Ib-M6 Antimicrobial Peptide: Antibacterial Activity against Clinical Isolates of Escherichia coli and Molecular Docking

The Ib-M6 peptide has antibacterial activity against non-pathogenic Escherichia coli K-12 strain. The first part of this study determines the antibacterial activity of Ib-M6 against fourteen pathogenic strains of E. coli O157:H7. Susceptibility assay showed that Ib-M6 had values of Minimum Inhibitory Concentration (MIC) lower than streptomycin, used as a reference antibiotic. Moreover, to predict the possible interaction between Ib-M6 and outer membrane components of E. coli, we used molecular docking simulations where FhuA protein and its complex with Lipopolysaccharide (LPS–FhuA) were used as targets of the peptide. FhuA/Ib-M6 complexes had energy values between −39.5 and −40.5 Rosetta Energy Units (REU) and only one hydrogen bond. In contrast, complexes between LPS–FhuA and Ib-M6 displayed energy values between −25.6 and −40.6 REU, and the presence of five possible hydrogen bonds. Hence, the antimicrobial activity of Ib-M6 peptide shown in the experimental assays could be caused by its interaction with the outer membrane of E. coli.

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afa-8 Gene Cluster Is Carried by a Pathogenicity Island Inserted into the tRNAPhe of Human and Bovine Pathogenic Escherichia coli Isolates

Infection and Immunity ◽

10.1128/iai.69.2.937-948.2001 ◽

2001 ◽

Vol 69 (2) ◽

pp. 937-948 ◽

Cited By ~ 48

Author(s):

Lila Lalioui ◽

Chantal Le Bouguénec

Keyword(s):

Escherichia Coli ◽

Direct Repeat ◽

Pathogenicity Island ◽

Genomic Region ◽

Open Reading Frames ◽

Blood Isolate ◽

Distinctive Features ◽

E Coli ◽

Pathogenic Escherichia Coli ◽

K 12

ABSTRACT We recently described a new afimbrial adhesin, AfaE-VIII, produced by animal strains associated with diarrhea and septicemia and by human isolates associated with extraintestinal infections. Here, we report that the afa-8 operon, encoding AfaE-VIII adhesin, from the human blood isolate Escherichia coli AL862 is carried by a 61-kb genomic region with characteristics typical of a pathogenicity island (PAI), including a size larger than 10 kb, the presence of an integrase-encoding gene, the insertion into a tRNA locus (pheR), and the presence of a small direct repeat at each extremity. Moreover, the G+C content of the afa-8 operon (46.4%) is lower than that of the E. coli K-12/MG1655 chromosome (50.8%). Within this PAI, designated PAI IAL862, we identified open reading frames able to code for products similar to proteins involved in sugar utilization. Four probes spanning these sequences hybridized with 74.3% of pathogenicafa-8-positive E. coli strains isolated from humans and animals, 25% of human pathogenic afa-8-negativeE. coli strains, and only 8% of fecal strains (P = 0.05), indicating that these sequences are strongly associated with the afa-8 operon and that this genetic association may define a PAI widely distributed among human and animal afa-8-positive strains. One of the distinctive features of this study is that E. coli AL862 also carries another afa-8-containing PAI (PAI IIAL862), which appeared to be similar in size and genetic organization to PAI IAL862 and was inserted into the pheV gene. We investigated the insertion sites of afa-8-containing PAI in human and bovine pathogenic E. coli strains and found that this PAI preferentially inserted into the pheV gene.

