Abstract |
The cytopathic effect (CPE) of Escherichia coli producing cytotoxic necrotizing factor type 1 (CNF1) was investigated by using a human epithelial cell (HeLa) model of infection with CNF1-producing E. coli BM2-1. This strain was shown to bind loosely, but massively, to HeLa cells. A 4-h interaction between bacteria and eukaryotic cells triggered the delayed appearance of a progressive dose-dependent CPE characterized by (i) intense swelling of cells accompanied by the formation of a dense network of actin stress fibers, (ii) inhibition of cell division due to a complete block in the G2 phase of the cell cycle, and (iii) nucleus swelling and chromatin fragmentation. These alterations resulted in cell death starting about 5 days after interaction. The absence of multinucleation clearly distinguished the CPE from the effect produced by cell-free culture supernatants of infected cells nor prevented by a CNF1-neutralizing antiserum. Pathogenicity was completely abolished after Tn5::phoA insertion mutagenesis in the cnf-1 structural gene but not restored by trans complementation with a recombinant plasmid containing intact cnf-1 and its promoter. These results suggest that a gene downstream of cnf-1, essential to the induction of the CPE, was affected by the mutation. On the other hand, transformation of the wild-type strain BM2-1 with the same recombinant plasmid leads to a significant increase in both CNF1 activity and CPE, demonstrating the direct contribution of CNF1 to the CPE. In conclusion, the pathogenicity of E. coli BM2-1 for HeLa cells results from a complex interaction involving cnf-1 and associated genes and possibly requiring a preliminary step of binding of bacterial organisms to target cells.
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Authors | J De Rycke, P Mazars, J P Nougayrede, C Tasca, M Boury, F Herault, A Valette, E Oswald |
Journal | Infection and immunity
(Infect Immun)
Vol. 64
Issue 5
Pg. 1694-705
(May 1996)
ISSN: 0019-9567 [Print] United States |
PMID | 8613380
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Bacterial Toxins
- Chromatin
- Cytotoxins
- DNA Primers
- DNA, Bacterial
- Escherichia coli Proteins
- Hemolysin Proteins
- cytotoxic necrotizing factor type 1
- DNA
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Topics |
- Bacterial Toxins
(biosynthesis, genetics, toxicity)
- Base Sequence
- Cell Death
(drug effects)
- Chromatin
(drug effects)
- Cytotoxins
(biosynthesis, genetics, toxicity)
- DNA
(metabolism)
- DNA Damage
- DNA Primers
(genetics)
- DNA, Bacterial
(genetics)
- Escherichia coli
(genetics, pathogenicity, physiology)
- Escherichia coli Proteins
- Fimbriae, Bacterial
(physiology)
- Genes, Bacterial
- HeLa Cells
- Hemolysin Proteins
(toxicity)
- Humans
- Mitosis
(drug effects)
- Molecular Sequence Data
- Virulence
(genetics)
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