Search results for "(Escherichia coli)"
showing 10 items of 689 documents
Binding of Escherichia coli hemolysin and activation of the target cells is not receptor-dependent.
2005
Abstract Production of a single cysteine substitution mutant, S177C, allowed Escherichia coli hemolysin (HlyA) to be radioactively labeled with tritiated N-ethylmaleimide without affecting biological activity. It thus became possible to study the binding characteristics of HlyA as well as of toxin mutants in which one or both acylation sites were deleted. All toxins bound to erythrocytes and granulocytes in a nonsaturable manner. Only wild-type toxin and the lytic monoacylated mutant stimulated production of superoxide anions in granulocytes. An oxidative burst coincided with elevation of intracellular Ca2+, which was likely because of passive influx of Ca2+ through the toxin pores. Competi…
Oligomerization and hemolytic properties of the C-terminal domain of pyolysin, a cholesterol-dependent cytolysin
2013
Pyolysin (PLO) belongs to the homologous family of the cholesterol- dependent cytolysins (CDCs), which bind to cell membranes containing cholesterol to form oligomeric pores of large size. The CDC monomer structure consists of 4 domains. Among these, the C-terminal domain 4 has been implicated in membrane binding of the monomer, while the subsequent processes of oligomerization and membrane insertion have primarily been assigned to other domains of the molecule. Recombinantly expressed or proteolytic fragments that span domain 4 of the CDCs streptolysin O and perfringolysin O bind to membranes but fail to oligomerize, and they inhibit the activity of the respective wild-type toxins. We repo…
Expression of Active Streptolysin O in Escherichia coli as a Maltose-Binding-Protein-Streptolysin-O Fusion Protein. The N-Terminal 70 Amino Acids are…
1996
Streptolysin 0 (SLO) is the prototype of a family of cytolysins that consists of proteins which bind to cholesterol and form very large transmembrane pores. Structure/function studies on the pore-forming cytolysin SLO have been complicated by the proteolytic inactivation of a substantial portion of recombinant SLO (rSLO) expressed in Escherichia coli. To overcome this problem, translational fusions between the E. coli maltose-binding protein (MBP) gene and SLO were constructed, using the vectors pMAL-p2 and pMAL-c2. MBP-SLO fusion proteins were degraded if secreted into the E. coli periplasm, but intact, soluble MBP-SLO fusion proteins were produced at high levels in the cytoplasm. Active S…
Oligomeric Sensor Kinase DcuS in the Membrane of Escherichia coli and in Proteoliposomes: Chemical Cross-linking and FRET Spectroscopy
2010
The DcuSR (dicarboxylate uptake sensor and regulator) system of Escherichia coli is a typical two-component system consisting of a membranous sensor kinase (DcuS) and a cytoplasmic response regulator (DcuR) (11, 26, 48). DcuS responds to C4-dicarboxylates like fumarate, malate, or succinate (19). In the presence of the C4-dicarboxlates, the expression of the genes of anaerobic fumarate respiration (dcuB, fumB, and frdABCD) and of aerobic C4-dicarboxylate uptake (dctA) is activated. DcuS is a histidine protein kinase composed of two transmembrane helices with an intermittent sensory PAS domain in the periplasm (PASP) that was also termed the PDC domain (for PhoQ/DcuS/DctB/CitA domain or fold…
Cephalosporin resistant Escherichia coli from cancer patients in Cairo, Egypt.
2013
Cephalosporin-resistant Escherichia coli has been increasingly reported worldwide. In this study, 32 cephalosporin resistant E. coli isolates identified from cancer patients in Cairo, Egypt in 2009-2010 were analyzed. Twenty-three were of phylogenetic group D, seven A and one each B1 and B2. By rep-PCR 15 phylogroup D isolates were grouped in four clusters, one with sequence type (ST) 405 and three ST68. Seventeen isolates showed single patterns. blaCTX-M-15 and aac(6')-Ib-cr were the most common resistance determinants. blaOXA-48 and blaVIM were also detected. Multidrug resistant E. coli seriously affects healthcare, especially in immunocompromised hosts, such as cancer patients.
