title: A novel lantibiotic acting on bacterial cell wall synthesis produced by the uncommon actinomycete Planomonospora sp.
abstract: Important classes of antibiotics acting on bacterial cell wall biosynthesis, such as beta-lactams and glycopeptides, are used extensively in therapy and are now faced with a challenge because of the progressive spread of resistant pathogens. A discovery program was devised to target novel peptidoglycan biosynthesis inhibitors capable of overcoming these resistance mechanisms. The microbial products were first screened according to their differential activity against Staphylococcus aureus and its L-form. Then, activities insensitive to the addition of a beta-lactamase cocktail or d-alanyl-d-alanine affinity resin were selected. Thirty-five lantibiotics were identified from a library of broth extracts produced by 40,000 uncommon actinomycetes. Five of them showed structural characteristics that did not match with any known microbial metabolite. In this study, we report on the production, structure determination, and biological activity of one of these novel lantibiotics, namely, planosporicin, which is produced by the uncommon actinomycete Planomonospora sp. Planosporicin is a 2194 Da polypeptide originating from 24 proteinogenic amino acids. It contains lanthionine and methyllanthionine amino acids generating five intramolecular thioether bridges. Planosporicin selectively blocks peptidoglycan biosynthesis and causes accumulation of UDP-linked peptidoglycan precursors in growing bacterial cells. On the basis of its mode of action and globular structure, planosporicin can be assigned to the mersacidin (20 amino acids, 1825 Da) and the actagardine (19 amino acids, 1890 Da) subgroup of type B lantibiotics. Considering its spectrum of activity against Gram-positive pathogens of medical importance, including multi-resistant clinical isolates, and its efficacy in vivo, planosporicin represents a potentially new antibiotic to treat emerging pathogens.
authors.affiliation: Vicuron Pharmaceuticals, Via R. Lepetit 34, 21040 Gerenzano, (VA) Italy.
authors.forename: Franca
authors.initials: F
authors.lastname: Castiglione
authors.forename: Linda
authors.initials: L
authors.lastname: Cavaletti
authors.forename: Daniele
authors.initials: D
authors.lastname: Losi
authors.forename: Ameriga
authors.initials: A
authors.lastname: Lazzarini
authors.forename: Lucia
authors.initials: L
authors.lastname: Carrano
authors.forename: Marina
authors.initials: M
authors.lastname: Feroggio
authors.forename: Ismaela
authors.initials: I
authors.lastname: Ciciliato
authors.forename: Emiliana
authors.initials: E
authors.lastname: Corti
authors.forename: Gianpaolo
authors.initials: G
authors.lastname: Candiani
authors.forename: Flavia
authors.initials: F
authors.lastname: Marinelli
authors.forename: Enrico
authors.initials: E
authors.lastname: Selva
mesh_terms: D000192:Actinomycetales / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000096:biosynthesis / Q000737:chemistry / Q000145:classification / Q000494:pharmacology; D001430:Bacteriocins / Q000096:biosynthesis / Q000737:chemistry* / Q000145:classification / Q000494:pharmacology; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D051379:Mice; D008813:Mice, Inbred ICR; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D010455:Peptides; C520832:planosporicin; C069959:mersacidin; C012993:gardimycin