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Journal articles on the topic 'Porin Porin'

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Published: 4 June 2021

Last updated: 5 February 2022

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1

Doménech-Sánchez, Antonio, Santiago Hernández-Allés, Luis Martínez-Martínez, Vicente J. Benedí та Sebastián Albertí. "Identification and Characterization of a New Porin Gene of Klebsiella pneumoniae: Its Role in β-Lactam Antibiotic Resistance". Journal of Bacteriology 181, № 9 (1999): 2726–32. http://dx.doi.org/10.1128/jb.181.9.2726-2732.1999.

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ABSTRACT Klebsiella pneumoniae porin genes were analyzed to detect mutations accounting for the porin deficiency observed in many β-lactam-resistant strains. PCR and Southern blot analysis revealed the existence of a third porin gene in addition to the OmpK36 and OmpK35 porin genes previously described. This new porin gene was designated ompK37 and is present in all of the clinical isolates tested. The OmpK37 porin gene was cloned, sequenced, and overexpressed in Escherichia coli. In contrast to that of the major porins, OmpK37 porin expression was only detectable by Western blot analysis in p

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2

Hernández-Allés, Santiago, Sebastián Albertí, Xavier Rubires, Susana Merino, Juan M. Tomás, and Vicente J. Benedí. "Isolation of FC3-11, a bacteriophage specific for theKlebsiella pneumoniaeporin OmpK36, and its use for the isolation of porin-deficient mutants." Canadian Journal of Microbiology 41, no. 4-5 (1995): 399–406. http://dx.doi.org/10.1139/m95-053.

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FC3-11, a bacteriophage specific for the Klebsiella pneumoniae porin OmpK36, was isolated by its ability to infect Escherichia coli strains expressing the cloned OmpK36 porin. Porin OmpK36 was shown to be the receptor for phage FC3-11 by the observations that K. pneumoniae and E. coli strains that do not express OmpK36 were resistant to phage FC3-11, the purified porin inactivated the phage, and mutants selected for FC3-11 resistance had lost OmpK36. The outer membrane protein OmpK35 was isolated from a K. pneumoniae phage-resistant mutant by using porin isolation methods and was shown to cont

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3

Hutsul, Joanne, Elizabeth Worobec, Tom R. Parr Jr., and Gerald W. Becker. "Comparative analyses of Serratia spp. outer membrane porin proteins." Canadian Journal of Microbiology 39, no. 4 (1993): 442–47. http://dx.doi.org/10.1139/m93-064.

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Eight Serratia strains and several members of the Enterobacteriaceae family were used in immunoblot and Southern DNA hybridization experiments and probed with antibody and DNA probes specific for the 41-kDa Serratia marcescens porin, to determine the extent of homology between Gram-negative porins. Immunoblot analyses performed using porin-specific rabbit sera and cell envelope preparations from these strains revealed that all strains produced at least one cross-reactive protein in the 41-kDa molecular weight range. Chromosomal DNA from each of the same strains was used in Southern analyses, p

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4

Jap, Bing K. "Structure of PhoE Porin as Determined by Electron Crystallography." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (1990): 92–93. http://dx.doi.org/10.1017/s042482010017921x.

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PhoE porin is a member of a family of pore forming proteins that are found in the outer membrane o Gram-negative bacteria. In E. coli , there are a variety of porins, such as OmpF, OmpC and PhoE. These porins have been shown to have no specific binding site for substrate although PhoE porin has been demonstrated to have some selectivity for anions and phosphate-containing compounds. Porins font general diffusion channels allowing small molecules, such as nutrients and waste products, of less that about 600 daltons, to diffuse freely across the membrane. In addition, porins also act as receptor

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5

Danilchanka, Olga, Mikhail Pavlenok, and Michael Niederweis. "Role of Porins for Uptake of Antibiotics by Mycobacterium smegmatis." Antimicrobial Agents and Chemotherapy 52, no. 9 (2008): 3127–34. http://dx.doi.org/10.1128/aac.00239-08.

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ABSTRACT The outer membrane of mycobacteria presents an effective permeability barrier for many antibiotics. Transport pathways across this membrane are unknown for most drugs. Here, we examined which antibiotics utilize the porin pathway across the outer membrane of the model organism Mycobacterium smegmatis. Deletion of the porins MspA and MspC drastically increased the resistance of M. smegmatis ML10 to β-lactam antibiotics, while its β-lactamase activity remained unchanged. These results are consistent with the ninefold-reduced outer membrane permeability of the M. smegmatis porin mutants

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6

Bay, Denice C., Joe D. O’Neil, and Deborah A. Court. "The influence of sterols on the conformation of recombinant mitochondrial porin in detergent." Biochemistry and Cell Biology 86, no. 6 (2008): 539–45. http://dx.doi.org/10.1139/o08-132.

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Mitochondrial porins (voltage-dependent anion-selective channels, VDAC) are key contributors to cellular metabolism. When isolated from mitochondria porins copurify with sterols, and some isolated forms of the protein require sterol for insertion into artificial membranes. Nonetheless, the contributions of sterols to the folded state of mitochondrial porin are not understood. Recently, with the goal of high-resolution structural studies, several laboratories have developed methods for folding recombinant porins at high concentration in detergent. In the present study, recombinant Neurospora cr

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7

Samartzidou, Hrissi, Mahsa Mehrazin, Zhaohui Xu, Michael J. Benedik, and Anne H. Delcour. "Cadaverine Inhibition of Porin Plays a Role in Cell Survival at Acidic pH." Journal of Bacteriology 185, no. 1 (2003): 13–19. http://dx.doi.org/10.1128/jb.185.1.13-19.2003.