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The c-Type Cytochrome OmcA Localizes to the Outer Membrane upon Heterologous Expression in Escherichia coli

Journal of Bacteriology ◽

10.1128/jb.00395-08 ◽

2008 ◽

Vol 190 (14) ◽

pp. 5127-5131 ◽

Cited By ~ 18

Author(s):

James W. Donald ◽

Matthew G. Hicks ◽

David J. Richardson ◽

Tracy Palmer

Keyword(s):

Escherichia Coli ◽

Outer Membrane ◽

Shewanella Oneidensis ◽

Type Ii Secretion ◽

Type Ii ◽

E Coli ◽

Expression In Escherichia Coli ◽

Type Ii Secretion System ◽

Surface Localization ◽

K 12

ABSTRACT We have functionally produced the outer membrane cytochrome OmcA from Shewanella oneidensis in Escherichia coli. Substrate accessibility experiments indicate that OmcA is surface exposed in an E. coli B strain but not in a K-12 strain. We show that a functional type II secretion system is required for surface localization.

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Envelope alteration of Escherichia coli HB101 carrying pEAP31 caused by Kil peptide and its involvement in the extracellular release of periplasmic penicillinase from an alkaliphilic Bacillus

Biochemical Journal ◽

10.1042/bj2750545 ◽

1991 ◽

Vol 275 (3) ◽

pp. 545-553 ◽

Cited By ~ 3

Author(s):

R Aono

Keyword(s):

Escherichia Coli ◽

Stationary Phase ◽

Outer Membrane ◽

E Coli ◽

Colicin E1 ◽

Extracellular Release ◽

Periplasmic Proteins ◽

Alkaliphilic Bacillus ◽

Membrane Components

The plasmid pEAP31 contains the colicin E1 kil gene. Peptidoglycan and outer-membrane components (lipopoly-saccharide, proteins and phosphatidylethanolamine) decreased concurrently in the envelope fraction from Escherichia coli HB101 carrying pEAP31 during the stationary phase of growth. At almost the same time. D-alanine residues in peptidoglycan decreased. The Kil peptide is suggested to affect, directly or indirectly, the turnover of peptidoglycan in stationary phase and, as a result, to cause partial exfoliation of the outer membrane. Periplasmic proteins are liberated from E. coli HB101 (pEAP31) probably because of the exfoliation of outer membrane.

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Some Characteristics of the Outer Membrane Material Released by Growing Enterotoxigenic Escherichia coli

Infection and Immunity ◽

10.1128/iai.29.2.704-713.1980 ◽

1980 ◽

Vol 29 (2) ◽

pp. 704-713 ◽

Cited By ~ 1

Author(s):

Henk Gankema ◽

Jan Wensink ◽

Pieter A. M. Guinée ◽

Wim H. Jansen ◽

Bernard Witholt

Keyword(s):

Escherichia Coli ◽

Outer Membrane ◽

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

Freeze Fracture ◽

Sucrose Density Gradient ◽

Enterotoxigenic Escherichia Coli ◽

E Coli ◽

Freeze Fracture Electron Microscopy ◽

K 12

The high-molecular-weight material released into the medium by Escherichia coli AP1, an enterotoxigenic strain of porcine origin, has been isolated and resolved into two clearly distinct fractions, based on sucrose density gradient and differential centrifugation, chemical analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and freeze-fracture electron microscopy. These two fractions, referred to as “medium vesicles” and “medium lipopolysaccharides”, were compared with the cellular outer and cytoplasmic membranes, the periplasmic fraction, and the cytoplasmic fraction. The medium vesicles closely resembled outer membrane and accounted for 3 to 5% of the total cellular outer membrane. They contained most of the heat-labile enterotoxin (LT) activity released into the medium by E. coli AP1. The medium lipopolysaccharide consisted mostly of lipopolysaccharide and a small amount of outer membrane and contained relatively little LT activity. Based on experiments with E. coli K-12 strains, in which about 5% of the newly synthesized outer membrane is lost from areas of outer membrane synthesis, it is proposed that enterotoxigenic E. coli strains release LT as part of such newly synthesized outer membrane fragments and that released outer membrane fragments may function as physiologically significant LT carriers.

