scholarly journals Identification of an Escherichia coli Operon Required for Formation of the O-Antigen Capsule

2005 ◽  
Vol 187 (15) ◽  
pp. 5259-5266 ◽  
Author(s):  
Adi Peleg ◽  
Yulia Shifrin ◽  
Ophir Ilan ◽  
Chen Nadler-Yona ◽  
Shani Nov ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Secretion System ◽  
Side Chain ◽  
E Coli ◽  
O Antigen ◽  
Group 4 ◽  
K 12 ◽  
Polysaccharide Capsules ◽  
Polysaccharide Secretion ◽  
Group 1

ABSTRACT Escherichia coli produces polysaccharide capsules that, based on their mechanisms of synthesis and assembly, have been classified into four groups. The group 4 capsule (G4C) polysaccharide is frequently identical to that of the cognate lipopolysaccharide O side chain and has, therefore, also been termed the O-antigen capsule. The genes involved in the assembly of the group 1, 2, and 3 capsules have been described, but those required for G4C assembly remained obscure. We found that enteropathogenic E. coli (EPEC) produces G4C, and we identified an operon containing seven genes, ymcD, ymcC, ymcB, ymcA, yccZ, etp, and etk, which are required for formation of the capsule. The encoded proteins appear to constitute a polysaccharide secretion system. The G4C operon is absent from the genomes of enteroaggregative E. coli and uropathogenic E. coli. E. coli K-12 contains the G4C operon but does not express it, because of the presence of IS1 at its promoter region. In contrast, EPEC, enterohemorrhagic E. coli, and Shigella species possess an intact G4C operon.

scholarly journals Bioinformatic and Molecular Analysis of Inverse Autotransporters from Escherichia coli

mSphere ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Kelvin G. K. Goh ◽  
Danilo G. Moriel ◽  
Steven J. Hancock ◽  
Minh-Duy Phan ◽  
Mark A. Schembri
Keyword(s):  
Escherichia Coli ◽  
Cell Surface ◽  
Biofilm Formation ◽  
Secretion System ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Type V Secretion ◽  
K 12 ◽  
Type V

ABSTRACT Proteins secreted by the type V secretion system possess multiple functions, including the capacity to mediate adhesion, aggregation, and biolfilm formation. The type V secretion system can be divided into five subclasses, one of which is the type Ve system. Proteins of the type Ve secretion system are also referred to as inverse autotransporters (IATs). In this study, we performed an in silico analysis of 126 completely sequenced Escherichia coli genomes available in the NCBI database and identified several distinct IAT-encoding gene families whose distribution varied throughout the E. coli phylogeny. The genes included three characterized IATs (intimin, fdeC, and yeeJ) and four uncharacterized IATs (here named iatA, iatB, iatC, and iatD). The four iat genes were cloned from the completely sequenced environmental E. coli strain SMS-3-5 and characterized. Three of these IAT proteins (IatB, IatC, and IatD) were expressed at the cell surface and possessed the capacity to mediate biofilm formation in a recombinant E. coli K-12 strain. Further analysis of the iatB gene, which showed a unique association with extraintestinal E. coli strains, suggested that its regulation is controlled by the LeuO global regulator. Overall, this study provides new data describing the prevalence, sequence variation, domain structure, function, and regulation of IATs found in E. coli. IMPORTANCE Escherichia coli is one of the most prevalent facultative anaerobes of the human gut. E. coli normally exists as a harmless commensal but can also cause disease following the acquisition of genes that enhance its pathogenicity. Adhesion is an important first step in colonization of the host and is mediated by an array of cell surface components. In E. coli, these include a family of adhesins secreted by the type V secretion system. Here, we identified and characterized new proteins from an emerging subclass of the type V secretion system known as the inverse autotransporters (IATs). We found that IAT-encoding genes are present in a wide range of strains and showed that three novel IATs were localized on the E. coli cell surface and mediated biofilm formation. Overall, this study provides new insight into the prevalence, function, and regulation of IATs in E. coli.

scholarly journals Variations in O-Antigen Biosynthesis and O-Acetylation Associated with Altered Phage Sensitivity in Escherichia coli 4s

2014 ◽  
Vol 197 (5) ◽  
pp. 905-912 ◽  
Author(s):  
Yuriy A. Knirel ◽  
Nikolai S. Prokhorov ◽  
Alexander S. Shashkov ◽  
Olga G. Ovchinnikova ◽  
Evelina L. Zdorovenko ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Host Cells ◽  
Side Chain ◽  
Gram Negative Bacteria ◽  
Gene Encoding ◽  
Content Type ◽  
Surface Receptors ◽  
E Coli ◽  
O Antigen ◽  
Phage Sensitivity