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ABSTRACT When grown at acidic pH, Escherichia coli cells secrete cadaverine, a polyamine known to inhibit porin-mediated outer membrane permeability. In order to understand the physiological significance of cadaverine excretion and the inhibition of porins, we isolated an OmpC mutant that showed resistance to spermine during growth and polyamine-resistant porin-mediated fluxes. Here, we show that the addition of exogenous cadaverine allows wild-type cells to survive a 30-min exposure to pH 3.6 better than cells expressing the cadaverine-insensitive OmpC porin. Competition experiments between s

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8

Martínez-Martínez, Luis, Alvaro Pascual, María del Carmen Conejo та ін. "Energy-Dependent Accumulation of Norfloxacin and Porin Expression in Clinical Isolates of Klebsiella pneumoniae and Relationship to Extended-Spectrum β-Lactamase Production". Antimicrobial Agents and Chemotherapy 46, № 12 (2002): 3926–32. http://dx.doi.org/10.1128/aac.46.12.3926-3932.2002.

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ABSTRACT The relationships between porin deficiency, active efflux of fluoroquinolones, and extended-spectrum β-lactamase (ESBL) production were determined for 53 clinical isolates of Klebsiella pneumoniae. Thirty-two ESBL-positive strains (including 22 strains expressing porins and 10 strains lacking porins) and 21 ESBL-negative strains were evaluated. Active efflux of norfloxacin was defined as a ≥50% increase in the accumulation of norfloxacin in the presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP) in comparison with the corresponding basal value in the absence of CCCP. The quino

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9

Paquet, Jean-Yves, Maria A. Diaz, Stephanie Genevrois, et al. "Molecular, Antigenic, and Functional Analyses of Omp2b Porin Size Variants of Brucella spp." Journal of Bacteriology 183, no. 16 (2001): 4839–47. http://dx.doi.org/10.1128/jb.183.16.4839-4847.2001.

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ABSTRACT Omp2a and Omp2b are highly homologous porins present in the outer membrane of the bacteria from the genus Brucella, a facultative intracellular pathogen. The genes coding for these proteins are closely linked in the Brucella genome and oriented in opposite directions. In this work, we present the cloning, purification, and characterization of four Omp2b size variants found in various Brucella species, and we compare their antigenic and functional properties to the Omp2a and Omp2b porins ofBrucella melitensis reference strain 16M. The variation of the Omp2a and Omp2b porin sequences am

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10

Kahlstatt, J., P. Reiß, T. Halbritter, L. O. Essen, U. Koert, and A. Heckel. "A light-triggered transmembrane porin." Chemical Communications 54, no. 69 (2018): 9623–26. http://dx.doi.org/10.1039/c8cc05221b.

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11

Ude, Johanna, Vishwachi Tripathi, Julien M. Buyck, et al. "Outer membrane permeability: Antimicrobials and diverse nutrients bypass porins in Pseudomonas aeruginosa." Proceedings of the National Academy of Sciences 118, no. 31 (2021): e2107644118. http://dx.doi.org/10.1073/pnas.2107644118.

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Gram-negative bacterial pathogens have an outer membrane that restricts entry of molecules into the cell. Water-filled protein channels in the outer membrane, so-called porins, facilitate nutrient uptake and are thought to enable antibiotic entry. Here, we determined the role of porins in a major pathogen, Pseudomonas aeruginosa, by constructing a strain lacking all 40 identifiable porins and 15 strains carrying only a single unique type of porin and characterizing these strains with NMR metabolomics and antimicrobial susceptibility assays. In contrast to common assumptions, all porins were di

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12

Derrick, Jeremy P., Rachel Urwin, Janet Suker, Ian M. Feavers, and Martin C. J. Maiden. "Structural and Evolutionary Inference from Molecular Variation in Neisseria Porins." Infection and Immunity 67, no. 5 (1999): 2406–13. http://dx.doi.org/10.1128/iai.67.5.2406-2413.1999.

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ABSTRACT The porin proteins of the pathogenic Neisseria species,Neisseria gonorrhoeae and Neisseria meningitidis, are important as serotyping antigens, putative vaccine components, and for their proposed role in the intracellular colonization of humans. A three-dimensional structural homology model for Neisseria porins was generated from Escherichia coli porin structures and N. meningitidis PorA and PorB sequences. The Neisseria sequences were readily assembled into the 16-strand β-barrel fold characteristic of porins, despite relatively low sequence identity with theEscherichia proteins. The

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13

Turner, Kelli L., Bethaney K. Cahill, Sarah K. Dilello, et al. "Porin Loss Impacts the Host Inflammatory Response to Outer Membrane Vesicles of Klebsiella pneumoniae." Antimicrobial Agents and Chemotherapy 60, no. 3 (2015): 1360–69. http://dx.doi.org/10.1128/aac.01627-15.

