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Colicins (0):
Recent article
Colicins
Journal of Bacteriology (192)13 2010
Abstract
We show that overproduction of CreD in a Cet2 strain results from hyperactivation of the CreBC two-component regulator, but CreD overproduction is not responsible for the Cet2 phenotype. Through microarray analysis and gene knockout and overexpression studies, we show that overexpression of another...
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PMID: 20418396
PDF is available here.
PDF is available here.
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Biochemistry (Washington) (49)23 2010
Abstract
We considered that protons may traverse a separate pathway but were unable to find any evidence for one. Manipulations that interfere with ionic conduction, such as replacing some of the water in the pore with a nonelectrolyte, reduce the proton current along with the ionic current. Lipids have been...
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PMID: 20459128
PDF is available here.
PDF is available here.
Abstract
We deployed a disulfide-trapping strategy on a noncognate complex between the colicin E9 endonuclease (E9 DNase) and immunity protein 2 (Im2), which is seven orders of magnitude weaker binding than the cognate femtomolar E9 DNase-Im9 interaction. The 1.77 A crystal structure of the E9 DNase-Im2 comp...
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PMID: 20479265
PDF is available here.
PDF is available here.
Abstract
We found that many chromosomal genes and environmental stimuli affected MarA-mediated antibiotic resistance. Seven genes affected resistance mediated by MarA in an antibiotic-specific way; these were mostly genes encoding unrelated enzymes, transporters, and unknown proteins. Other genes affected Ma...
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PMID: 20211899
PDF is available here.
PDF is available here.
Abstract
We report here the NMR assignment and backbone dynamics of this domain in solution. The chemical shifts identify ten alpha-helices that match those observed in the crystal structure, while the (15)N{(1)H} NOEs show differential fast mobility for some of the inter-helical loops and the chain ends. Th...
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PMID: 19941091
PDF is available here.
PDF is available here.
Abstract
Colicins are water soluble toxins secreted by E. coli cells to kill other E. coli and related species. To do this they need to cross the outer membrane, periplasm and inner membrane. Pore forming colicins, as their name suggests form a voltage dependent pore in the inner membrane. This chapter deals...
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PMID: 20687482
PDF is available here.
PDF is available here.
Abstract
We provide the first biochemical evidence of the existence of a family of structure-related antimicrobial peptides, the siderophore-microcins, in the Enterobacteriaceae family. We isolated and characterized two novel siderophore-microcins, MccM and MccH47, previously characterized through genetic st...
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PMID: 19884380
PDF is available here.
PDF is available here.
Abstract
BMC Microbiology (9)1 2009
Abstract
Six colicin-producing, yet otherwise isogenic, E. coli strains were administered and established in the large intestine of streptomycin-treated mice. The strains' persistence, population density, and doubling time were monitored over a period of 112 days. Early in the experiment only minor differenc...
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PMID: 19674447
PDF is available here.
PDF is available here.
Abstract
Hemolytic Escherichia, enteropathogenic E. coli, Shigella spp., and Salmonella spp. were isolated in 47.3%, 12.2%, 18.3%, and 1.8% of patients with AEI, respectively. The cause of AEI was identified in 77.1% of cases. Bifidumbacterin had good therapeutic effect on infections caused by pathogenic E....
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PMID: 19623719
PDF is available here.
PDF is available here.
Biochemical Society transactions (36)Pt 6 2008
Abstract
We review key interactions in the assembly of this 'colicin translocon' and discuss the key role disorder plays in achieving uptake....
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PMID: 19021565
PDF is available here.
PDF is available here.
Abstract
We wish to know how this structure changes to form a channel in a lipid bilayer. Although there is evidence that the open channel has four transmembrane segments (H8, H9, and parts of H1 and H6-H7), their arrangement relative to the pore is largely unknown. Given the lack of a detailed structural mo...
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PMID: 19029376
PDF is available here.
PDF is available here.
Journal of Food Protection (71)12 2008
Abstract
Colicin E1 (ColE1) is a bacteriocin produced by and effective against Escherichia coli and related species. The current study examined ColE1 as a potential intervention strategy for controlling E. coli O157:H7 contamination on beef carcasses. Untrimmed beef round roasts were cut into sample sizes of...
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PMID: 19244907
PDF is available here.
PDF is available here.