The O polysaccharide of the lipopolysaccharide (O antigen) of Gram-negative bacteria often serves as a receptor for bacteriophages that can make the phage dependent on a given O-antigen type, thus supporting the concept of the adaptive significance of the O-antigen variability in bacteria. The O-antigen layer also modulates interactions of many bacteriophages with their hosts, limiting the access of the viruses to other cell surface receptors. Here we report variations of O-antigen synthesis and structure in an environmentalEscherichia coliisolate, 4s, obtained from horse feces, and its mutants selected for resistance to bacteriophage G7C, isolated from the same fecal sample. The 4s O antigen was found to be serologically, structurally, and genetically related to the O antigen ofE. coliO22, differing only in side-chain α-d-glucosylation in the former, mediated by agtrlocus on the chromosome. Spontaneous mutations ofE. coli4s occurring with an unusually high frequency affected either O-antigen synthesis or O-acetylation due to the inactivation of the gene encoding the putative glycosyltransferase WclH or the putative acetyltransferase WclK, respectively, by the insertion of IS1-like elements. These mutations induced resistance to bacteriophage G7C and also modified interactions ofE. coli4s with several other bacteriophages conferring either resistance or sensitivity to the host. These findings suggest that O-antigen synthesis and O-acetylation can both ensure the specific recognition of the O-antigen receptor following infection by some phages and provide protection of the host cells against attack by other phages.

scholarly journals O-Antigen-Dependent Colicin Insensitivity of UropathogenicEscherichia coli

2018 ◽  
Vol 201 (4) ◽  
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).

scholarly journals The lipopolysaccharide of the mastitis isolate Escherichia coli strain 1303 comprises a novel O-antigen and the rare K-12 core type

Microbiology ◽  
2011 ◽  
Vol 157 (6) ◽  
pp. 1750-1760 ◽  
Author(s):  
Katarzyna A. Duda ◽  
Buko Lindner ◽  
Helmut Brade ◽  
Andreas Leimbach ◽  
Elżbieta Brzuszkiewicz ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Inner Core ◽  
Bovine Mastitis ◽  
Outer Core ◽  
Coli Strain ◽  
Core Oligosaccharide ◽  
2D Nmr Spectroscopy ◽  
E Coli ◽  
O Antigen ◽  
K 12

Mastitis represents one of the most significant health problems of dairy herds. The two major causative agents of this disease are Escherichia coli and Staphylococcus aureus. Of the first, its lipopolysaccharide (LPS) is thought to play a prominent role during infection. Here, we report the O-antigen (OPS, O-specific polysaccharide) structure of the LPS from bovine mastitis isolate E. coli 1303. The structure was determined utilizing chemical analyses, mass spectrometry, and 1D and 2D NMR spectroscopy methods. The O-repeating unit was characterized as -[→4)-β-d-Quip3NAc-(1→3)-α-l-Fucp2OAc-(1→4)-β-d-Galp-(1→3)-α-d-GalpNAc-(1→]- in which the O-acetyl substitution was non-stoichiometric. The nucleotide sequence of the O-antigen gene cluster of E. coli 1303 was also determined. This cluster, located between the gnd and galF genes, contains 13 putative open reading frames, most of which represent unknown nucleotide sequences that have not been described before. The O-antigen of E. coli 1303 was shown to substitute O-7 of the terminal ld-heptose of the K-12 core oligosaccharide. Interestingly, the non-OPS-substituted core oligosaccharide represented a truncated version of the K-12 outer core – namely terminal ld-heptose and glucose were missing; however, it possessed a third Kdo residue in the inner core. On the basis of structural and genetic data we show that the mastitis isolate E. coli 1303 represents a new serotype and possesses the K-12 core type, which is rather uncommon among human and bovine isolates.

scholarly journals The ETT2 Gene Cluster, Encoding a Second Type III Secretion System from Escherichia coli, Is Present in the Majority of Strains but Has Undergone Widespread Mutational Attrition

2004 ◽  
Vol 186 (11) ◽  
pp. 3547-3560 ◽  
Author(s):  
Chuan-Peng Ren ◽  
Roy R. Chaudhuri ◽  
Amanda Fivian ◽  
Christopher M. Bailey ◽  
Martin Antonio ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Genome Sequences ◽  
Phylogenetic Structure ◽  
E Coli ◽  
Type Iii ◽  
K 12

