Commensal bacteria damage host DNA

Both pathogenic and good bacteria produce toxins that break eukaryotic DNA

Melissa Lee Phillips
Aug 9, 2006
Commensal strains of bacteria may establish themselves in the intestine by damaging eukaryotic cells, just like pathogenic bacteria, according to a new study in Science. The researchers found that both pathogenic and commensal strains of Escherichia coli possess a set of genes that lead to double-strand breaks in host cell DNA -- a mechanism that could also trigger intestinal cancer, the authors say. "It is a clear example of something that we think of as a virulence factor when we find it in pathogens that may be present in commensals as well," said David Schauer of MIT in Cambridge, Mass., who was not involved in the study. "That's really an exciting idea."Researchers led by Jean-Philippe Nougayrède of the National Institute for Agronomic Research in Toulouse, France, observed that some E. coli strains induce in eukaryotic cells a process called megalocytosis, in which the cell body and nucleus become enlarged...

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