Biopolymers (89)11 2008
Abstract
Protein-protein association involves many interface interactions, but they do not contribute equally. Ala scanning experiments reveal that only a few mutations significantly lower binding affinity. These key residues, which appear to drive protein-protein association, are called hot-spot residues. M...
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PMID: 18546205
PDF is available here.
PDF is available here.
Abstract
The construction of hybrids between colicins U and Y and the mutagenesis of the colicin Y gene (cya) have revealed amino acid residues important for interactions between colicin Y and its cognate immunity protein (Cyi). Four such residues (I578, T582, Y586 and V590) were found in helices 8 and 9 of t...
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PMID: 18803667
PDF is available here.
PDF is available here.
Journal of Biological Chemistry (283)37 2008
Abstract
We crystallized colicin M and determined the structure at 1.7A resolution using x-ray crystallography. The protein has a novel structure composed of three domains with distinct functions. The N-domain is a short random coil and contains the exposed TonB box. The central domain includes a hydrophobic...
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PMID: 18640984
PDF is available here.
PDF is available here.
EMBO Journal (27)15 2008
Abstract
The OmpF porin in the Escherichia coli outer membrane (OM) is required for the cytotoxic action of group A colicins, which are proposed to insert their translocation and active domains through OmpF pores. A crystal structure was sought of OmpF with an inserted colicin segment. A 1.6 A OmpF structure...
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PMID: 18636093
PDF is available here.
PDF is available here.
Molecular Microbiology (69)4 2008
Abstract
We show here that the periplasmic FkpA chaperone is required for killing Escherichia coli by colicin M entering cells from the outside. Highly active colicin M preparations were inactive against fkpA mutant cells; 10(4)-fold dilutions killed fkpA(+) cells. Three previously isolated spontaneous mutan...
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PMID: 18554332
PDF is available here.
PDF is available here.
FEBS Letters (582)17 2008
Abstract
We report here that the specific 27 consecutive residues of the T-domain of colicin N known to bind to the helper protein TolA in target cells also interacts intramolecularly with folded regions of colicin N. We suggest that this specific self-recognition helps intrinsically disordered domains to bu...
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PMID: 18573254
PDF is available here.
PDF is available here.
Abstract
I (LSPA6-LI) genotype, while those of PTs 23, 45, 67, and 74 belonged to LSPA6 lineage II (LSPA6-LII) genotypes. This correlation was maintained when additional strains of each PT were tested. E. coli O157:H7 strains with the LSPA6-LI genotype were much more common in the collection than were the LS...
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PMID: 18487402
PDF is available here.
PDF is available here.
Molecular Microbiology (69)2 2008
Abstract
We studied the effects of colicin E3 cleavage on ribosome functions by analysing individual steps of protein synthesis. We find that the cleavage affects predominantly the elongation step. The inhibitory effect of colicin E3 cleavage originates from the accumulation of sequential impaired decoding e...
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PMID: 18485067
PDF is available here.
PDF is available here.
Journal of Molecular Biology (379)4 2008
Abstract
We addressed for the first time the energetics of Im protein recognition by colicin DNases through a combination of E9 DNase alanine scanning and double-mutant cycles (DMCs) coupled with kinetic and calorimetric analyses of cognate Im9 and non-cognate Im2 binding, as well as computational analysis o...
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PMID: 18471830
PDF is available here.
PDF is available here.
Microbiology (154)Pt 6 2008
Abstract
These results suggest that the evolution of dual SOS boxes elegantly accomplishes the task of increasing the amount of toxin produced by a cell while decreasing the rate of uninduced production, effectively reducing the cost of colicin production. This hypothesis may explain why such a promoter moti...
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PMID: 18524933
PDF is available here.
PDF is available here.
FEMS Microbiology Letters (283)1 2008
Abstract
We propose that the SOS response indirectly regulates thermoregulation of colicin K (and possibly of the other examined colicins). Two LexA dimers bind cooperatively with high affinity to the two overlapping LexA boxes in a temperature-independent manner. At 22 degrees C the relative degree of repre...
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PMID: 18399998
PDF is available here.
PDF is available here.
