Crystal structure of Bacillus cereus HlyIIR, a transcriptional regulator of the gene for pore-forming toxin hemolysin II

J Mol Biol. 2007 Jan 19;365(3):825-34. doi: 10.1016/j.jmb.2006.10.074. Epub 2006 Oct 26.


Production of Bacillus cereus and Bacillus anthracis toxins is controlled by a number of transcriptional regulators. Here we report the crystal structure of B. cereus HlyIIR, a regulator of the gene encoding the pore-forming toxin hemolysin II. We show that HlyIIR forms a tight dimer with a fold and overall architecture similar to the TetR family of repressors. A remarkable feature of the structure is a large internal cavity with a volume of 550 A(3) suggesting that the activity of HlyIIR is modulated by binding of a ligand, which triggers the toxin production. Virtual ligand library screening shows that this pocket can accommodate compounds with molecular masses of up to 400-500 Da. Based on structural data and previous biochemical evidence, we propose a model for HlyIIR interaction with the DNA.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacillus cereus / chemistry*
  • Bacterial Proteins / chemistry*
  • Bacterial Toxins / genetics*
  • Crystallography, X-Ray
  • DNA-Binding Proteins / chemistry
  • Dimerization
  • Hemolysin Proteins / genetics*
  • Ligands
  • Molecular Sequence Data
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Sequence Alignment
  • Static Electricity
  • Structural Homology, Protein
  • Transcription, Genetic*


  • Bacterial Proteins
  • Bacterial Toxins
  • DNA-Binding Proteins
  • Hemolysin Proteins
  • Ligands

Associated data

  • PDB/2FX0