VIRULENCE FACTORS AND ANTIMICROBIAL RESISTANCE OF ESCHERICHIA COLI ST131 IN COMMUNITY-ONSET HEALTHCARE-ASSOCIATED INFECTIONS IN SICILY, ITALY
2017
Escherichia coli ST131 is an emerging resistant agent recently called “superbug” in England. This strain is responsible of community-acquired urinary tract infections and nowadays showing increasing resistance to antibiotics like fluoroquinolones and cephalosporins. Survey of virulent bacterial clone is relevant to control its spreading in community. We aim to assess the circulation of resistant clones Escherichia coli ST131 outside of the hospital to prompt control of outbreak in our geographical area. We selected 105 E. coli resistant isolates from community-acquired urinary infections and performed a multiplex PCR to evaluate if they belonged to the ST131 type. We investigated their set …
Large-scale compression of genomic sequence databases with the Burrows-Wheeler transform
2012
Motivation The Burrows-Wheeler transform (BWT) is the foundation of many algorithms for compression and indexing of text data, but the cost of computing the BWT of very large string collections has prevented these techniques from being widely applied to the large sets of sequences often encountered as the outcome of DNA sequencing experiments. In previous work, we presented a novel algorithm that allows the BWT of human genome scale data to be computed on very moderate hardware, thus enabling us to investigate the BWT as a tool for the compression of such datasets. Results We first used simulated reads to explore the relationship between the level of compression and the error rate, the leng…
Assembly of human contact phase proteins and release of bradykinin at the surface of curli-expressing Escherichia coli.
1996
Previous work has demonstrated that most strains of the human pathogen Streptococcus pyogenes bind kininogens through M protein, a fibrous surface protein and virulence determinant. Here we find that strains of several other pathogenic bacterial species, both Gram-positive and Gram-negative, isolated from patients with sepsis, also bind kininogens, especially kininogen (HK). The most pronounced interaction was seen between HK and Escherichia coli. Among clinical isolates of E. coli, the majority of the enterohaemorrhagic, enterotoxigenic, and sepsis strains, but none of the enteroinvasive and enteropathogenic strains, bound HK. Binding of HK to E. coli correlated with the expression of curl…
High risk of bacterobilia in advanced experimental chronic fasciolosis
2006
Fasciolosis is recognized as an important human disease. Wistar rats experimentally infected with Fasciola hepatica were examined using data obtained in the advanced chronic state of the disease (200, 300 and 400 days post-infection, dpi). Pigment stones (PS) and bile specimens were collected. The same procedure was applied in control rats. Liver tests were determined using stored serum samples. Bacteriological bile culture revealed viable bacteria (Escherichia coli, 45% of cases, Enterococcus faecalis, 45% and Klebsiella pneumoniae, 10%). The presence of bacterobilia was associated with liver serum enzymes, including aspartate aminotransferase (AST or SGOT), alanine aminotransferase (ALT o…
[The risk of Escherichia coli O157:H7 in Sicily, through imported bovines for slaughter]
2001
The presence of Escherichia coli 0157:117, an emerging pathogen that has been. responsible of serious epidemics of hemorrhagic colitis and hemolytic-uremic syndrome in several countries, has been detected in rectal swabs in 13 out of 201 (6,5%) calves imported in Sicily (Italy) from France, 7 out of 154 (4,5%) calves imported from Spain, and only one out of 207 (0,5%) calves from Sicilian farms. The only positive Sicilian calf was from a farm where imported calves had been stalled some days before. All the isolates showed eaeA and hlyA virulence genes. Genes for verocytotoxins were detected in 18 isolates, which showed the following genotypes: stx2c (12 isolates), stxl stx2 (4 isolates), sa…