Dataset Information

IS1414, an Escherichia coli insertion sequence with a heat-stable enterotoxin gene embedded in a transposase-like gene.

ABSTRACT: Enteroaggregative Escherichia coli (EAEC) heat-stable enterotoxin 1 (EAST1) was originally discovered in EAEC but has also been associated with enterotoxigenic E. coli (ETEC). Multiple genomic restriction fragments from each of three ETEC strains of human origin showed homology with an EAST1 gene probe. A single hybridizing fragment was detected on the plasmid of ETEC strain 27D that also encodes heat-stable enterotoxin Ib and colonization factor antigen I. We isolated and characterized this fragment, showing that it (i) carries an allele of astA nearly identical to that originally reported from EAEC 17-2 and (ii) expressed enterotoxic activity. Sequence analysis of the toxin coding region revealed that astA is completely embedded within a 1,209-bp open reading frame (ORF1), whose coding sequence is on the same strand but in the -1 reading frame in reference to the toxin gene. In vitro expression of the predicted M(r)- approximately 46,000 protein product of ORF1 was demonstrated. ORF1 is highly similar to transposase genes of IS285 from Yersinia pestis, IS1356 from Burkholderia cepacia, and ISRm3 from Rhizobium meliloti. It is bounded by 30-bp imperfect inverted repeat sequences and flanked by 8-bp direct repeats. Based on these structural features, pathognomonic of a regular insertion sequence, this element was designated IS1414. Preliminary experiments to show IS1414 translocation were unsuccessful. Overlapping genes of the type suggested by the IS1414 core region have heretofore not been described in bacteria. It seems to offer a most efficient mechanism for intragenomic and horizontal dissemination of EAST1.

SUBMITTER: McVeigh A

PROVIDER: S-EPMC101527 | biostudies-literature | 2000 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

IS1414, an Escherichia coli insertion sequence with a heat-stable enterotoxin gene embedded in a transposase-like gene.

McVeigh A A Fasano A A Scott D A DA Jelacic S S Moseley S L SL Robertson D C DC Savarino S J SJ

Infection and immunity 20001001 10

Enteroaggregative Escherichia coli (EAEC) heat-stable enterotoxin 1 (EAST1) was originally discovered in EAEC but has also been associated with enterotoxigenic E. coli (ETEC). Multiple genomic restriction fragments from each of three ETEC strains of human origin showed homology with an EAST1 gene probe. A single hybridizing fragment was detected on the plasmid of ETEC strain 27D that also encodes heat-stable enterotoxin Ib and colonization factor antigen I. We isolated and characterized this fra ...[more]

PMID: 10992475

Similar Datasets

Project description:Enterotoxigenic E. coli (ETEC) are endemic in low-resource settings and cause robust secretory diarrheal disease in children less than five years of age. ETEC cause secretory diarrhea by producing the heat-stable (ST) and/or heat-labile (LT) enterotoxins. Recent studies have shown that ETEC can be carried asymptomatically in children and adults, but how ETEC subvert mucosal immunity to establish intestinal residency remains unclear. Macrophages are innate immune cells that can be exploited by enteric pathogens to evade mucosal immunity, so we interrogated the ability of ETEC and other E. coli pathovars to survive within macrophages. Using gentamicin protection assays, we show that ETEC H10407 is phagocytosed more readily than other ETEC and non-ETEC isolates. Furthermore, we demonstrate that ETEC H10407, at high bacterial burdens, causes nitrite accumulation in macrophages, which is indicative of a proinflammatory macrophage nitric oxide killing response. However, at low bacterial burdens, ETEC H10407 remains viable within macrophages for an extended period without nitrite accumulation. We demonstrate that LT, but not ST, intoxication decreases the number of ETEC phagocytosed by macrophages. Furthermore, we now show that macrophages exposed simultaneously to LPS and LT produce IL-33, which is a cytokine implicated in promoting macrophage alternative activation, iron recycling, and intestinal repair. Lastly, iron restriction using deferoxamine induces IL-33 receptor (IL-33R) expression and allows ETEC to escape macrophages. Altogether, these data demonstrate that LT provides ETEC with the ability to decrease the perceived ETEC burden and suppresses the initiation of inflammation. Furthermore, these data suggest that host IL-33/IL-33R signaling may augment pathways that promote iron restriction to facilitate ETEC escape from macrophages. These data could help explain novel mechanisms of immune subversion that may contribute to asymptomatic ETEC carriage.

Dataset Information

IS1414, an Escherichia coli insertion sequence with a heat-stable enterotoxin gene embedded in a transposase-like gene.

Publications

IS1414, an Escherichia coli insertion sequence with a heat-stable enterotoxin gene embedded in a transposase-like gene.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets