Spx is a global effector impacting stress tolerance and biofilm formation in Staphylococcus aureus

Sünje Johanna Pamp, Dorte Frees, Susanne Engelmann, Michael Hecker, Hanne Ingmer

Research output: Contribution to journalJournal articleResearchpeer-review


In Bacillus subtilis, Spx was recently characterized as a novel type of global regulator whose activity is regulated by the redox status of the cells. In the present study, we demonstrate that inactivation of Spx in the important pathogen Staphylococcus aureus renders the cells hypersensitive to a wide range of stress conditions including high and low temperature, high osmolarity, and hydrogen peroxide. Moreover, growth was restricted under nonstress conditions. Two-dimensional gel electrophoresis revealed that the proteome of the spx mutant differs substantially from the proteome of wild-type cells, supporting the finding that Spx is also a global regulator in S. aureus. More specifically, we demonstrated that Spx is required for transcription of trxB, encoding thioredoxin reductase, under all growth conditions examined. As trxB is essential in S. aureus, we speculate that the severely reduced trxB transcription could account for some of the growth defects of the spx mutant. Inactivation of spx also enhanced biofilm formation. S. aureus biofillm formation is associated with the production of the polysaccharide intercellular adhesin encoded by the ica operon. Interestingly, our data indicate that the augmented capacity of the spx mutant to form biofilms is due to Spx modulating the expression of icaR, encoding a repressor of the structural ica genes (icaABCD). In summary, we conclude that Spx fulfills an important role for growth, general stress protection, and biofilm formation in S. aureus.
Original languageEnglish
JournalJournal of Bacteriology
Issue number13
Pages (from-to)4861-4870
Number of pages10
Publication statusPublished - 2006
Externally publishedYes


  • Bacterial Proteins
  • Biofilms
  • Chromosomes, Bacterial
  • DNA-Directed RNA Polymerases
  • Gene Deletion
  • Genes, Bacterial
  • Hydrogen Peroxide
  • Osmolar Concentration
  • Staphylococcus aureus
  • Temperature
  • BBX060AN9V Hydrogen Peroxide
  • EC DNA-Directed RNA Polymerases
  • adhesin
  • hydrogen peroxide
  • protein Spx
  • regulator protein
  • thioredoxin reductase
  • unclassified drug
  • article
  • Bacillus subtilis
  • bacterial gene
  • bacterial growth
  • biofilm
  • gel electrophoresis
  • gene inactivation
  • genetic transcription
  • high temperature
  • icaR gene
  • low temperature
  • nonhuman
  • osmolarity
  • oxidation reduction reaction
  • priority journal
  • repressor gene
  • stress
  • trxB gene
  • stress tolerance
  • Eubacteria Bacteria Microorganisms (Bacteria, Eubacteria, Microorganisms) - Endospore-forming Gram-Positives [07810] Bacillus subtilis species
  • Gram-Positive Cocci Eubacteria Bacteria Microorganisms (Bacteria, Eubacteria, Microorganisms) - Micrococcaceae [07702] Staphylococcus aureus species
  • Staphylococcus aureus ica gene [Micrococcaceae]
  • hydrogen peroxide 7722-84-1
  • icaR expression
  • Spx
  • thioredoxin reductase 9074-14-0
  • 03502, Genetics - General
  • 10060, Biochemistry studies - General
  • 10802, Enzymes - General and comparative studies: coenzymes
  • 31000, Physiology and biochemistry of bacteria
  • 31500, Genetics of bacteria and viruses
  • Biochemistry and Molecular Biophysics
  • two-dimensional gel electrophoresis electrophoretic techniques, laboratory techniques
  • Enzymology
  • Molecular Genetics

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