title: Purification and Characterization of Suicin 65, a Novel Class I Type B Lantibiotic Produced by Streptococcus suis.
abstract: Bacteriocins are antimicrobial peptides of bacterial origin that are considered as a promising alternative to the use of conventional antibiotics. Recently, our laboratory reported the purification and characterization of two lantibiotics, suicin 90-1330 and suicin 3908, produced by the swine pathogen and zoonotic agent Streptococcus suis (serotype 2). In this study, a novel bacteriocin produced by S. suis has been identified and characterized. The producing strain S. suis 65 (serotype 2) was found to belong to the sequence type 28, that includes strains known to be weakly or avirulent in a mouse model. The bacteriocin, whose production was only possible following growth on solid culture medium, was purified to homogeneity by cationic exchange and reversed-phase high-pressure liquid chromatography. The bacteriocin, named suicin 65, was heat, pH and protease resistant. Suicin 65 was active against all S. suis isolates tested, including antibiotic resistant strains. Amino acid sequencing of the purified bacteriocin by Edman degradation revealed the presence of modified amino acids suggesting a lantibiotic. Using the partial sequence obtained, a blast was performed against published genomes of S. suis and allowed to identify a putative lantibiotic locus in the genome of S. suis 89-1591. From this genome, primers were designed and the gene cluster involved in the production of suicin 65 by S. suis 65 was amplified by PCR. Sequence analysis revealed the presence of ten open reading frames, including a duplicate of the structural gene. The structural genes (sssA and sssA') of suicin 65 encodes a 25-amino acid residue leader peptide and a 26-amino acid residue mature peptide yielding an active bacteriocin with a deducted molecular mass of 3,005 Da. Mature suicin 65 showed a high degree of identity with class I type B lantibiotics (globular structure) produced by Streptococcus pyogenes (streptococcin FF22; 84.6%), Streptococcus macedonicus (macedocin ACA-DC 198; 84.6%), and Lactococcus lactis subsp. lactis (lacticin 481; 74.1%). Further studies will evaluate the ability of suicin 65 or the producing strain to prevent experimental S. suis infections in pigs.
authors.affiliation: Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Katy
authors.initials: K
authors.lastname: Vaillancourt
authors.affiliation: Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada.
authors.forename: Geneviève
authors.initials: G
authors.lastname: LeBel
authors.affiliation: Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada.|Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Fonds de Recherche du Québec - Nature et Technologies (FQRNT), Saint-Hyacinthe, Quebec, Canada.
authors.forename: Michel
authors.initials: M
authors.lastname: Frenette
authors.affiliation: Public Health Ontario and Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Nahuel
authors.initials: N
authors.lastname: Fittipaldi
authors.affiliation: Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Fonds de Recherche du Québec - Nature et Technologies (FQRNT), Saint-Hyacinthe, Quebec, Canada.|Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Gottschalk
authors.affiliation: Groupe de Recherche en Écologie Buccale (GREB), Faculté de Médecine Dentaire, Université Laval, Quebec City, Quebec, Canada.|Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Fonds de Recherche du Québec - Nature et Technologies (FQRNT), Saint-Hyacinthe, Quebec, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Grenier
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001430:Bacteriocins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D017386:Sequence Homology, Amino Acid; D065288:Serogroup; D017011:Streptococcus suis / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D013552:Swine
chemical_list: D001430:Bacteriocins; D004269:DNA, Bacterial