Journal of Bacteriology (190)12 2008
Abstract
We constructed an inactive disulfide-locked mutant ColE9 (ColE9(s-s)) that binds to BtuB and can be reduced with dithiothreitol (DTT) to synchronize cell killing. By introducing unique enterokinase (EK) cleavage sites in ColE9(s-s), we showed that the first 61 residues of the NDR were inaccessible t...
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PMID: 18408035
PDF is available here.
PDF is available here.
FEMS Microbiology Letters (282)1 2008
Abstract
The Tol system is an interactive set of envelope proteins that includes both outer and cytoplasmic membrane proteins. Central to this system is TolA, which spans the periplasmic space to communicate with residents of each membrane. To identify motifs involved in the protein/protein interactions thro...
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PMID: 18355278
PDF is available here.
PDF is available here.
ChemBioChem (9)6 2008
Abstract
An approach is presented to selectively label the methionines of the colicin E1 and B channel domains, each about 200 residues in size, and use them for oriented solid-state NMR investigations. By combining site-directed mutagenesis, bacterial overexpression in a methionine auxotroph E. coli strain...
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PMID: 18338351
PDF is available here.
PDF is available here.
Journal of Molecular Biology (378)1 2008
Abstract
Colicin A (ColA) is a water-soluble toxin that forms a voltage-gated channel in the cytoplasmic membrane of Escherichia coli. Until now, two models were proposed for the closed channel state: the umbrella model and the penknife model. Mutants of ColA, each containing a single cysteine, were labeled...
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PMID: 18353363
PDF is available here.
PDF is available here.
Abstract
We show that, in 2D crystals, colicin is found outside the porin trimer, suggesting that translocation may occur at the protein-lipid interface. The major lipid of the outer leaflet interface is lipopolysaccharide (LPS). It is further shown that colicin N binding displaces OmpF-bound LPS. The N-term...
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PMID: 18334212
PDF is available here.
PDF is available here.
Abstract
We investigate evolution within toxic bacterial biofilms using an agent-based simulation that represents a nontransitive community containing three populations of Escherichia coli. In structured, nontransitive communities, strains evolve that do not maximize their competitive ability: They do not re...
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PMID: 18039324
PDF is available here.
PDF is available here.
Abstract
We report that the colicin channel, particularly the colicin A channel, is selective for protons over other cations (and anions) by many orders of magnitude. This was deduced from measurements of reversal potentials in pH gradients across planar lipid bilayers containing these channels. For example,...
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PMID: 18205407
PDF is available here.
PDF is available here.
Biochimica et Biophysica Acta (1778)7-8 2008
Abstract
Bacteria, as well as higher organisms such as sea anemones or earthworms, have developed sophisticated virulence factors such as the pore-forming toxins (PFTs) to mount their attack against the host. One of the most fascinating aspects of PFTs is that they can adopt a water-soluble form at the begin...
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PMID: 18298943
PDF is available here.
PDF is available here.
Abstract
We reported that colicinogenic bacteria seemed beneficial in preventing the clinical manifestations of infectious disease caused by enterohemorrhagic E. coli O157 in humans. The inhibitory effects could be due to a decrease in O157 levels and/or pathogenicity. This study investigated the effects of...
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PMID: 17933918
PDF is available here.
PDF is available here.
BioTechniques (43)6 2007
Abstract
We have developed a novel vector pTCS, as a tool for efficient selection of open reading frame (ORF)-containing inserts. In pTCS clones containing an insert with an ORF a downstream marker gene (immE3, conferring resistance to colicin) is activated via translational coupling with the insert, and tra...
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PMID: 18251250
PDF is available here.
PDF is available here.
Abstract
We examined the efficacy of the dietary inclusion of colicin E1 in preventing experimentally induced PWD caused by F18-positive enterotoxigenic E. coli in young pigs. Twenty-four weaned pigs (23 days of age), identified by genotyping to be susceptible to F18-positive E. coli infections, were individ...
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PMID: 17724148
PDF is available here.
PDF is available here.
Journal of Biological Chemistry (282)43 2007
Abstract
We set out to test this hypothesis in vivo. We show that cell killing by the DNase toxin colicin E9 of E. coli HDL11, a strain in which the level of anionic phospholipid and hence inner membrane charge is regulated by isopropyl beta-D-thiogalactopyranoside induction, is critically dependent on the l...
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PMID: 17720814
PDF is available here.
PDF is available here.
