The PmrA/PmrB and RcsC/YojN/RcsB Systems Control Expression of the Salmonella O-antigen Chain Length Determinant

Mol Microbiol. 2006 Apr;60(1):39-50. doi: 10.1111/j.1365-2958.2006.05069.x.


The lipopolysaccharide (LPS) is the outermost component of the cell envelope in Gram-negative bacteria. It consists of the hydrophobic lipid A, a short non-repeating core oligosaccharide and a distal polysaccharide termed O-antigen. We report here that the PmrA/PmrB and RcsC/YojN/RcsB two-component systems of Salmonella enterica serovar Typhimurium independently promote transcription of the wzzst gene, which encodes a protein that determines the chain length of the O-antigen. We show that the regulatory proteins PmrA and RcsB footprint partially overlapping regions of the wzzst promoter stimulating transcription from the same start site. Induction of the PmrA/PmrB or RcsC/YojN/RcsB systems increased the fraction of LPS molecules containing 16-35 O-antigen subunits, leading to heightened resistance to serum. The LPS of a rcsB null mutant exhibited an altered mobility in the O-antigen subunits attached to the lipid A-core region when separated on a SDS/PAGE gel, suggesting that RcsB may regulate additional LPS genes. Inactivation of the wzzst gene eliminated the enhanced swarming behaviour exhibited by the rcsB mutant. That multiple regulatory systems control wzzst expression suggests that the Wzzst protein is required under different environmental conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Base Sequence
  • Gene Expression Regulation, Bacterial*
  • Molecular Sequence Data
  • Multienzyme Complexes / genetics
  • Multienzyme Complexes / metabolism
  • O Antigens / chemistry*
  • O Antigens / genetics
  • O Antigens / metabolism*
  • Phosphoprotein Phosphatases / genetics
  • Phosphoprotein Phosphatases / metabolism
  • Promoter Regions, Genetic
  • Protein Kinases / genetics
  • Protein Kinases / metabolism
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / growth & development
  • Salmonella typhimurium / metabolism
  • Salmonella typhimurium / physiology*
  • Signal Transduction*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcription, Genetic


  • Bacterial Proteins
  • Multienzyme Complexes
  • O Antigens
  • Transcription Factors
  • YojN protein, Salmonella typhimurium
  • pmrA protein, Bacteria
  • rol protein, Salmonella typhimurium
  • RcsB protein, Bacteria
  • Protein Kinases
  • Phosphoprotein Phosphatases