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PLoS Pathog. 2006 Aug;2(8):e81.

H-NS mediates the silencing of laterally acquired genes in bacteria.

Author information

1
Molecular Microbiology Group, Institute of Food Research, Colney, Norwich, United Kingdom.

Erratum in

  • PLoS Pathog. 2007 Mar;3(3):e38.

Abstract

Histone-like nucleoid structuring protein (H-NS) is a modular protein that is associated with the bacterial nucleoid. We used chromatin immunoprecipitation to determine the binding sites of H-NS and RNA polymerase on the Salmonella enterica serovar Typhimurium chromosome. We found that H-NS does not bind to actively transcribed genes and does not co-localize with RNA polymerase. This shows that H-NS principally silences gene expression by restricting the access of RNA polymerase to the DNA. H-NS had previously been shown to preferentially bind to curved DNA in vitro. In fact, at the genomic level we discovered that the level of H-NS binding correlates better with the AT-content of DNA. This is likely to have evolutionary consequences because we show that H-NS binds to many Salmonella genes acquired by lateral gene transfer, and functions as a gene silencer. The removal of H-NS from the cell causes un-controlled expression of several Salmonella pathogenicity islands, and we demonstrate that this has deleterious consequences for bacterial fitness. Our discovery of this novel role for H-NS may have implications for the acquisition of foreign genes by enteric bacteria.

PMID:
16933988
PMCID:
PMC1550270
DOI:
10.1371/journal.ppat.0020081
[Indexed for MEDLINE]
Free PMC Article

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