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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...
September 23, 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-coded extended spectrum β-lactamases. However, antimicrobial agents must first penetrate through the outer membrane barrier in order to reach their targets, and hydrophilic and charged β-lactams presumably diffuse through the porin channels...
September 19, 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...
July 20, 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
Ayaka Washizaki, Tetsuro Yonesaki, Yuichi Otsuka
Bacteriophages have strict host specificity and the step of adsorption is one of key factors for determining host specificity. Here, we systematically examined the interaction between the Escherichia coli receptors lipopolysaccharide (LPS) and outer membrane protein C (OmpC), and the long tail fibers of bacteriophage T4. Using a variety of LPS mutants, we demonstrated that T4 has no specificity for the sugar sequence of the outer core (one of three LPS regions) in the presence of OmpC but, in the absence of OmpC, can adsorb to a specific LPS which has only one or two glucose residues without a branch...
June 6, 2016: MicrobiologyOpen
H Sasimali M Soysa, Wipa Suginta
Chitoporin from the chitinolytic marine Vibrio has been characterized as a trimeric OmpC-like channel responsible for effective chitin uptake. In this study we describe the identification and characterization of a novel OprD-like chitoporin (so-called EcChiP) from Escherichia coli The gene was identified, cloned, and functionally expressed in the Omp-deficient E. coli BL21 (Omp8) Rosetta strain. On size exclusion chromatography, EcChiP had an apparent native molecular mass of 50 kDa, as predicted by amino acid sequencing and mass analysis, confirming that the protein is a monomer...
June 24, 2016: Journal of Biological Chemistry
Hui Huang, Yawei Sun, Li Yuan, Yushan Pan, Yanlin Gao, Caihui Ma, Gongzheng Hu
The two-component signal transduction system CpxAR is especially widespread in Gram-negative bacteria. It has been reported that CpxAR contributes to the multidrug resistance (MDR) in Escherichia coli. CpxR is a response regulator in the two-component CpxAR system. The aim of this study was to explore the role of cpxR in the MDR of S. enterica serovar Typhimurium. The minimal inhibitory concentrations (MICs) of various antibiotics commonly used in veterinary medicine for strains JS (a multidrug-susceptible standard strain of S...
2016: Frontiers in Microbiology
Mariane Rezende Dias, Valéria Quintana Cavicchioli, Anderson Carlos Camargo, Frederico Germano Piscitelli Alvarenga Lanna, Paulo Sérgio de Arruda Pinto, Luciano Dos Santos Bersot, Luís Augusto Nero
Due to the importance of Salmonella spp. in poultry products, this study aimed to track its main contamination routes since slaughtering reception to processing of chicken end cuts. Samples from different steps of slaughtering and processing (n = 277) were collected from two chicken slaughterhouses (Sl1 and Sl2) located in Minas Gerais state, Brazil, and subjected to Salmonella spp. detection. The obtained isolates were subjected to serological identification and tested by PCR for specific Salmonella spp...
February 2016: Journal of Food Science and Technology
Annika Heininger, Rahmi Yusuf, Robert J Lawrence, Roger R Draheim
The Escherichia coli sensor kinase EnvZ modulates porin expression in response to various stimuli, including extracellular osmolarity, the presence of procaine and interaction with an accessory protein, MzrA. Two major outer membrane porins, OmpF and OmpC, act as passive diffusion-limited pores that allow compounds, including certain classes of antibiotics such as β-lactams and fluoroquinolones, to enter the bacterial cell. Even though the mechanisms by which EnvZ detects and processes the presence of various stimuli are a fundamental component of microbial physiology, they are not yet fully understood...
August 2016: Biochimica et Biophysica Acta
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