title: A unique lantibiotic, thermophilin 1277, containing a disulfide bridge and two thioether bridges.
abstract: OBJECTIVE
  To identify the chemical structure of a bacteriocin, thermophilin 1277, produced by Streptococcus thermophilus SBT1277.
  
  
  RESULTS
  Thermophilin 1277 was purified and partial N-terminal sequence analysis revealed 6 unidentified amino acids amongst 31 amino acids residues. A 2.7-kbp region containing the thermophilin 1277 structural gene (tepA) encoding 58 amino acids was cloned and sequenced. Mature thermophilin 1277 (33 amino acids) was preceded by a 25-amino acid putative leader peptide containing a double glycine cleavage motif. Peptide sequence analysis following chemical modification of thermophilin 1277 revealed that the Cys21 and Cys29 residues form a disulfide bridge and that Thr8 or Thr10 forms two 3-methyllanthionines with Cys13 or Cys32 via thioether bridges. Antimicrobial activity was disrupted by ethanethiol or reductive agent treatments, indicating that the internal amino acid modifications are crucial for the activity.
  
  
  CONCLUSIONS
  Thermophilin 1277 from Strep. thermophilus SBT1277 belongs to the class of AII-type lantibiotics that has a disulfide and two thioether bridges.
  
  
  CONCLUSIONS
  This is the first report of a lantibiotic produced by a GRAS species of Strep. thermophilus; thermophilin 1277 has a unique structure containing both a disulfide bridge and two thioether bridges that are crucial for its activity.
authors.affiliation: Technology and Research Institute, Snow Brand Milk Products, Co. Ltd, Minamidai 1-1-2, Kawagoe, Japan. kabuki@snowbrand.co.jp
authors.forename: T
authors.initials: T
authors.lastname: Kabuki
authors.forename: H
authors.initials: H
authors.lastname: Uenishi
authors.forename: Y
authors.initials: Y
authors.lastname: Seto
authors.forename: T
authors.initials: T
authors.lastname: Yoshioka
authors.forename: H
authors.initials: H
authors.lastname: Nakajima
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry*; D001430:Bacteriocins / Q000737:chemistry* / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D013058:Mass Spectrometry; D009876:Operon / Q000235:genetics; D017422:Sequence Analysis, DNA; D048249:Streptococcus thermophilus / Q000235:genetics* / Q000378:metabolism; D013440:Sulfides
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D013440:Sulfides