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Antibiotic-resistant strains ofKlebsiella pneumoniaeoften exhibit porin loss. In this study, we investigated how porin loss impacted the composition of secreted outer membrane vesicles as well as their ability to trigger proinflammatory cytokine secretion by macrophages. We hypothesize that porin loss associated with antibiotic resistance will directly impact both the composition of outer membrane vesicles and their interactions with phagocytic cells. Using clonally related clinical isolates of extended-spectrum beta-lactamase (ESBL)-positiveKlebsiella pneumoniaewith different patterns of pori

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14

García-Sureda, Laura, Antonio Doménech-Sánchez, Mariette Barbier, Carlos Juan, Joan Gascó, and Sebastián Albertí. "OmpK26, a Novel Porin Associated with Carbapenem Resistance in Klebsiella pneumoniae." Antimicrobial Agents and Chemotherapy 55, no. 10 (2011): 4742–47. http://dx.doi.org/10.1128/aac.00309-11.

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ABSTRACTClinical isolates ofKlebsiella pneumoniaeresistant to carbapenems are being isolated with increasing frequency. Loss of the expression of the major nonspecific porins OmpK35/36 is a frequent feature in these isolates. In this study, we looked for porins that could compensate for the loss of the major porins in carbapenem-resistant organisms. Comparison of the outer membrane proteins from twoK. pneumoniaeclinical isogenic isolates that are susceptible (KpCS-1) and resistant (KpCR-1) to carbapenems revealed the absence of OmpK35/36 and the presence of a new 26-kDa protein in the resistan

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15

Chen, Adrienne, and H. Steven Seifert. "Structure-Function Studies of the Neisseria gonorrhoeae Major Outer Membrane Porin." Infection and Immunity 81, no. 12 (2013): 4383–91. http://dx.doi.org/10.1128/iai.00367-13.

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ABSTRACTThe major outer membrane porin (PorB) expressed byNeisseria gonorrhoeaeplays multiple roles during infection, in addition to its function as an outer membrane pore. We have generated a panel of mutants ofN. gonorrhoeaestrain FA1090 expressing a variety of mutantporBgenes that all function as porins. We identified multiple regions of porin that are involved in its binding to the complement regulatory factors C4b-binding protein and factor H and confirmed that the ability to bind at least one factor is required for FA1090 to survive the bactericidal effects of human serum. We tested the

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16

Akhova, A. V., and A. G. Tkachenko. "ROLE OF POLYAMINES IN REDUCING THE OUTER MEMBRANE PERMEABILITY OF ESCHERICHIA COLI TO ANTIBIOTICS." Вестник Пермского университета. Серия «Биология»=Bulletin of Perm University. Biology, no. 3 (2020): 204–9. http://dx.doi.org/10.17072/1994-9952-2020-3-204-209.

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Various hydrophilic antibiotics enter the cells of gram-negative bacteria through porin channels, which can be blocked by polyamine cadaverine. In this paper, we studied the rate of porin-mediated transport and the intracellular concentration of the main biogenic polyamines of Escherichia coli cells subjected to fluoroquinolone antibiotics depending on the exposure time. Porin permeability sharply decreased in the first two hours of antibiotic exposure, after that the transport rate continued to decline, but at a lower rate. Free polyamines accumulated by the second hour of the exposure, then

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17

Samartzidou, Hrissi, and Anne H. Delcour. "Excretion of Endogenous Cadaverine Leads to a Decrease in Porin-Mediated Outer Membrane Permeability." Journal of Bacteriology 181, no. 3 (1999): 791–98. http://dx.doi.org/10.1128/jb.181.3.791-798.1999.

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ABSTRACT The permeability of the outer membrane of Escherichia coli to hydrophilic compounds is controlled by porin channels. Electrophysiological experiments showed that polyamines inhibit ionic flux through cationic porins when applied to either side of the membrane. Externally added polyamines, such as cadaverine, decrease porin-mediated fluxes of β-lactam antibiotics in live cells. Here we tested the effects of endogenously expressed cadaverine on the rate of permeation of cephaloridine through porins, by manipulating in a pH-independent way the expression of the cadBA operon, which encode

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18

Diaz-Quiñonez, Alberto, Natalia Martin-Orozco, Armando Isibasi, and Vianney Ortiz-Navarrete. "Two Salmonella OmpC Kb-Restricted Epitopes for CD8+-T-Cell Recognition." Infection and Immunity 72, no. 5 (2004): 3059–62. http://dx.doi.org/10.1128/iai.72.5.3059-3062.2004.

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ABSTRACT We report the identification of two peptides from Salmonella OmpC porin that can bind to major histocompatibility complex class I Kb molecules and are targets of cytotoxic T lymphocytes from Salmonella-infected mice. These peptides are conserved in gram-negative bacterial porins and are the first Salmonella porin-specific epitopes described for possible CD8+-T-cell elimination of infected cells.

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Arunmanee, Wanatchaporn, Monisha Pathania, Alexandra S. Solovyova, et al. "Gram-negative trimeric porins have specific LPS binding sites that are essential for porin biogenesis." Proceedings of the National Academy of Sciences 113, no. 34 (2016): E5034—E5043. http://dx.doi.org/10.1073/pnas.1602382113.