FEBS Letters (581)25 2007
Abstract
We performed molecular dynamic simulations of two LexA dimers bound to operators. Our model predicted that rotation of the LexA DNA binding domain, with respect to the dimerised C-terminal domain, is required for selective DNA binding. To confirm the model, double and quadruple cysteine LexA mutants...
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PMID: 17884043
PDF is available here.
PDF is available here.
Journal of Bacteriology (189)19 2007
Abstract
Survey results and genotypic characterization of Escherichia coli strains demonstrate that the bacteriocins colicin Ia and microcin V coassociate in a strain more often than would be expected by chance. When these two bacteriocins co-occur, they are encoded on the same conjugative plasmid. Plasmids...
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PMID: 17644607
PDF is available here.
PDF is available here.
Microbiology (153)Pt 9 2007
Abstract
The production of antimicrobial compounds known as colicins has been shown to be an important mediator of competitive interactions among Escherichia coli genotypes. There is some understanding of the forces responsible for determining the frequency of colicin production in E. coli populations; howev...
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PMID: 17768227
PDF is available here.
PDF is available here.
Journal of Biological Chemistry (282)33 2007
Abstract
I fimbriae (CFA/I) of enterotoxigenic Escherichia coli and is thought to be essential for the attachment of enterotoxigenic E. coli to the human small intestine early in diarrhea pathogenesis. The crystal structure of an in cis donor strand complemented CfaE was determined, providing the first atomi...
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PMID: 17569668
PDF is available here.
PDF is available here.
Journal of Biological Chemistry (282)32 2007
Abstract
The crystal structure of the complex of the BtuB receptor and the 135-residue coiled-coil receptor-binding R-domain of colicin E3 (E3R135) suggested a novel mechanism for import of colicin proteins across the outer membrane. It was proposed that one function of the R-domain, which extends along the...
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PMID: 17548346
PDF is available here.
PDF is available here.
Abstract
We successfully constructed an expression vector pQE30-cfa-cfi producing high levels of His-tagged colicin 5 (60-80 mg/L). We found that the purified His-tagged colicin 5 possesses narrow-spectrum bactericidal activity against nonimmune Escherichia coli cells. It is highly toxic to sensitive E. coli...
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PMID: 17451967
PDF is available here.
PDF is available here.
Molecular Microbiology (65)2 2007
Abstract
We engineered cysteine (Cys) substitutions in the globular domain of FepA. Colicin B caused increased exposure to biotin maleimide labelling of all Cys substitutions, but to different degrees, with TonB as well as the FepA TonB box required for all increases. Because of the large increases in exposu...
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PMID: 17578453
PDF is available here.
PDF is available here.
Abstract
We concentrated on higher-molecular-mass microcins, i.e., those possessing 60 or more amino acids. They can be subdivided into unmodified and posttranslationally modified peptides. In both cases, they exhibit conserved C-terminal sequences that appear to be characteristic of each subgroup. In the hy...
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PMID: 17452478
PDF is available here.
PDF is available here.
Journal of Bacteriology (189)13 2007
Abstract
The active transport of iron siderophores and vitamin B(12) across the outer membrane (OM) of Escherichia coli requires OM transporters and the potential energy of the cytoplasmic membrane (CM) proton gradient and CM proteins TonB, ExbB, and ExbD. A region at the amino terminus of the transporter, c...
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PMID: 17483231
PDF is available here.
PDF is available here.
Abstract
We tested the efficacy of a killed oral vaccine for enterotoxigenic Escherichia coli (ETEC) diarrhoea to determine if two doses of vaccine with colonization factor antigens (CF) and cholera B subunit would protect against ETEC diarrhoea of travellers. Six hundred seventy-two healthy travellers going...
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PMID: 17448578
PDF is available here.
PDF is available here.
Journal of Bacteriology (189)11 2007
Abstract
I show that preincubation of ColE2 with Escherichia coli cells prevents binding and translocation of pore-forming colicins of group A but not of group B. This inhibition persisted even when cells were incubated with ColE2 for 30 min before the addition of pore-forming colicins, indicating that ColE2...
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PMID: 17416663
PDF is available here.
PDF is available here.
