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.
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.
Hardt
K
K
Centre d'Ingénierie des Protéines, Université de Liège, Belgium.
Joris
B
B
Lepage
S
S
Brasseur
R
R
Lampen
J O
JO
Frère
J M
JM
Fink
A L
AL
Ghuysen
J M
JM
D000595:Amino Acid Sequence; D001407:Bacillus / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000032:analysis; D015153:Blotting, Western; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D017930:Genes, Reporter; D008954:Models, Biological; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016376:Oligonucleotides, Antisense / Q000235:genetics; D046915:Penicillin-Binding Proteins; D010406:Penicillins / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010957:Plasmids; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D015398:Signal Transduction; D014166:Transferases / Q000737:chemistry; D014170:Transformation, Genetic; D001618:beta-Lactamases / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D016376:Oligonucleotides, Antisense; D046915:Penicillin-Binding Proteins; D010406:Penicillins; D010455:Peptides; D014166:Transferases; D001618:beta-Lactamases