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Ishan Ghai, Harsha Bajaj, Jayesh Arun Bafna, Hussein Ali El Damrany Hussein, Mathias Winterhalter, Richard Wagner
The outer cell wall of the Gram-negative bacteria is a crucial barrier for antibiotics to reach their target. Here we show that the chemical stability of the widely used antibiotic ampicillin is a major factor in the permeation across OmpF to reach the target in the periplasm. Using planar lipid bilayer we investigated the interactions and permeation of OmpF with ampicillin, its basic pH induced primary degradation product (penicilloic acid), and the chemically more stable benzylpenicillin. We found that the solute induced ion current fluctuation is 10 times higher with penicilloic-acid than with ampicillin...
March 14, 2018: Journal of Biological Chemistry
Dan-Feng Zhang, Jin-Zhou Ye, Hong-Hou Dai, Xiang-Min Lin, Hui Li, Xuan-Xian Peng
Ethanol is an efficient disinfectant, but long-term and wide usage of ethanol leads to microbial tolerance. Bacteria with the tolerance are widely identified. However, mechanisms of the tolerance are not elucidated. To explore the mechanisms of outer membrane (OM) proteins underlying ethanol tolerance in bacteria, functional proteomic methodologies were utilized to characterize OM proteins of E. coli suddenly exposed to 3.125% ethanol. Of eleven proteins altered significantly, seven were OM proteins, in which LamB, FadL and OmpC were up-regulated, and OmpT, OmpF, Tsx and OmpA were down-regulated...
March 5, 2018: Journal of Proteomics
Xiangna Zhao, Yujun Cui, Yanfeng Yan, Zongmin Du, Yafang Tan, Huiying Yang, Yujing Bi, Pingping Zhang, Lei Zhou, Dongsheng Zhou, Yanping Han, Yajun Song, Xiaoyi Wang, Ruifu Yang
No abstract text is available yet for this article.
March 15, 2018: Journal of Virology
Kyung Min Choi, Mi Hyun Kim, Hua Cai, Yong Jin Lee, Yeongjin Hong, Phil Youl Ryu
Salmonella enterica serovar Typhimurium is one of the most important bacterial pathogens causing diarrhea. The resistance of S. typhimurium to antimicrobial agents, which has recently been isolated from patients, is causing serious problems. We investigated the effects of salicylic acid (Sal) and acetyl salicylate (AcSal) on the susceptibility of S. typhimurium to cephalosporin antibiotics, which are known to increase resistance to cephalosporin and quinolone antibiotics. The MIC of cephalosporin antibiotics was higher than that of the media without Sal...
January 2018: Chonnam Medical Journal
Yafei Ye, Lijuan Xu, Yanping Han, Zhe Chen, Cailin Liu, Liang Ming
Carbapenemase-producing 'super bacteria', particularly NDM-1 and its variants, have become a major public health concern worldwide. The present study aimed to explore the molecular mechanism for carbapenem resistance of clinical Enterobacteriaceae isolates. Seventy-eight non-repeated Enterobacteriaceae strains resistant to any carbapenem were screened at the First Affiliated Hospital of Zhengzhou University (Zhengzhou, China) between December 2011 and December 2015. Outer membrane porin (OMP) proteins were detected using SDS-PAGE...
January 2018: Experimental and Therapeutic Medicine
Maximilien Lopes-Rodrigues, Jordi Triguero, Juan Torras, Eric A Perpète, Catherine Michaux, David Zanuy, Carlos Alemán
Outer-membrane porins are currently being used to prepare bioinspired nanomembranes for selective ion transport by immobilizing them into polymeric matrices. However, the fabrication of these protein-integrated devices has been found to be strongly influenced by the instability of the β-barrel porin structure, which depends on surrounding environment. In this work, molecular dynamics simulations have been used to investigate the structural stability of a representative porin, OmpF, in three different environments: (i) aqueous solution at pH=7; (ii) a solution of neutral detergent in a concentration similar to the critical micelle concentration; and (iii) the protein embedded into a neutral detergent bilayer...
January 2, 2018: Biophysical Chemistry
Shaoying Wang, Zhengyi Zhao, Farzin Haque, Peixuan Guo
Biological systems contain highly-ordered structures performing diverse functions. The elegant structures of biomachines have inspired the development of nanopores as single molecule sensors. Over the years, the utility of nanopores for detecting a wide variety of analytes have rapidly emerged for sensing, sequencing and diagnostic applications. Several protein channels with diverse shapes and sizes, such as motor channels from bacteriophage Phi29, SPP1, T3, and T4, as well as α-hemolysin, MspA, aerolysin, FluA, OmpF/G, CsgG, ClyA, have been continually investigated and developed as nanopores...