Biochemistry (Washington) (46)20 2007
Abstract
The membrane-bound closed state (zero potential) of the helix 3 segment (Lys-381-Ser-405) of the colicin E1 channel domain was investigated by site-directed fluorescence labeling using a bimane probe tethered to a single cysteine residue of each mutant protein. A number of fluorescen...
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PMID: 17455912
PDF is available here.
PDF is available here.
EMBO Journal (26)10 2007
Abstract
We determined crystal structures of colicin I receptor alone and in complex with the receptor binding domain of colicin Ia. The receptor undergoes large and unusual conformational changes upon colicin binding, opening at the cell surface and positioning the receptor binding domain of colicin Ia dire...
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PMID: 17464289
PDF is available here.
PDF is available here.
Journal of Molecular Biology (368)3 2007
Abstract
We studied a non-specific endonuclease, the nuclease domain of ColE7 (N-ColE7), to decipher the role of the conserved asparagine and histidine residues in the HNH motif. We found, using fluorescence resonance energy transfer (FRET) assays, that the DNA hydrolysis activity of H545 N-ColE7 mutants was...
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PMID: 17368670
PDF is available here.
PDF is available here.
Abstract
Colicins are gram-negative bacteriocins produced by and effective against Escherichia coli and related species. Colicin E1 (ColE1) is composed of three functional domains, which collectively have a pore-forming effect on targeted bacteria. ColE1 binding and translocation domains are highly specific...
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PMID: 17536690
PDF is available here.
PDF is available here.
Biophysical Journal (92)9 2007
Abstract
We describe the effect of complexation by the high affinity protein ligand E9 on the mechanical resistance of the simple four-helical protein, Im9. When concatenated into a construct of alternating I27 domains, Im9 unfolded below the thermal noise limit of the instrument ( approximately 20 pN). Comp...
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PMID: 17351013
PDF is available here.
PDF is available here.
Abstract
We show that W-band spectra are particularly useful for detection of anisotropy of spin label motion. On complex formation significant changes are observed in the dynamics of labels at the binding interface region. This work reveals multi-frequency EPR as a sensitive and valuable tool for detecting...
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PMID: 17218133
PDF is available here.
PDF is available here.
Infection and Immunity (75)4 2007
Abstract
We identified a six-gene cluster in chromosome 1 encoding a two-component regulatory system (BCAL2831 and BCAL2830) and an HtrA protease (BCAL2829) hypothesized to play a role in the B. cenocepacia stress response. Reverse transcriptase PCR analysis of these six genes confirmed they are cotranscribe...
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PMID: 17220310
PDF is available here.
PDF is available here.
Journal of Bacteriology (189)7 2007
Abstract
We studied the early events in the import of ColE1. Using in vivo approaches, we show that ColE1 is cleaved when added to whole cells. This cleavage requires the presence of the receptor BtuB and the protease OmpT, but not that of TolC. Strains expressing OmpT cleaved ColE1 at K84 and K95 in the N-t...
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PMID: 17277071
PDF is available here.
PDF is available here.
Journal of Molecular Biology (366)5 2007
Abstract
We used a model system involved in two different processes, one of which depends on inner membrane energy. The Tol machinery of the Escherichia coli cell envelope is dedicated to maintaining outer membrane stability, a process driven by the proton-motive force. The Tol system is parasitized by bacte...
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PMID: 17222427
PDF is available here.
PDF is available here.
Abstract
Colicins are proteins produced by and toxic for some strains of Escherichia coli. They are produced by strains of E. coli carrying a colicinogenic plasmid that bears the genetic determinants for colicin synthesis, immunity, and release. Insights gained into each fundamental aspect of their biology a...
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PMID: 17347522
PDF is available here.
PDF is available here.
Abstract
Abstract
Despite the critical role of plasmids in horizontal gene transfer, few studies have characterized plasmid relatedness among different bacterial populations. Recently, a multiplex PCR replicon typing protocol was developed for classification of plasmids occurring in members of the Enterobacteriaceae....
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PMID: 17277222
PDF is available here.
PDF is available here.
Abstract
Colicin K exhibited pronounced inhibitory activity against uropathogenic Escherichia coli (UPEC) strains. Low prevalence of colicin K production and a relatively high prevalence of ColE1-like plasmids were determined among 215 UPEC strains from Slovenia. Sequencing of the colicin K-encoding pColK-K2...
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PMID: 17122402
PDF is available here.
PDF is available here.