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The outer membrane (OM) of gram-negative bacteria is an unusual asymmetric bilayer with an external monolayer of lipopolysaccharide (LPS) and an inner layer of phospholipids. The LPS layer is rigid and stabilized by divalent cation cross-links between phosphate groups on the core oligosaccharide regions. This means that the OM is robust and highly impermeable to toxins and antibiotics. During their biogenesis, OM proteins (OMPs), which function as transporters and receptors, must integrate into this ordered monolayer while preserving its impermeability. Here we reveal the specific interactions

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PELLINEN, Teijo, Helena AHLFORS, Nicolas BLOT, and Guy CONDEMINE. "Topology of the Erwinia chrysanthemi oligogalacturonate porin KdgM." Biochemical Journal 372, no. 2 (2003): 329–34. http://dx.doi.org/10.1042/bj20030027.

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The Erwinia chrysanthemi oligogalacturonate-specific monomeric porin, KdgM, does not present homology with any porins of known structure. A model of this protein, based on sequence similarity and the amphipathy profile, was constructed. The model depicts a β-barrel composed of 14 antiparallel β-strands. The accuracy of this model was tested by the chemical labelling of cysteine residues introduced by site-directed mutagenesis. The protein has seven surface-exposed loops. They are rather small with the exception of one, loop L6. Deletion of this loop allowed the entry of maltopentaose into the

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Galdiero, Massimiliano, Mariateresa Vitiello, Emma Sanzari та ін. "Porins from Salmonella enterica Serovar Typhimurium Activate the Transcription Factors Activating Protein 1 and NF-κB through the Raf-1-Mitogen-Activated Protein Kinase Cascade". Infection and Immunity 70, № 2 (2002): 558–68. http://dx.doi.org/10.1128/iai.70.2.558-568.2002.

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ABSTRACT In this study we examined the ability of Salmonella enterica serovar Typhimurium porins to activate activating protein 1 (AP-1) and nuclear factor κB (NF-κB) through the mitogen-activated protein kinase (MAPK) cascade, and we identified the AP-1-induced protein subunits. Our results demonstrate that these enzymes may participate in cell signaling pathways leading to AP-1 and NF-κB activation following porin stimulation of cells. Raf-1 was phosphorylated in response to the treatment of U937 cells with porins; moreover, the porin-mediated increase in Raf-1 phosphorylation is accompanied

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22

Ontiveros-Padilla, Luis, Alberto García-Lozano, Araceli Tepale-Segura, et al. "CD4+ and CD8+ Circulating Memory T Cells Are Crucial in the Protection Induced by Vaccination with Salmonella Typhi Porins." Microorganisms 9, no. 4 (2021): 770. http://dx.doi.org/10.3390/microorganisms9040770.

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Salmonella enterica serovar Typhi (S. Typhi) porins, OmpC and OmpF, are potent inducers of the immune response against S. Typhi in mice and humans. Vaccination with porins induces the protection against 500 LD50 of S. Typhi, life-lasting bactericidal antibodies and effector T cell responses in mice; however, the nature of the memory T cell compartment and its contribution to protection remains unknown. In this work, we firstly observed that vaccination with porins induces in situ (skin) CD4+ and CD8+ T cell responses. Analysis of the porin-specific functional responses of skin CD4+ and CD8+ T

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Lal, R., H. Kim, R. M. Garavito, and M. F. Arnsdorf. "Imaging of reconstituted biological channels at molecular resolution by atomic force microscopy." American Journal of Physiology-Cell Physiology 265, no. 3 (1993): C851—C856. http://dx.doi.org/10.1152/ajpcell.1993.265.3.c851.

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Using atomic force microscopy (AFM), we obtained high-resolution surface images of the bacterial outer membrane channels Escherichia coli OmpF porin and Bordetella pertussis porin that were reconstituted in artificial bilayer membranes as two-dimensional crystalline arrays. These porins were chosen because they are among the most extensively studied proteins of this type and are known for their well-defined crystalline nature in the native membrane. Such reconstituted membrane proteins are ideal specimens to assess the suitability and resolution of AFM for imaging biomembranes and associated p

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Somalinga, Vijayakumar, and William W. Mohn. "Rhodococcus jostii Porin A (RjpA) Functions in Cholate Uptake." Applied and Environmental Microbiology 79, no. 19 (2013): 6191–93. http://dx.doi.org/10.1128/aem.01242-13.

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ABSTRACTRjpA inRhodococcus jostiiis the ortholog of a channel-forming porin, MspA. Deletion ofrjpAdelayed growth ofR. jostiion cholate but not on cholesterol. Eventual growth on cholate involved increased expression of other porins, namely, RjpB, RjpC, and RjpD. Porins appear essential for the uptake of bile acids by mycolic acid bacteria.

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Jap, Bing K. "3-D structure analysis of PhoE porin." Proceedings, annual meeting, Electron Microscopy Society of America 44 (August 1986): 164–65. http://dx.doi.org/10.1017/s042482010014244x.

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The outer membrane of Escherichia coli contains a variety of pore-forming proteins called porins. These proteins have similar molecular weight and amino acid composition, but have substantially different chemical specificities for restricting free diffusion of aqueous solutes. One porin, called PhoE, is preferentially expressed under growth conditions involving phosphate starvation. PhoE porin serves not only as a nonspecific channel for small solutes, but also facilitates the diffusion of phosphate containing solutes as well as other negatively charged compounds.