ABSTRACT ETT2 is a second cryptic type III secretion system in Escherichia coli which was first discovered through the analysis of genome sequences of enterohemorrhagic E. coli O157:H7. Comparative analyses of Escherichia and Shigella genome sequences revealed that the ETT2 gene cluster is larger than was previously thought, encompassing homologues of genes from the Spi-1, Spi-2, and Spi-3 Salmonella pathogenicity islands. ETT2-associated genes, including regulators and chaperones, were found at the same chromosomal location in the majority of genome-sequenced strains, including the laboratory strain K-12. Using a PCR-based approach, we constructed a complete tiling path through the ETT2 gene cluster for 79 strains, including the well-characterized E. coli reference collection supplemented with additional pathotypes. The ETT2 gene cluster was found to be present in whole or in part in the majority of E. coli strains, whether pathogenic or commensal, with patterns of distribution and deletion mirroring the known phylogenetic structure of the species. In almost all strains, including enterohemorrhagic E. coli O157:H7, ETT2 has been subjected to varying degrees of mutational attrition that render it unable to encode a functioning secretion system. A second type III secretion system-associated locus that likely encodes the ETT2 translocation apparatus was found in some E. coli strains. Intact versions of both ETT2-related clusters are apparently present in enteroaggregative E. coli strain O42.

scholarly journals Functional Analysis of Conserved Gene Products Involved in Assembly of Escherichia coli Capsules and Exopolysaccharides: Evidence for Molecular Recognition between Wza and Wzc for Colanic Acid Biosynthesis

2005 ◽  
Vol 187 (15) ◽  
pp. 5470-5481 ◽  
Author(s):  
Anne N. Reid ◽  
Chris Whitfield
Keyword(s):  
Escherichia Coli ◽  
Chimeric Protein ◽  
Surface Expression ◽  
Capsular Polysaccharides ◽  
E Coli ◽  
Colanic Acid ◽  
Periplasmic Domain ◽  
Conserved Gene ◽  
K 12 ◽  
Group 1

ABSTRACT Group 1 capsular polysaccharides (CPSs) of Escherichia coli and some loosely cell-associated exopolysaccharides (EPSs), such as colanic acid, are assembled by a Wzy-dependent polymerization system. In this biosynthesis pathway, Wza, Wzb, and Wzc homologues are required for surface expression of wild-type CPS or EPS. Multimeric complexes of Wza in the outer membrane are believed to provide a channel for polymer export; Wzc is an inner membrane tyrosine autokinase and Wzb is its cognate phosphatase. This study was performed to determine whether the Wza, Wzb, and Wzc proteins for colanic acid expression in E. coli K-12 could function in the E. coli K30 prototype group 1 capsule system. When expressed together, colanic acid Wza, Wzb, and Wzc could complement a wza-wzb-wzc defect in E. coli K30, suggesting conservation in their collective function in Wzy-dependent CPS and EPS systems. Expressed individually, colanic acid Wza and Wzb could also function in K30 CPS expression. In contrast, the structural requirements for Wzc function were more stringent because colanic acid Wzc could restore translocation of K30 CPS to the cell surface only when expressed with its cognate Wza protein. Chimeric colanic acid-K30 Wzc proteins were constructed to further study this interaction. These proteins could restore K30 biosynthesis but were unable to couple synthesis to export. The chimeric protein comprising the periplasmic domain of colanic acid Wzc was functional for effective K30 CPS surface expression only when coexpressed with colanic acid Wza. These data highlight the importance of Wza-Wzc interactions in group 1 CPS assembly.

scholarly journals Defective O-Antigen Polymerization in tolA and pal Mutants of Escherichia coli in Response to Extracytoplasmic Stress

2005 ◽  
Vol 187 (10) ◽  
pp. 3359-3368 ◽  
Author(s):  
Enrique D. Vinés ◽  
Cristina L. Marolda ◽  
Aran Balachandran ◽  
Miguel A. Valvano
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Stress Responses ◽  
Surface Expression ◽  
Dependent Manner ◽  
E Coli ◽  
O Antigen ◽  
O Antigens ◽  
K 12 ◽  
Reduced Surface

