A multifactor regulatory circuit involving H-NS, VirF and an antisense RNA modulates transcription of the virulence gene icsA of Shigella flexneri.
type: Distribution
access URL: https://riip.hal.science/pasteur-00975905
format: HTML
issued: 2026-05-05T15:48:25.233547
modified: 2026-05-05T15:48:25.210613

test_moissonnage_selune
type: Agent

A multifactor regulatory circuit involving H-NS, VirF and an antisense RNA modulates transcription of the virulence gene icsA of Shigella flexneri.
type: Dataset
contact point: Organization
  fn: CCSD
keyword: mesh-transcription-genetic
keyword: mesh-virulence-factors
keyword: mesh-transcription-factors
keyword: journal-articles
keyword: sdvmplife-sciences-q-biomicrobiology-and-parasitology
keyword: mesh-bacterial-proteins
keyword: mesh-base-sequence
keyword: mesh-promoter-regions-genetic
keyword: mesh-molecular-sequence-data
keyword: mesh-binding-sites
keyword: mesh-dna-binding-proteins
keyword: mesh-rna-bacterial
keyword: mesh-trans-activators
keyword: mesh-rna-antisense
keyword: infoeu-reposemanticsarticle
keyword: mesh-gene-expression-regulation-bacterial
landing page: 0305-1048
description: The icsA gene of Shigella encodes a structural protein involved in colonization of the intestinal mucosa by bacteria. This gene is expressed upon invasion of the host and is controlled by a complex regulatory circuit involving the nucleoid protein H-NS, the AraC-like transcriptional activator VirF, and a 450 nt antisense RNA (RnaG) acting as transcriptional attenuator. We investigated on the interplay of these factors at the molecular level. DNase I footprints reveal that both H-NS and VirF bind to a region including the icsA and RnaG promoters. H-NS is shown to repress icsA transcription at 30°C but not at 37°C, suggesting a significant involvement of this protein in the temperature-regulated expression of icsA. We also demonstrate that VirF directly stimulates icsA transcription and is able to alleviate H-NS repression in vitro. According to these results, icsA expression is derepressed in hns- background and overexpressed when VirF is provided in trans. Moreover, we find that RnaG-mediated transcription attenuation depends on 80 nt at its 5'-end, a stretch carrying the antisense region. Bases engaged in the initial contact leading to sense-antisense pairing have been identified using synthetic RNA and DNA oligonucleotides designed to rebuild and mutagenize the two stem-loop motifs of the antisense region.
issued: 2026-05-05T15:48:25.224333
language: en
modified: 2026-05-05T15:48:25.224338