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Jones, Christopher M., and Michael Niederweis. "Role of Porins in Iron Uptake by Mycobacterium smegmatis." Journal of Bacteriology 192, no. 24 (2010): 6411–17. http://dx.doi.org/10.1128/jb.00986-10.

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ABSTRACT Many bacteria rely on siderophores to extract iron from the environment. However, acquisition of iron-loaded siderophores is dependent on high-affinity uptake systems that are not produced under high-iron conditions. The fact that bacteria are able to maintain iron homeostasis in the absence of siderophores indicates that alternative iron acquisition systems exist. It has been speculated that such low-affinity uptake of iron in Gram-negative bacteria includes diffusion of iron ions or chelates across the outer membrane through porins. The outer membrane of the saprophytic Mycobacteriu

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El-Khatib, Mariam, Chady Nasrallah, Julie Lopes, et al. "Porin self-association enables cell-to-cell contact in Providencia stuartii floating communities." Proceedings of the National Academy of Sciences 115, no. 10 (2018): E2220—E2228. http://dx.doi.org/10.1073/pnas.1714582115.

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The gram-negative pathogen Providencia stuartii forms floating communities within which adjacent cells are in apparent contact, before depositing as canonical surface-attached biofilms. Because porins are the most abundant proteins in the outer membrane of gram-negative bacteria, we hypothesized that they could be involved in cell-to-cell contact and undertook a structure-function relationship study on the two porins of P. stuartii, Omp-Pst1 and Omp-Pst2. Our crystal structures reveal that these porins can self-associate through their extracellular loops, forming dimers of trimers (DOTs) that

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Fernando, Dinesh, George Zhanel, and Ayush Kumar. "Antibiotic Resistance and Expression Of Resistance-Nodulation-Division Pump- and Outer Membrane Porin-Encoding Genes inAcinetobacterSpecies Isolated from Canadian Hospitals." Canadian Journal of Infectious Diseases and Medical Microbiology 24, no. 1 (2013): 17–21. http://dx.doi.org/10.1155/2013/696043.

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BACKGROUND: Bacterial pathogens belonging to the genusAcinetobactercause serious infections in immunocompromised individuals that are very difficult to treat due to their extremely high resistance to many antibiotics.OBJECTIVE: To investigate the role of resistance-nodulation-division (RND) pumps and porins in the antibiotic resistance ofAcinetobacterspecies collected from Canadian hospitals.METHODS: Clinical isolates ofAcinetobacterspecies collected from Canadian hospitals were analyzed for the expression of genes encoding RND pumps (adeB,adeG,adeJ,AciBau_2746and AciBau_2436) and outer membra

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Chistyulin, D. K., O. D. Novikova, E. A. Zelepuga, et al. "An Abnormally High Closing Potential of the OMPF Porin Channel from Yersinia Ruckeri: The Role of Charged Residues and Intramolecular Bonds." Acta Naturae 11, no. 3 (2019): 89–98. http://dx.doi.org/10.32607/20758251-2019-11-3-89-98.

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Electrophysiological experiments on bilayer lipid membranes showed that the isolated outer membrane major porin of Yersinia ruckeri (YrOmpF) exhibits activity typical of porins from Gram-negative bacteria, forming channels with a mean conductance of 230 pS (in 0.1 M KCl) and slight asymmetry with respect to the applied voltage. Under acidic conditions (up to pH = 3.0), there was no significant decrease in the total conductance of the YrOmpF channel reconstituted into the bilayer. The studied channel significantly differed from the porins of other bacteria by high values of its critical closing

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Martínez-Martínez, Luis, Alvaro Pascual, Santiago Hernández-Allés та ін. "Roles of β-Lactamases and Porins in Activities of Carbapenems and Cephalosporins against Klebsiella pneumoniae". Antimicrobial Agents and Chemotherapy 43, № 7 (1999): 1669–73. http://dx.doi.org/10.1128/aac.43.7.1669.

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ABSTRACT Two clinical isolates of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae were noted to be less susceptible than expected to imipenem. Both were missing outer membrane proteins that serve as channels for antibiotic entry. The role of β-lactamase in resistance was investigated by eliminating the original ESBL and introducing plasmids encoding various ESBLs and AmpC β-lactamase types, by studying the effect of an increased inoculum, and by evaluating interactions with β-lactamase inhibitors. The contribution of porin deficiency was investigated by restoring a functio

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Jap, B. K., P. J. Walian, and K. H. Downing. "Image of PhoE Porin in projection at 3.5Å resolution." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 818–19. http://dx.doi.org/10.1017/s0424820100156067.

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The outer membrane of Gram-negative bacteria, such as E. coli, contains a high density of a family of pore-forming proteins, which are often called porins. One member of the family, PhoE porin, is expressed under conditions of phosphate starvation, and has been shown to favor the transport of phosphate-containing compounds and negatively charged molecules. The three-dimensional (3-D) structure of PhoE porin obtained from two-dimensional crystals, negatively stained with uranyl acetate, has been determined to a resolution of about 18Å. The projected structure of glucose-embedded PhoE porin has

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Begic, Sanela, and Elizabeth A. Worobec. "Site-directed mutagenesis studies to probe the role of specific residues in the external loop (L3) of OmpF and OmpC porins in susceptibility of Serratia marcescens to antibiotics." Canadian Journal of Microbiology 53, no. 6 (2007): 710–19. http://dx.doi.org/10.1139/w07-018.