ABSTRACT We have previously shown that the TolA protein is required for the correct surface expression of the Escherichia coli O7 antigen lipopolysaccharide (LPS). In this work, ΔtolA and Δpal mutants of E. coli K-12 W3110 were transformed with pMF19 (encoding a rhamnosyltransferase that reconstitutes the expression of O16-specific LPS), pWQ5 (encoding the Klebsiella pneumoniae O1 LPS gene cluster), or pWQ802 (encoding the genes necessary for the synthesis of Salmonella enterica O:54). Both ΔtolA and Δpal mutants exhibited reduced surface expression of O16 LPS as compared to parental W3110, but no significant differences were observed in the expression of K. pneumoniae O1 LPS and S. enterica O:54 LPS. Therefore, TolA and Pal are required for the correct surface expression of O antigens that are assembled in a wzy (polymerase)-dependent manner (like those of E. coli O7 and O16) but not for O antigens assembled by wzy-independent pathways (like K. pneumoniae O1 and S. enterica O:54). Furthermore, we show that the reduced surface expression of O16 LPS in ΔtolA and Δpal mutants was associated with a partial defect in O-antigen polymerization and it was corrected by complementation with intact tolA and pal genes, respectively. Using derivatives of W3110ΔtolA and W3110Δpal containing lacZ reporter fusions to fkpA and degP, we also demonstrate that the RpoE-mediated extracytoplasmic stress response is upregulated in these mutants. Moreover, an altered O16 polymerization was also detected under conditions that stimulate RpoE-mediated extracytoplasmic stress responses in tol + and pal + genetic backgrounds. A Wzy derivative with an epitope tag at the C-terminal end of the protein was stable in all the mutants, ruling out stress-mediated proteolysis of Wzy. We conclude that the absence of TolA and Pal elicits a sustained extracytoplasmic stress response that in turn reduces O-antigen polymerization but does not affect the stability of the Wzy O-antigen polymerase.

scholarly journals The Core Lipopolysaccharide of Escherichia coli Is a Ligand for the Dendritic-Cell-Specific Intercellular Adhesion Molecule Nonintegrin CD209 Receptor

2005 ◽  
Vol 187 (5) ◽  
pp. 1710-1715 ◽  
Author(s):  
John Klena ◽  
Pei Zhang ◽  
Olivier Schwartz ◽  
Sheila Hull ◽  
Tie Chen
Keyword(s):  
Escherichia Coli ◽  
Dendritic Cell ◽  
Adhesion Molecule ◽  
Intercellular Adhesion ◽  
Host Cells ◽  
Intercellular Adhesion Molecule ◽  
E Coli ◽  
O Antigen ◽  
K 12 ◽  
Rough Mutant

ABSTRACT The dendritic-cell-specific intercellular adhesion molecule nonintegrin (DC-SIGN) CD209 is a receptor for Escherichia coli K-12 that promotes bacterial adherence and phagocytosis. However, the ligand of E. coli for DC-SIGN has not yet been identified. In this study, we found that DC-SIGN did not mediate the phagocytosis of several pathogenic strains of E. coli, including enteropathogenic E. coli, enterohemorrhagic E. coli, enterotoxigenic E. coli, and uropathogenic E. coli, in dendritic cells or HeLa cells expressing human DC-SIGN antigen. However, we showed that an outer core lipopolysaccharide (LPS) (rough) mutant, unlike an inner core LPS (deep rough) mutant or O-antigen-expressing recombinant of E. coli K-12 was phagocytosed. These results demonstrate that the host cells expressing DC-SIGN can phagocytose E. coli in part by interacting with the complete core region of the LPS molecule. These results provide a mechanism for how O antigen acts as an antiphagocytic factor.

scholarly journals Structural genes for nitrate-inducible formate dehydrogenase in Escherichia coli K-12.

Genetics ◽  
1990 ◽  
Vol 125 (4) ◽  
pp. 691-702 ◽  
Author(s):  
B L Berg ◽  
V Stewart
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Formate Dehydrogenase ◽  
Recombinant Dna ◽  
Structural Genes ◽  
Respiratory Pathway ◽  
E Coli ◽  
Formate Oxidation ◽  
Operon Expression ◽  
K 12

Abstract Formate oxidation coupled to nitrate reduction constitutes a major anaerobic respiratory pathway in Escherichia coli. This respiratory chain consists of formate dehydrogenase-N, quinone, and nitrate reductase. We have isolated a recombinant DNA clone that likely contains the structural genes, fdnGHI, for the three subunits of formate dehydrogenase-N. The fdnGHI clone produced proteins of 110, 32 and 20 kDa which correspond to the subunit sizes of purified formate dehydrogenase-N. Our analysis indicates that fdnGHI is organized as an operon. We mapped the fdn operon to 32 min on the E. coli genetic map, close to the genes for cryptic nitrate reductase (encoded by the narZ operon). Expression of phi(fdnG-lacZ) operon fusions was induced by anaerobiosis and nitrate. This induction required fnr+ and narL+, two regulatory genes whose products are also required for the anaerobic, nitrate-inducible activation of the nitrate reductase structural gene operon, narGHJI. We conclude that regulation of fdnGHI and narGHJI expression is mediated through common pathways.

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