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O-Antigen-Dependent Colicin Insensitivity of UropathogenicEscherichia coli

Journal of Bacteriology ◽

10.1128/jb.00545-18 ◽

2018 ◽

Vol 201 (4) ◽

Cited By ~ 12

Author(s):

Connor Sharp ◽

Christine Boinett ◽

Amy Cain ◽

Nicholas G. Housden ◽

Sandip Kumar ◽

...

Keyword(s):

Escherichia Coli ◽

Outer Membrane ◽

Growth Conditions ◽

Membrane Receptors ◽

Cell Surface Receptor ◽

Dominant Factor ◽

Content Type ◽

E Coli ◽

O Antigen ◽

K 12

ABSTRACTThe outer membrane of Gram-negative bacteria presents a significant barrier for molecules entering the cell. Nevertheless, colicins, which are antimicrobial proteins secreted byEscherichia coli, can target otherE. colicells by binding to cell surface receptor proteins and activating their import, resulting in cell death. Previous studies have documented high rates of nonspecific resistance (insensitivity) of variousE. colistrains toward colicins that is independent of colicin-specific immunity and is instead associated with lipopolysaccharide (LPS) in the outer membrane. This observation poses a contradiction: why doE. colistrains have colicin-expressing plasmids, which are energetically costly to retain, if cells around them are likely to be naturally insensitive to the colicin they produce? Here, using a combination of transposon sequencing and phenotypic microarrays, we show that colicin insensitivity of uropathogenicE. colisequence type 131 (ST131) is dependent on the production of its O-antigen but that minor changes in growth conditions render the organism sensitive toward colicins. The reintroduction of O-antigen intoE. coliK-12 demonstrated that it is the density of O-antigen that is the dominant factor governing colicin insensitivity. We also show, by microscopy of fluorescently labelled colicins, that growth conditions affect the degree of occlusion by O-antigen of outer membrane receptors but not the clustered organization of receptors. The result of our study demonstrate that environmental conditions play a critical role in sensitizingE. colitoward colicins and that O-antigen in LPS is central to this role.IMPORTANCEEscherichia coliinfections can be a major health burden, especially with the organism becoming increasingly resistant to “last-resort” antibiotics such as carbapenems. Although colicins are potent narrow-spectrum antimicrobials with potential as future antibiotics, high levels of naturally occurring colicin insensitivity have been documented which could limit their efficacy. We identify O-antigen-dependent colicin insensitivity in a clinically relevant uropathogenicE. colistrain and show that this insensitivity can be circumvented by minor changes to growth conditions. The results of our study suggest that colicin insensitivity amongE. coliorganisms has been greatly overestimated, and as a consequence, colicins could in fact be effective species-specific antimicrobials targeting pathogenicE. colisuch as uropathogenicE. coli(UPEC).

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Flocculation of Escherichia coli Cells in Association with Enhanced Production of Outer Membrane Vesicles

Applied and Environmental Microbiology ◽

10.1128/aem.01011-15 ◽

2015 ◽

Vol 81 (17) ◽

pp. 5900-5906 ◽

Cited By ~ 9

Author(s):

Yoshihiro Ojima ◽

Minh Hong Nguyen ◽

Reiki Yajima ◽

Masahito Taya

Keyword(s):

Escherichia Coli ◽

Outer Membrane ◽

Sodium Dodecyl ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Laser Scanning Microscopy ◽

Content Type ◽

E Coli ◽

Enhanced Production ◽

K 12

ABSTRACTMicrobial flocculation is a phenomenon of aggregation of dispersed bacterial cells in the form of flocs or flakes. In this study, the mechanism of spontaneous flocculation ofEscherichia colicells by overexpression of thebcsBgene was investigated. The flocculation induced by overexpression ofbcsBwas consistent among the variousE. colistrains examined, including the K-12, B, and O strains, with flocs that resembled paper scraps in structure being about 1 to 2 mm. The distribution of green fluorescent protein-labeledE. colicells within the floc structure was investigated by three-dimensional confocal laser scanning microscopy. Flocs were sensitive to proteinase K, indicating that the main component of the flocs was proteinous. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and nano-liquid chromatography tandem mass spectrometry analyses of the flocs strongly suggested the involvement of outer membrane vesicles (OMVs) inE. coliflocculation. The involvement of OMVs in flocculation was supported by transmission electron microscopy observation of flocs. Furthermore,bcsB-inducedE. coliflocculation was greatly suppressed in strains with hypovesiculation phenotypes (ΔdsbAand ΔdsbBstrains). Thus, our results demonstrate the strong correlation between spontaneous flocculation and enhanced OMV production ofE. colicells.