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Serratia marcescens is a nosocomial bacterium with natural resistance to a broad spectrum of antibiotics, making treatment challenging. One factor contributing to this natural antibiotic resistance is reduced outer membrane permeability, controlled in part by OmpF and OmpC porin proteins. To investigate the direct role of these porins in the diffusion of antibiotics across the outer membrane, we have created an ompF–ompC porin-deficient strain of S. marcescens. A considerable similarity between the S. marcescens porins and those from other members of Enterobacteriaceae was detected by sequence

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Barnett, James Paul, David John Scanlan, and Claudia Andrea Blindauer. "Identification of major zinc-binding proteins from a marine cyanobacterium: insight into metal uptake in oligotrophic environments." Metallomics 6, no. 7 (2014): 1254–68. http://dx.doi.org/10.1039/c4mt00048j.

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The open ocean cyanobacteriumSynechococcussp. WH8102 thrives at extremely low zinc concentrations. Metalloproteomics experiments have identified an outer-membrane bound porin with zinc-binding ability that is upregulated at low zinc levels, suggesting a role for porins in highly efficient zinc uptake.

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Kumagai, Yumi, Haibin Huang, and Yasuko Rikihisa. "Expression and Porin Activity of P28 and OMP-1F during Intracellular Ehrlichia chaffeensis Development." Journal of Bacteriology 190, no. 10 (2008): 3597–605. http://dx.doi.org/10.1128/jb.02017-07.

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ABSTRACT Ehrlichia chaffeensis, an obligatory intracellular gram-negative bacterium, must take up various nutrients and metabolic compounds because it lacks many genes involved in metabolism. Nutrient uptake by a gram-negative bacterium occurs primarily through pores or channels in the bacterial outer membrane. Here we demonstrate that isolated E. chaffeensis outer membranes have porin activities, as determined by a proteoliposome swelling assay. The activity was partially blocked by an antibody that recognizes the two most abundant outer membrane proteins, P28/OMP-19 and OMP-1F/OMP-18. Both p

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Sugawara, Etsuko, Seiji Kojima та Hiroshi Nikaido. "Klebsiella pneumoniae Major Porins OmpK35 and OmpK36 Allow More Efficient Diffusion of β-Lactams than Their Escherichia coli Homologs OmpF and OmpC". Journal of Bacteriology 198, № 23 (2016): 3200–3208. http://dx.doi.org/10.1128/jb.00590-16.

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ABSTRACTKlebsiella 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. Unfortunately, the properties ofK. pneumoniaeporin channel

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CHEVALIER, Jacqueline, Monique MALLÉA, and Jean-Marie PAGÈS. "Comparative aspects of the diffusion of norfloxacin, cefepime and spermine through the F porin channel of Enterobacter cloacae." Biochemical Journal 348, no. 1 (2000): 223–27. http://dx.doi.org/10.1042/bj3480223.

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In Enterobacteriaceae, the permeability of the outer membrane to hydrophilic antibiotics is associated with the presence of pore-forming proteins. We tested the diffusion of the fluoroquinolone norfloxacin in four Enterobacter cloacae strains: a clinical isolate and three derivatives variously producing or lacking the D and F porins. We analysed the entry of norfloxacin into E. cloacae cells in the presence of either the polyamine spermine or the recently developed cefepime, which are known to penetrate through the Escherichia coli OmpF porin. Uptake of the fluoroquinolone was decreased in bot

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Sharbati-Tehrani, Soroush, Joachim Stephan, Gudrun Holland, Bernd Appel, Michael Niederweis, and Astrid Lewin. "Porins limit the intracellular persistence of Mycobacterium smegmatis." Microbiology 151, no. 7 (2005): 2403–10. http://dx.doi.org/10.1099/mic.0.27969-0.

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The genus Mycobacterium comprises highly pathogenic as well as opportunistic or apathogenic species exhibiting a great variability with respect to their ability to persist or multiply within monocytic host cells. The impact of the permeability of the mycobacterial outer membrane on intracellular persistence was studied. For this purpose, a Mycobacterium smegmatis mutant with a deletion of the major porin gene mspA and a second mutant lacking mspA and the homologous porin gene mspC were used. Deletion of mspA together with mspC significantly enhanced intracellular persistence in murine bone mar

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Housden, Nicholas G., Jonathan T. S. Hopper, Natalya Lukoyanova, et al. "Intrinsically Disordered Protein Threads Through the Bacterial Outer-Membrane Porin OmpF." Science 340, no. 6140 (2013): 1570–74. http://dx.doi.org/10.1126/science.1237864.

