Skip to main content
padlock icon - secure page this page is secure

Free Content An RpoS (σS) homologue regulates acylhomoserine lactone-dependent autoinduction in Ralstonia solanacearum

Download Article:
Many bacteria sense an appropriate growth condition or a critical population density for gene expression by producing acylhomoserine lactones (acyl-HSLs) that act as intercellular autoinduction signals. We recently showed that, in Ralstonia (Pseudomonas) solanacearum, a phytopathogenic bacterium, acyl-HSL production requires solI, which encodes a putative acyl-HSL synthase, and that its expression is positively regulated by the acyl-HSL-responsive SolR transcriptional regulator. This acyl-HSL-dependent autoinduction system is noteworthy because (i) it is regulated by a ‘higher level’ autoinducer system (responsive to 3-hydroxypalmitic acid methyl ester) via PhcA, a LysR-type transcriptional regulator and (ii) acyl-HSL production requires two additional unlinked loci. As reported here, cloning and sequencing of one of these other loci revealed that it encodes a homologue of RpoS, an alternative sigma factor (σS) that in other bacteria activates gene expression during stationary phase or in response to stress conditions. R. solanacearum RpoS (RpoSRso) was demonstrated to function as a σ factor because when introduced in trans into an Escherichia coli rpoS mutant it largely restored expression of the RpoS-dependent bolAp1 gene. Mutation of rpoSRso in R. solanacearum reduced survival during starvation and low pH conditions, but did not affect survival during exposure to hydrogen peroxide, high osmolarity or high temperature. This mutant was also altered in its production of several virulence factors and wilted tomato plants several days more slowly than the wild-type parent. Transcription of solR and solI were decreased in an rpoSRso background (thereby reducing acyl-HSL production), but neither mutations in solR, solI or phcA nor addition of acyl-HSLs affected rpoSRso expression. Therefore, in R. solanacearum the acyl-HSL-dependent autoinduction system is controlled both by a second autoinduction system and by the RpoSRso sigma factor.
No References
No Citations
No Supplementary Data
No Article Media
No Metrics

Document Type: Original Article

Affiliations: Plant Pathology and,

Publication date: April 1, 1998

  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more