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Properties of haemolysin E (HlyE) from a pathogenic Escherichia coli avian isolate and studies of HlyE export

Microbiology ◽

10.1099/mic.0.26877-0 ◽

2004 ◽

Vol 150 (5) ◽

pp. 1495-1505 ◽

Cited By ~ 19

Author(s):

Neil R. Wyborn ◽

Angela Clark ◽

Ruth E. Roberts ◽

Stuart J. Jamieson ◽

Svetomir Tzokov ◽

...

Keyword(s):

Escherichia Coli ◽

Blood Cells ◽

Cell Envelope ◽

Membrane Integrity ◽

Intrinsic Property ◽

E Coli ◽

Pathogenic Escherichia Coli ◽

Carboxyl Terminal ◽

K 12

Haemolysin E (HlyE) is a novel pore-forming toxin first identified in Escherichia coli K-12. Analysis of the 3-D structure of HlyE led to the proposal that a unique hydrophobic β-hairpin structure (the β-tongue, residues 177–203) interacts with the lipid bilayer in target membranes. In seeming contradiction to this, the hlyE sequence from a pathogenic E. coli strain (JM4660) that lacks all other haemolysins has been reported to encode an Arg residue at position 188 that was difficult to reconcile with the proposed role of the β-tongue. Here it is shown that the JM4660 hlyE sequence encodes Gly, not Arg, at position 188 and that substitution of Gly188 by Arg in E. coli K-12 HlyE abolishes activity, emphasizing the importance of the head domain in HlyE function. Nevertheless, 76 other amino acid substitutions were confirmed compared to the HlyE protein of E. coli K-12. The JM4660 HlyE protein was dimeric, suggesting a mechanism for improving toxin solubility, and it lysed red blood cells from many species by forming 36–41 Å diameter pores. However, the haemolytic phenotype of JM4660 was found to be unstable due to defects in HlyE export, indicating that export of active HlyE is not an intrinsic property of the protein but requires additional components. TnphoA mutagenesis of hlyE shows that secretion from the cytoplasm to the periplasm does not require the carboxyl-terminal region of HlyE. Finally, disruption of genes associated with cell envelope function, including tatC, impairs HlyE export, indicating that outer membrane integrity is important for effective HlyE secretion.

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Compilation of Escherichia coli K-12 outer membrane phage receptors – their function and some historical remarks

FEMS Microbiology Letters ◽

10.1093/femsle/fnaa013 ◽

2020 ◽

Vol 367 (2) ◽

Cited By ~ 2

Author(s):

Klaus Hantke

Keyword(s):

Escherichia Coli ◽

Outer Membrane ◽

Outer Membrane Proteins ◽

Functional Characterization ◽

Historical Context ◽

E Coli ◽

Great Progress ◽

Historical Remarks ◽

K 12 ◽

Made In

ABSTRACT Many Escherichia coli phages have been sequenced, but in most cases their sequences alone do not suffice to predict their host specificity. Analysis of phage resistant E. coli K-12 mutants have uncovered a certain set of outer membrane proteins and polysaccharides as receptors. In this review, a compilation of E. coli K12 phage receptors is provided and their functional characterization, often driven by studies on phage resistant mutants, is discussed in the historical context. While great progress has been made in this field thus far, several proteins in the outer membrane still await characterization as phage receptors.