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Porins are β-barrel outer-membrane proteins through which small solutes and metabolites diffuse that are also exploited during cell death. We have studied how the bacteriocin colicin E9 (ColE9) assembles a cytotoxic translocon at the surface of Escherichia coli that incorporates the trimeric porin OmpF. Formation of the translocon involved ColE9’s unstructured N-terminal domain threading in opposite directions through two OmpF subunits, capturing its target TolB on the other side of the membrane in a fixed orientation that triggers colicin import. Thus, an intrinsically disordered protein can

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Howard, S. Peter, and Heather G. Meiklejhon. "Effect of mutations in the general secretory pathway on outer membrane protein and surface layer assembly in Aeromonas spp." Canadian Journal of Microbiology 41, no. 6 (1995): 525–32. http://dx.doi.org/10.1139/m95-069.

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Mutations in the exeC-N operon of Aeromonas hydrophila, which block extracellular protein secretion, also result in large decreases in the level of the major outer membrane porin, protein II. Immunoblot analysis demonstrated that the porin missing from the outer membrane of the mutant was not accumulating elsewhere in the cell. Pulse-chase and immunoprecipitation analyses showed that the porin was as stable in the mutant as in the wild type, but that far less porin was synthesized in the exe mutants. The relationship between extracellular secretion involving the exe genes and the assembly of o

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Liu, XueQiao, and Thomas Ferenci. "Regulation of Porin-Mediated Outer Membrane Permeability by Nutrient Limitation in Escherichia coli." Journal of Bacteriology 180, no. 15 (1998): 3917–22. http://dx.doi.org/10.1128/jb.180.15.3917-3922.1998.

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ABSTRACT OmpF and OmpC porins were differentially regulated by nutrient limitation and growth rate in glucose- or nitrogen-limited chemostat cultures of Escherichia coli. Transcriptional and translational ompF fusions showed a sharp peak of expression under glucose limitation at D = 0.3 h−1, with lower amounts at lower and higher growth rates. The peak of OmpR-dependent transcriptional stimulation ofompF under glucose limitation in minimal salts media was about 20-fold above nutrient excess levels and 3-fold higher than that achieved with low osmolarity. Analysis of outer membrane protein leve

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Batchelor, Eric, Don Walthers, Linda J. Kenney, and Mark Goulian. "The Escherichia coli CpxA-CpxR Envelope Stress Response System Regulates Expression of the Porins OmpF and OmpC." Journal of Bacteriology 187, no. 16 (2005): 5723–31. http://dx.doi.org/10.1128/jb.187.16.5723-5731.2005.

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ABSTRACT We performed transposon mutagenesis of a two-color fluorescent reporter strain to identify new regulators of the porin genes ompF and ompC in Escherichia coli. Screening of colonies by fluorescence microscopy revealed numerous mutants that exhibited interesting patterns of porin expression. One mutant harbored an insertion in the gene encoding the histidine kinase CpxA, the sensor for a two-component signaling system that responds to envelope stress. The cpxA mutant exhibited increased transcription of ompC and a very strong decrease in transcription of ompF under conditions in which

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Bornet, Charléric, Anne Davin-Regli, Claude Bosi, Jean-Marie Pages, and Claude Bollet. "Imipenem Resistance of Enterobacter aerogenes Mediated by Outer Membrane Permeability." Journal of Clinical Microbiology 38, no. 3 (2000): 1048–52. http://dx.doi.org/10.1128/jcm.38.3.1048-1052.2000.

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Multidrug-resistant Enterobacter aerogenes strains are increasingly isolated in Europe and especially in France. Treatment leads to imipenem resistance, because of a lack of porin. We studied the evolution of resistance in 29 strains isolated from four patients during their clinical course. These strains belonged to the prevalent epidemiological type observed in France in previous studies (C. Bosi, et al., J. Clin. Microbiol. 37:2165–2169, 1999; A. Davin-Regli et al., J. Clin. Microbiol. 34:1474–1480, 1996). They also harbored a TEM-24 extended-spectrum β-lactamase-coding gene. Thirteen strain

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Frenzel, Elrike, Stefan Schmidt, Michael Niederweis, and Katrin Steinhauer. "Importance of Porins for Biocide Efficacy against Mycobacterium smegmatis." Applied and Environmental Microbiology 77, no. 9 (2011): 3068–73. http://dx.doi.org/10.1128/aem.02492-10.

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ABSTRACTMycobacteria are among the microorganisms least susceptible to biocides but cause devastating diseases, such as tuberculosis, and increasingly opportunistic infections. The exceptional resistance of mycobacteria to toxic solutes is due to an unusual outer membrane, which acts as an efficient permeability barrier, in synergy with other resistance mechanisms. Porins are channel-forming proteins in the outer membrane of mycobacteria. In this study we used the alamarBlue assay to show that the deletion of Msp porins in isogenic mutants increased the resistance ofMycobacterium smegmatisto i

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Jap, B. K., and P. J. Walian. "Structure and functional mechanism of porins." Physiological Reviews 76, no. 4 (1996): 1073–88. http://dx.doi.org/10.1152/physrev.1996.76.4.1073.

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Cellular organisms such as gram-negative bacteria are enclosed by a dual lipid bilayer system. The outer membranes of the dual bilayer envelopes predominantly contain large numbers of water-filled transmembrane protein channels known as porins. The recent availability of the molecular structures of several bacterial porins has provided the opportunity for comparing the results of a wide range of functional studies with the atomic level structural details of these membrane channels. Taken together, the structure and function data present the most comprehensive set of boundary conditions availab

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Suelter, Corey S., and Nancy D. Hanson. "OmpC regulation differs between ST131 and non-ST131 Escherichia coli clinical isolates and involves differential expression of the small RNA MicC." Journal of Antimicrobial Chemotherapy 75, no. 5 (2020): 1151–58. http://dx.doi.org/10.1093/jac/dkz566.

