The penicillin sensory transducer, BlaR, involved in the inducibility of beta-lactamase synthesis in Bacillus licheniformis is embedded in the plasma membrane via a four-alpha-helix bundle

Mol Microbiol. 1997 Mar;23(5):935-44. doi: 10.1046/j.1365-2958.1997.2761642.x.


Prediction studies, conformational analyses and membrane-topology mapping lead to the conclusion that the penicillin sensory transducer, BlaR, involved in the inducibility of beta-lactamase synthesis in Bacillus licheniformis, is embedded in the plasma membrane bilayer via four transmembrane segments TM1-TM4 that form a four-alpha-helix bundle. The extracellular 262-amino-acid-residue polypeptide, S340-R601, that is fused at the carboxy end of TM4, possesses the amino acid sequence signature of a penicilloyl serine transferase. It probably functions as penicillin sensor. As an independent entity, this polypeptide behaves as a high-affinity penicillin-binding protein. As a component of the full-size BlaR, it adopts a different conformation presumably because of interactions with the extracellular 63-amino-acid-residue P53-S115 loop that connects TM2 and TM3. Reception of the penicillin-induced signal requires a precise conformation of the sensor but it does not involve penicilloylation of the serine residue S402 of motif STYK. Signal transmission through the plasma membrane by the four-alpha-helix bundle may proceed in a way comparable to that of the aspartate receptor, Tar. Signal emission in the cytosol by the intracellular 189-amino-acid-residue Y134-K322 loop that connects TM3 and TM4, may proceed via the activation of a putative metallopeptidase.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Bacillus / chemistry*
  • Bacillus / genetics*
  • Bacillus / metabolism
  • Bacterial Proteins / analysis
  • Blotting, Western
  • Carrier Proteins / chemistry*
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • Cell Membrane / chemistry*
  • Cell Membrane / metabolism
  • Escherichia coli / genetics
  • Genes, Reporter
  • Models, Biological
  • Molecular Sequence Data
  • Molecular Structure
  • Oligonucleotides, Antisense / genetics
  • Penicillin-Binding Proteins*
  • Penicillins / metabolism
  • Peptides / chemistry
  • Plasmids
  • Protein Binding
  • Protein Conformation*
  • Protein Structure, Secondary
  • Signal Transduction
  • Transferases / chemistry
  • Transformation, Genetic
  • beta-Lactamases / metabolism


  • Bacterial Proteins
  • Carrier Proteins
  • Oligonucleotides, Antisense
  • Penicillin-Binding Proteins
  • Penicillins
  • Peptides
  • Transferases
  • beta-Lactamases