title: The structure of pyogenecin immunity protein, a novel bacteriocin-like immunity protein from Streptococcus pyogenes.
abstract: BACKGROUND
  Many Gram-positive lactic acid bacteria (LAB) produce anti-bacterial peptides and small proteins called bacteriocins, which enable them to compete against other bacteria in the environment. These peptides fall structurally into three different classes, I, II, III, with class IIa being pediocin-like single entities and class IIb being two-peptide bacteriocins. Self-protective cognate immunity proteins are usually co-transcribed with these toxins. Several examples of cognates for IIa have already been solved structurally. Streptococcus pyogenes, closely related to LAB, is one of the most common human pathogens, so knowledge of how it competes against other LAB species is likely to prove invaluable.
  
  
  RESULTS
  We have solved the crystal structure of the gene-product of locus Spy_2152 from S. pyogenes, (PDB:2fu2), and found it to comprise an anti-parallel four-helix bundle that is structurally similar to other bacteriocin immunity proteins. Sequence analyses indicate this protein to be a possible immunity protein protective against class IIa or IIb bacteriocins. However, given that S. pyogenes appears to lack any IIa pediocin-like proteins but does possess class IIb bacteriocins, we suggest this protein confers immunity to IIb-like peptides.
  
  
  CONCLUSIONS
  Combined structural, genomic and proteomic analyses have allowed the identification and in silico characterization of a new putative immunity protein from S. pyogenes, possibly the first structure of an immunity protein protective against potential class IIb two-peptide bacteriocins. We have named the two pairs of putative bacteriocins found in S. pyogenes pyogenecin 1, 2, 3 and 4.
authors.affiliation: Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439, USA. cchang@anl.gov
authors.forename: Changsoo
authors.initials: C
authors.lastname: Chang
authors.forename: Penny
authors.initials: P
authors.lastname: Coggill
authors.forename: Alex
authors.initials: A
authors.lastname: Bateman
authors.forename: Robert D
authors.initials: RD
authors.lastname: Finn
authors.forename: Marcin
authors.initials: M
authors.lastname: Cymborowski
authors.forename: Zbyszek
authors.initials: Z
authors.lastname: Otwinowski
authors.forename: Wladek
authors.initials: W
authors.lastname: Minor
authors.forename: Lour
authors.initials: L
authors.lastname: Volkart
authors.forename: Andrzej
authors.initials: A
authors.lastname: Joachimiak
mesh_terms: D000595:Amino Acid Sequence; D001430:Bacteriocins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D013297:Streptococcus pyogenes / Q000737:chemistry*
chemical_list: D001430:Bacteriocins