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Abstract Background Virulence genes and the expression of resistance mechanisms undoubtedly play a role in the successful spread of the pandemic clone Escherichia coli ST131. Porin down-regulation is a chromosomal mechanism associated with antibiotic resistance. Translation of porin proteins can be impacted by modifications in mRNA half-life and the interaction among small RNAs (sRNAs), the porin transcript and the sRNA chaperone Hfq. Modifications in the translatability of porin proteins could impact the fitness and therefore the success of E. coli ST131 isolates in the presence of antibiotic

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de María, Nuria, Ángeles Guevara, M. Teresa Serra, et al. "Putative Porin of Bradyrhizobium sp. (Lupinus) Bacteroids Induced by Glyphosate." Applied and Environmental Microbiology 73, no. 16 (2007): 5075–82. http://dx.doi.org/10.1128/aem.00392-07.

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ABSTRACT Application of glyphosate (N-[phosphonomethyl] glycine) to Bradyrhizobium sp. (Lupinus)-nodulated lupin plants caused modifications in the protein pattern of bacteroids. The most significant change was the presence of a 44-kDa polypeptide in bacteroids from plants treated with the higher doses of glyphosate employed (5 and 10 mM). The polypeptide has been characterized by the amino acid sequencing of its N terminus and the isolation and nucleic acid sequencing of its encoding gene. It is putatively encoded by a single gene, and the protein has been identified as a putative porin. Prot

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Moya-Torres, Aniel, Michael R. Mulvey, Ayush Kumar, Ivan J. Oresnik, and Ann Karen C. Brassinga. "The lack of OmpF, but not OmpC, contributes to increased antibiotic resistance in Serratia marcescens." Microbiology 160, no. 9 (2014): 1882–92. http://dx.doi.org/10.1099/mic.0.081166-0.

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The environmental organism Serratia marcescens is one of the primary causes of numerous nosocomial outbreaks and opportunistic infections. Multi-drug resistance is now a common feature among S. marcescens clinical isolates, complicating the efficacy of treatment. Recent reports have attributed antibiotic resistance to altered porin expression as well as perturbation of the intrinsic AmpC beta-lactamase production pathway. In this study, we aimed to genetically correlate the absence of OmpF and OmpC classical porins with increased antibiotic resistance. In generating isogenic porin mutant strai

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Charrel, R. N., J. M. Pagès, P. De Micco, and M. Mallea. "Prevalence of outer membrane porin alteration in beta-lactam-antibiotic-resistant Enterobacter aerogenes." Antimicrobial Agents and Chemotherapy 40, no. 12 (1996): 2854–58. http://dx.doi.org/10.1128/aac.40.12.2854.

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We evaluated the prevalence of impermeability as a mechanism associated with resistance against beta-lactam antibiotics in members of the family Enterobacteriaceae. During a 1-year period, 80 strains were selected from 3,110 routinely isolated strains according to their noticeable cross-resistance pattern to cephalosporins. They were tested for (i) outer membrane nonspecific porins involved in the entry of small hydrophilic molecules; (ii) the MICs of cefepime, cefotaxime, imipenem, and moxalactam; and (iii) beta-lactamase production. Immunological investigations using specific probes showed t

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Henn, C., A. Hönger, S. Cowan, J. P. Rosenbusch, and A. Engel. "Two-dimensional porin OMPF-lipid crystals: A comparison of EM and x-ray data." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 1 (1992): 438–39. http://dx.doi.org/10.1017/s0424820100122599.

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In Escherichia coli (E.coli) cells porins represent a major component of the outer membrane. Embedded in the lipid bilayer, these channel forming proteins facilitate the diffusion of solutes up to a mass of 600 Da. Porins OmpC, OmpF and PhoE exhibit a high sequence homology, whereas the sequence of LamB, the maltose channel, is different. Nevertheless, all E.coli porins have pronounced common features: (i) the wall of the cylindrical channel is in a β-sheet conformation with the antiparallel β-strands running at approximately 45 degrees;(ii) functional porins exist as trimers, and (iii) voltag

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Wyllie, Susan, Richard H. Ashley, David Longbottom, and Alan J. Herring. "The Major Outer Membrane Protein of Chlamydia psittaci Functions as a Porin-Like Ion Channel." Infection and Immunity 66, no. 11 (1998): 5202–7. http://dx.doi.org/10.1128/iai.66.11.5202-5207.1998.

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ABSTRACT The major outer membrane protein (MOMP) of Chlamydiaspecies shares several biochemical properties with classical porin proteins. Secondary structure analysis by circular dichroism now reveals that MOMP purified from Chlamydia psittaci has a predominantly β-sheet content (62%), which is also typical of bacterial porins. Can MOMP form functional ion channels? To directly test the “porin channel” hypothesis at the molecular level, the MOMP was reconstituted into planar lipid bilayers, where it gave rise to multibarreled channels, probably trimers, which were modified by an anti-MOMP mono

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