December 9, 2017: Current Opinion in Biotechnology
E V Sidorin, V A Khomenko, N Yu Kim, P S Dmitrenok, A M Stenkova, O D Novikova, T F Solov'eva
Recombinant porin OmpF (an integral protein of bacterial outer membrane) from Yersinia pseudotuberculosis was synthesized in Escherichia coli cells as inclusion bodies. By combining the methods of anion-exchange and gel filtration chromatographies, recombinant OmpF (rOmpF) was isolated as an individual protein in its denatured state, and its characteristic properties (molecular mass, N-terminal amino acid sequence, and hydrodynamic radius of the protein in 8 M urea solution) were determined. According to the data of gel filtration, dynamic light scattering, optical spectroscopy, and binding of the hydrophobic fluorescent probe 8-anilino-1-naphthalenesulfonic acid, the rOmpF is fully unfolded in 8 M urea and exists in random coil conformation...
November 2017: Biochemistry. Biokhimii︠a︡
Sushovan Dam, Jean-Marie Pagès, Muriel Masi
Antibiotic resistant Gram-negative bacteria are a serious threat for public health. The permeation of antibiotics through their outer membrane is largely dependent on porin, changes in which cause reduced drug uptake and efficacy. Escherichia coli produces two major porins, OmpF and OmpC. MicF and MicC are small non-coding RNAs (sRNAs) that modulate the expression of OmpF and OmpC, respectively. In this work, we investigated factors that lead to increased production of MicC. micC promoter region was fused to lacZ , and the reporter plasmid was transformed into E...
December 6, 2017: Antibiotics
Kwang Soo Shin, Sung Kuk Lee
Transposon mutagenesis was used to identify three mutants of E. coli that exhibited increased free fatty acid (FFA) production, which resulted from the disruption of genes related to membrane transport. Deletion of envR, gusC, and mdlA individually in a recombinant E. coli strain resulted in 1.4-, 1.8-, and 1.2-fold increases in total FFA production, respectively. In particular, deletion of envR increased the percentage of extracellular FFA to 46%, compared with 29% for the control strain. Multiple deletion of envR, gusC, mdlA, ompF, and fadL had a synergistic effect on FFA production, resulting in high extracellular FFA production, comprising up to 50% of total FFA production...
December 27, 2017: Journal of Agricultural and Food Chemistry
Huilin Ma, Aliza Khan, Shikha Nangia
The self-assembly of outer membrane protein F (OmpF) in the outer membrane of Escherichia coli Gram-negative bacteria was studied using multiscale molecular dynamics simulations. To facilitate the long timescale required for protein assembly, coarse-grained parameterization of E. coli outer membrane lipids was first developed. The OmpF monomers formed stable dimers at specific protein-protein interactions sites irrespective of the lipid membrane environment. The dimer intermediate was asymmetric but provided a template to form a symmetric trimer...
November 22, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Ina Meuskens, Marcin Michalik, Nandini Chauhan, Dirk Linke, Jack C Leo
Almost all integral membrane proteins found in the outer membranes of Gram-negative bacteria belong to the transmembrane β-barrel family. These proteins are not only important for nutrient uptake and homeostasis, but are also involved in such processes as adhesion, protein secretion, biofilm formation, and virulence. As surface exposed molecules, outer membrane β-barrel proteins are also potential drug and vaccine targets. High production levels of heterologously expressed proteins are desirable for biochemical and especially structural studies, but over-expression and subsequent purification of membrane proteins, including outer membrane proteins, can be challenging...
2017: Frontiers in Cellular and Infection Microbiology
Jannik Nedergaard Pedersen, Jan Skov Pedersen, Daniel E Otzen
Proteins and lipids can form complexes called liprotides, in which the partially denatured protein forms a shell encasing a lipid core. This effectively stabilizes a lipid micelle in an aqueous solvent and suggests that liprotides may provide a suitable vessel for membrane proteins. Accordingly we have investigated if liprotides consisting of α-lactalbumin and oleate could aid folding of four different outer membrane proteins (OMPs) tOmpA, PagP, BamA and OmpF. tOmpA was able to fold in the presence of the liprotide, and folding did not occur if only oleate or α-lactalbumin were added...
November 1, 2017: Protein Science: a Publication of the Protein Society
Olga Portnyagina, Elena Zelepuga, Valentina Khomenko, Elena Solov'eva, Tamara Solov'eva, Olga Novikova
This work is devoted to the ascertainment of serological cross-reactivity between OmpF porin from Yersinia pseudotuberculosis (YpOmpF) and human thyroid-stimulating hormone receptor (hTSHR). Extracts containing hTSHR were isolated from surgical thyroid tissue of patients with clinical and diagnostic signs of diffuse toxic goiter. Monoclonal antibodies to hTSHR (mAbs) were shown to interact both with antigens in thyroid tissue extracts and with YpOmpF. Models of spatial structures of trimer and monomer complexes of YpOmpF with antibodies to hTSHR were also constructed...
