurring within the genus Yersinia...
2016: Evolutionary Bioinformatics Online
Joris van der Heijden, Lisa A Reynolds, Wanyin Deng, Allan Mills, Roland Scholz, Koshi Imami, Leonard J Foster, Franck Duong, B Brett Finlay
UNLABELLED: The outer membrane (OM) of Gram-negative bacteria provides protection against toxic molecules, including reactive oxygen species (ROS). Decreased OM permeability can promote bacterial survival under harsh circumstances and protects against antibiotics. To better understand the regulation of OM permeability, we studied the real-time influx of hydrogen peroxide in Salmonella bacteria and discovered two novel mechanisms by which they rapidly control OM permeability. We found that pores in two major OM proteins, OmpA and OmpC, could be rapidly opened or closed when oxidative stress is encountered and that the underlying mechanisms rely on the formation of disulfide bonds in the periplasmic domain of OmpA and TrxA, respectively...
2016: MBio
M Alphan Aksoyoglu, Rudolf Podgornik, Sergey M Bezrukov, Philip A Gurnev, Murugappan Muthukumar, V Adrian Parsegian
Nonideal polymer mixtures of PEGs of different molecular weights partition differently into nanosize protein channels. Here, we assess the validity of the recently proposed theoretical approach of forced partitioning for three structurally different β-barrel channels: voltage-dependent anion channel from outer mitochondrial membrane VDAC, bacterial porin OmpC (outer membrane protein C), and bacterial channel-forming toxin α-hemolysin. Our interpretation is based on the idea that relatively less-penetrating polymers push the more easily penetrating ones into nanosize channels in excess of their bath concentration...
August 9, 2016: Proceedings of the National Academy of Sciences of the United States of America
Anaïs Brosse, Anna Korobeinikova, Susan Gottesman, Maude Guillier
Two-component systems (TCS) and small regulatory RNAs (sRNAs) are both widespread regulators of gene expression in bacteria. TCS are in most cases transcriptional regulators. A large class of sRNAs act as post-transcriptional regulators of gene expression that modulate the translation and/or stability of target-mRNAs. Many connections have been recently unraveled between these two types of regulators, resulting in mixed regulatory circuits with poorly characterized properties. This study focuses on the negative feedback circuit that exists between the EnvZ-OmpR TCS and the OmrA/B sRNAs...
November 16, 2016: Nucleic Acids Research
Shuai Zhi, Qiaozhi Li, Yutaka Yasui, Graham Banting, Thomas A Edge, Edward Topp, Tim A McAllister, Norman F Neumann
Several studies have demonstrated that E. coli appears to display some level of host adaptation and specificity. Recent studies in our laboratory support these findings as determined by logic regression modeling of single nucleotide polymorphisms (SNP) in intergenic regions (ITGRs). We sought to determine the degree of host-specific information encoded in various ITGRs across a library of animal E. coli isolates using both whole genome analysis and a targeted ITGR sequencing approach. Our findings demonstrated that ITGRs across the genome encode various degrees of host-specific information...
October 2016: Molecular Phylogenetics and Evolution
Fuguo Liu, Xiaoqian Tang, Xiuzhen Sheng, Jing Xing, Wenbin Zhan
Outer membrane protein C of Edwardsiella tarda is a major cell surface antigen and it was identified to be an immunogenic protein by Western blot using flounder (Paralichthys olivaceus) anti-recombinant OmpC (rOmpC), and anti-E. tarda antibodies. rOmpC tested the immune protective effect against E. tarda challenge in a flounder model and produced a relative percentage of survival rate of 85%. The immune response of flounder induced by rOmpC was investigated, and the results showed that: (1) the levels of specific serum antibodies induced by rOmpC were significantly higher than the control group after the second week after immunization, and the peak level occurred at week five after immunization; (2) rOmpC could induce the proliferation of sIg+ lymphocytes, and the peak levels of sIg+ lymphocytes in blood, spleen, and pronephros occurred at 4-5 weeks after immunization; and (3) the MHCIIα, CD4-1, IL-1β, IL-6 and TNF-α genes were significantly induced after being injected with rOmpC...
2016: International Journal of Molecular Sciences
Jia Du, Bin Li, Jianming Cao, Qing Wu, Huale Chen, Yuanbo Hou, En Zhang, Tieli Zhou
The emergence and dissemination of NDM-1 (New Delhi metallo-β-lactamase-1)-producing Enterobacteriaceae have resulted in a worldwide public health risk. This study described a high incidence and endemic spread of NDM-1-producing extensively drug-resistant Escherichia coli in a teaching hospital in Zhejiang province, China. We recovered six nonduplicated NDM-1-producing E. coli isolates from May 2014 to August 2014 with positive modified Hodge test and EDTA synergistic test. These isolates were highly resistant to β-lactam antimicrobials, aminoglycosides, and quinolones...
July 6, 2016: Microbial Drug Resistance: MDR: Mechanisms, Epidemiology, and Disease
Wanchana Ungphakorn, Thomas Tängdén, Linus Sandegren, Elisabet I Nielsen
OBJECTIVES: Resistant subpopulations with reduced expression of outer membrane porins have been observed in ESBL-producing Escherichia coli during exposure to ertapenem. The aim of this work was to develop a pharmacokinetic-pharmacodynamic (PKPD) model to characterize the emergence of resistant E. coli during exposure to ertapenem and to predict bacterial killing following different dosing regimens of ertapenem. METHODS: Data from in vitro time-kill experiments were used to develop a mechanism-based PKPD model for three E...
September 2016: Journal of Antimicrobial Chemotherapy
Sunita Kumari Yadav, Jitendra Kumar Meena, Mahima Sharma, Aparna Dixit
Aeromonas hydrophila is a gram-negative fish pathogenic bacterium, also responsible for causing opportunistic pathological conditions in humans. It causes a number of diseases in fish due to which the fish industry incurs huge economic losses annually. Due to problems of antibiotic resistance, and the rapidity with which the infection spreads among fishes, vaccination remains the most effective strategy to combat this infection in fish populations. Among various virulence factors associated with bacterial virulence, outer membrane proteins have been widely evaluated for their vaccine potential owing to their surface exposure and related role in pathogenicity...
August 2016: Immunologic Research
Mariano Andrea Scorciapino, Tommaso D'Agostino, Silvia Acosta-Gutierrez, Giuliano Malloci, Igor Bodrenko, Matteo Ceccarelli
BACKGROUND: In Gram-negative bacteria, the outer-membrane represents an additional barrier for antibiotics to permeate inside pathogens. Our inability to come up with novel effective antibiotics mostly relies upon insufficient understanding of the molecular basis behind outer-membrane penetration. RESULTS: Polar antibiotics can permeate through water-filled porins, such as OmpF and OmpC from Escherichia coli. Through molecular modeling, permeation of imipenem and meropenem was found to be strongly dependent upon capability of drugs to properly align their electric dipole to the internal electric field in the restricted region of the pore...
June 2016: Future Medicinal Chemistry
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