IHF is required for the transcriptional regulation of the Desulfovibrio vulgaris Hildenborough orp operons

PLoS One. 2014 Jan 21;9(1):e86507. doi: 10.1371/journal.pone.0086507. eCollection 2014.


Transcriptional activation of σ(54)-dependent promoters is usually tightly regulated in response to environmental cues. The high abundance of potential σ(54)-dependent promoters in the anaerobe bacteria, Desulfovibrio vulgaris Hildenborough, reflects the high versatility of this bacteria suggesting that σ(54) factor is the nexus of a large regulatory network. Understanding the key players of σ(54)-regulation in this organism is therefore essential to gain insights into the adaptation to anaerobiosis. Recently, the D. vulgaris orp genes, specifically found in anaerobe bacteria, have been shown to be transcribed by the RNA polymerase coupled to the σ(54) alternative sigma factor. In this study, using in vitro binding experiments and in vivo reporter fusion assays in the Escherichia coli heterologous host, we showed that the expression of the divergent orp promoters is strongly dependent on the integration host factor IHF. Bioinformatic and mutational analysis coupled to reporter fusion activities and mobility shift assays identified two functional IHF binding site sequences located between the orp1 and orp2 promoters. We further determined that the D. vulgaris DVU0396 (IHFα) and DVU1864 (IHFβ) subunits are required to control the expression of the orp operons suggesting that they form a functionally active IHF heterodimer. Interestingly results obtained from the in vivo inactivation of DVU0396, which is required for orp operons transcription, suggest that several functionally IHF active homodimer or heterodimer are present in D. vulgaris.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics
  • Binding Sites / genetics
  • DNA-Binding Proteins / genetics
  • Desulfovibrio vulgaris / genetics*
  • Escherichia coli / genetics
  • Gene Expression Regulation, Bacterial / genetics
  • Genes, Bacterial / genetics
  • Integration Host Factors / genetics*
  • Molecular Sequence Data
  • Operon / genetics*
  • Promoter Regions, Genetic / genetics
  • Sequence Alignment
  • Transcription Factors / genetics
  • Transcription, Genetic / genetics*
  • Transcriptional Activation / genetics


  • Bacterial Proteins
  • DNA-Binding Proteins
  • Integration Host Factors
  • Transcription Factors

Grants and funding

The Agence nationale de la recherche ANR (ANR-12-ISV8-0003-01) funds this research project. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.