Mycoplasmas regulate the expression of heat-shock protein genes through CIRCE-HrcA interactions

Biochem Biophys Res Commun. 2008 Feb 29;367(1):213-8. doi: 10.1016/j.bbrc.2007.12.124. Epub 2007 Dec 28.


Mycoplasmas in general are rarely exposed to severe environmental changes except during its colonization and infection processes. Genomic analysis indicates that Mycoplasma hyopneumoniae possesses the genes of a single sigma factor and the HrcA repressor of negative regulation of the heat-shock response. A perfect inverted repeat sequence (5'-CTGGCACTT-N(9)-AAGTGCCAA-3') upstream of the DnaK gene has also been identified. In the present study, we demonstrate the functionality of HrcA-CIRCE interactions using the gel electrophoretic mobility shift assay. The presence of the unique sigma factor, HrcA repressor, and the CIRCE-like sequences reveals that mycoplasmal species may all use the negative regulatory mechanism in the heat-shock response. It is conceivable that mycoplasmas may have evolved a single HrcA repressor-based mechanism which might be the most simple and economical way of controlling HSP gene expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Base Sequence
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Electrophoretic Mobility Shift Assay
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Gene Expression Regulation, Bacterial*
  • Genes, Regulator*
  • Genomics
  • HSP70 Heat-Shock Proteins / genetics
  • HSP70 Heat-Shock Proteins / metabolism
  • Heat-Shock Proteins / genetics*
  • Heat-Shock Proteins / metabolism
  • Heat-Shock Response / genetics
  • Heat-Shock Response / physiology
  • Molecular Sequence Data
  • Mycoplasma hyopneumoniae / genetics*
  • Mycoplasma hyopneumoniae / physiology
  • Regulatory Sequences, Nucleic Acid / genetics*
  • Regulatory Sequences, Nucleic Acid / physiology
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Sigma Factor / genetics
  • Sigma Factor / metabolism


  • Bacterial Proteins
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • HSP70 Heat-Shock Proteins
  • Heat-Shock Proteins
  • Repressor Proteins
  • Sigma Factor
  • dnaK protein, E coli