Integration Host Factor is required for FarR repression of the farAB-encoded efflux pump of Neisseria gonorrhoeae

Eun Hee Lee, Stuart A. Hill, Ruth Napier, William M. Shafer

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


The farAB operon encodes an efflux pump system that mediates the resistance of Neisseria gonorrhoeae to antimicrobial long-chain fatty acids. We previously observed that expression of farAB is negatively regulated by the FarR repressor. In this study, we examined the molecular mechanism by which FarR represses expression of farAB. DNase I footprinting analysis, coupled with a deletion analysis of the farAB promoter region, indicated that FarR binds to three sites (termed sites A, B and C) within the DNA sequence upstream of farA; genetic analysis revealed, however, that site B is not required for FarR repression of farAB. This repression also required the presence of Integration Host Factor (IHF), which was found to bind to sequences located between FarR binding sites A and C. We determined that IHF binding to the farAB promoter region could inhibit transcription in vitro and that such binding induced a bending of the target DNA, which we propose to be important in regulating this operon. IHF binding to the promoter region was found to stabilize the binding of FarR to its binding sites A and C and as a consequence, enhanced repression of farAB expression mediated by FarR. We propose a model in which expression of the farAB-encoded efflux pump in N. gonorrhoeae is modulated by the DNA binding activities of FarR and IHF.

Original languageEnglish (US)
Pages (from-to)1381-1400
Number of pages20
JournalMolecular Microbiology
Issue number6
StatePublished - Jun 2006
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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