October 24, 2017: International Journal of Biological Macromolecules
Dexian Zhang, Zehui Zhang, Chengcheng Huang, Xiang Gao, Zhuang Wang, Yaochuan Liu, Chunlian Tian, Wei Hong, Shengli Niu, Mingchun Liu
Bovine mastitis is still a central problem on dairy farms despite control programs, and Escherichia coli is a crucial pathogen during the development of bovine mastitis. The virulence genes, antimicrobial susceptibility, and mortality of mice infected with different E. coli isolates from bovine mastitis were determined in this study. According to the presence of the specific genes chuA, yjaA, and TspE4.C2, these isolates mainly belonged to 2 different groups: group A (47/79) and group B1 (22/79). The ompC gene was detected in all the isolates, followed by fimH (89...
October 18, 2017: Journal of Dairy Science
Christopher L Johnson, Alexandra S Solovyova, Olli Hecht, Colin Macdonald, Helen Waller, J Günter Grossmann, Geoffrey R Moore, Jeremy H Lakey
Intrinsically disordered regions within proteins are critical elements in many biomolecular interactions and signaling pathways. Antibacterial toxins of the colicin family, which could provide new antibiotic functions against resistant bacteria, contain disordered N-terminal translocation domains (T-domains) that are essential for receptor binding and the penetration of the Escherichia coli outer membrane. Here we investigate the conformational behavior of the T-domain of colicin N (ColN-T) to understand why such domains are widespread in toxins that target Gram-negative bacteria...
October 17, 2017: Biophysical Journal
Javier Abellón-Ruiz, Shreyas S Kaptan, Arnaud Baslé, Beatrice Claudi, Dirk Bumann, Ulrich Kleinekathöfer, Bert van den Berg
The Gram-negative bacterial outer membrane (OM) is a unique bilayer that forms an efficient permeation barrier to protect the cell from noxious compounds1 , 2 . The defining characteristic of the OM is lipid asymmetry, with phospholipids comprising the inner leaflet and lipopolysaccharides comprising the outer leaflet1-3 . This asymmetry is maintained by the Mla pathway, a six-component system that is widespread in Gram-negative bacteria and is thought to mediate retrograde transport of misplaced phospholipids from the outer leaflet of the OM to the cytoplasmic membrane4 ...
December 2017: Nature Microbiology
Lucio Manzi, Andrew S Barrow, Jonathan T S Hopper, Renata Kaminska, Colin Kleanthous, Carol V Robinson, John E Moses, Neil J Oldham
Mapping the interaction sites between membrane-spanning proteins is a key challenge in structural biology. In this study a carbene-footprinting approach was developed and applied to identify the interfacial sites of a trimeric, integral membrane protein, OmpF, solubilised in micelles. The diazirine-based footprinting probe is effectively sequestered by, and incorporated into, the micelles, thus leading to efficient labelling of the membrane-spanning regions of the protein upon irradiation at 349 nm. Areas associated with protein-protein interactions between the trimer subunits remained unlabelled, thus revealing their location...
September 27, 2017: Angewandte Chemie
Kaushik Bhattacharjee, Shakti Kumar, Narasinga Rao Palepu, Pradeep Kumar Patra, Kollipara Mohan Rao, Santa Ram Joshi
On screening of endolithic actinobacteria from a granite rock sample of Meghalaya for antibacterial compound, a novel antibacterial compound CCp1 was isolated from the fermentation broth of Actinomadura sp. AL2. On purification of the compound based on chromatographic techniques followed by characterization with FT-IR, UV-visible, (1)H NMR, (13)C NMR and mass spectrometry, the molecular formula of the compound was generated as C20H17N3O2, a furopyrimidine derivative. In vitro antibacterial activity of the compound was evaluated against both Gram positive and negative bacteria by agar well diffusion assay...
September 20, 2017: World Journal of Microbiology & Biotechnology
Antonio Alcaraz, M Lidón López, María Queralt-Martín, Vicente M Aguilella
Synthetic nanopores and mesoscopic protein channels have common traits like the importance of electrostatic interactions between the permeating ions and the nanochannel. Ion transport at the nanoscale occurs under confinement conditions so that the usual assumptions made in microfluidics are challenged, among others, by interfacial effects such as access resistance (AR). Here, we show that a sound interpretation of electrophysiological measurements in terms of channel ion selective properties requires the consideration of interfacial effects, up to the point that they dominate protein channel conductance in diluted solutions...
October 24, 2017: ACS Nano
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