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Characterization of a Novel Two-Partner Secretion System in Escherichia coli O157:H7

Journal of Bacteriology ◽

10.1128/jb.01751-06 ◽

2007 ◽

Vol 189 (9) ◽

pp. 3452-3461 ◽

Cited By ~ 11

Author(s):

Peter S. Choi ◽

Ashley J. Dawson ◽

Harris D. Bernstein

Keyword(s):

Escherichia Coli ◽

Outer Membrane ◽

Direct Evidence ◽

E Coli ◽

Essential Components ◽

Bona Fide ◽

Secretion Pathways ◽

K 12 ◽

Extracellular Environment

ABSTRACT Gram-negative bacteria contain multiple secretion pathways that facilitate the translocation of proteins across the outer membrane. The two-partner secretion (TPS) system is composed of two essential components, a secreted exoprotein and a pore-forming β barrel protein that is thought to transport the exoprotein across the outer membrane. A putative TPS system was previously described in the annotation of the genome of Escherichia coli O157:H7 strain EDL933. We found that the two components of this system, which we designate OtpA and OtpB, are not predicted to belong to either of the two major subtypes of TPS systems (hemolysins and adhesins) based on their sequences. Nevertheless, we obtained direct evidence that OtpA and OtpB constitute a bona fide TPS system. We found that secretion of OtpA into the extracellular environment in E. coli O157:H7 requires OtpB and that when OtpA was produced in an E. coli K-12 strain, its secretion was strictly dependent on the production of OtpB. Furthermore, using OtpA/OtpB as a model system, we show that protein secretion via the TPS pathway is extremely rapid.

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Reciprocal Packaging of the Main Structural Proteins of Type 1 Fimbriae and Flagella in the Outer Membrane Vesicles of “Wild Type” Escherichia coli Strains

Frontiers in Microbiology ◽

10.3389/fmicb.2021.557455 ◽

2021 ◽

Vol 12 ◽

Author(s):

Sarah A. Blackburn ◽

Mark Shepherd ◽

Gary K. Robinson

Keyword(s):

Escherichia Coli ◽

Outer Membrane ◽

Membrane Vesicle ◽

Outer Membrane Vesicles ◽

Wild Type ◽

Protein Fusion ◽

E Coli ◽

Type 1 Fimbriae ◽

K 12

Fundamental aspects of outer membrane vesicle (OMV) biogenesis and the engineering of producer strains have been major research foci for many in recent years. The focus of this study was OMV production in a variety of Escherichia coli strains including wild type (WT) (K12 and BW25113), mutants (from the Keio collection) and proprietary [BL21 and BL21 (DE3)] strains. The present study investigated the proteome and prospective mechanism that underpinned the key finding that the dominant protein present in E. coli K-12 WT OMVs was fimbrial protein monomer (FimA) (a polymerizable protein which is the key structural monomer from which Type 1 fimbriae are made). However, mutations in genes involved in fimbriae biosynthesis (ΔfimA, B, C, and F) resulted in the packaging of flagella protein monomer (FliC) (the major structural protein of flagella) into OMVs instead of FimA. Other mutations (ΔfimE, G, H, I, and ΔlrhA–a transcriptional regulator of fimbriation and flagella biosynthesis) lead to the packaging of both FimA and Flagellin into the OMVs. In the majority of instances shown within this research, the production of OMVs is considered in K-12 WT strains where structural appendages including fimbriae or flagella are temporally co-expressed throughout the growth curve as shown previously in the literature. The hypothesis, proposed and supported within the present paper, is that the vesicular packaging of the major FimA is reciprocally regulated with the major FliC in E. coli K-12 OMVs but this is abrogated in a range of mutated, non-WT E. coli strains. We also demonstrate, that a protein of interest (GFP) can be targeted to OMVs in an E. coli K-12 strain by protein fusion with FimA and that this causes normal packaging to be disrupted. The findings and underlying implications for host interactions and use in biotechnology are discussed.

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