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Coli K1 (coli + k1)

Distribution by Scientific Domains

Life Sciences	50%
Chemistry	50%

Selected Abstracts

The Hek outer membrane protein of Escherichia coli is an auto-aggregating adhesin and invasin

FEMS MICROBIOLOGY LETTERS, Issue 2 2007
Robert P. Fagan
Abstract Escherichia coli is the principal gram-negative causative agent of sepsis and meningitis in neonates. The pathogenesis of meningitis due to E. coli K1 involves mucosal colonization, transcytosis of epithelial cells, survival in the blood stream and eventually invasion of the meninges. The latter two aspects have been well characterized at a molecular level in the last decade. Less is known about the early stages of pathogenesis, i.e. adhesion to and invasion of gastrointestinal cells. Here, the characterization of the Hek protein is reported, which is expressed by neonatal meningitic E. coli (NMEC) and is localized to the outer membrane. It is demonstrated that this protein can cause agglutination of red blood cells and can mediate autoaggregation. Escherichia coli expressing this protein can adhere to and invade epithelial cells. So far, this is the first outer membrane protein in NMEC to be directly implicated in epithelial cell invasion. [source]

Genetic analysis of Escherichia coli K1 gastrointestinal colonization

MOLECULAR MICROBIOLOGY, Issue 6 2000
J. Martindale
Strains of Escherichia coli expressing the K1 polysaccharide capsule colonize the large intestine of newborn infants, and are the leading cause of Gram-negative septicaemia and meningitis in the neonatal period. We used signature-tagged mutagenesis (STM) to identify genes that E. coli K1 requires to colonize the gastrointestinal (GI) tract. A total of 2140 mTn5 mutants was screened for their capacity to colonize the GI tract of infant rats, and 16 colonization defective mutants were identified. The mutants have transposon insertions in genes affecting the synthesis of cell surface structures, membrane transporters, transcriptional regulators, enzymes in metabolic pathways, and in genes of unknown function, designated dgc (defective in GI colonization). Three dgcs are absent from the whole genome sequence of E. coli K-12, although related sequences are found in other pathogenic strains of E. coli and in Shigella flexneri. Additionally, immunohistochemistry was used to define the nature of the colonization defect in five mutants including all dgc mutants. STM was successfully applied to examine the factors involved in E. coli K1 colonization, and the findings are relevant to the pathogenesis of other enteric infections. [source]

Overexpression, crystallization and preliminary X-ray crystallographic analysis of Nudix hydrolase Orf141 from Escherichia coli K-1

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 9 2007
Junho Jung
Nudix hydrolases are a family of proteins that contain the characteristic amino-acid sequence GX5EX7REUXEEXGU (where U is usually I, L or V), the Nudix signature sequence. They catalyze the hydrolysis of a variety of nucleoside diphosphate derivatives such as nucleoside triphosphates, nucleotide sugars, ADP-ribose, dinucleotide coenzymes, diadenosine oligophosphates and capped RNAs. Recently, three new Nudix hydrolases have been found from Escherichia coli; one of them is Orf141, which cleaves pyrimidine deoxynucleoside triphosphates. Orf141 was cloned directly from E.,coli K1 strain and was overexpressed in E.,coli without any extra residues. Orf141 crystals were successfully obtained using polyethylene glycol 1500 as a precipitant at 285,K. X-ray diffraction data were collected to 3.1,Å resolution using synchrotron radiation. The crystal is a member of the rhombohedral space group H32, with unit-cell parameters a = b = 182.2, c = 62.3,Å, , = 90, , = 90, , = 120° (hexagonal setting). Two or three monomers are likely to be present in the asymmetric unit, with corresponding VM values of 2.92 and 1.95,Å3,Da,1 and solvent contents of 57.9 and 36.9%, respectively. [source]

Endosialidase NF Appears To Bind PolySia DP5 in a Helical Conformation

CHEMBIOCHEM, Issue 12 2006
Thomas Haselhorst Dr.
Phages infecting the polySia-encapsulated human pathogenE. coli K1 are equipped with capsule-degrading tail spikes known as endosialidases, which are the only identified enzymes that specifically degrade polySia. The X-ray crystallographic structure of endosialidase has been reported but it remains unclear how polySia interacts with the active site. Here we report STD and trNOE NMR experiments that investigate the binding mode of polySia DP5 at a molecular level. [source]