title: Family of class I lantibiotics from actinomycetes and improvement of their antibacterial activities.
abstract: Lantibiotics, an abbreviation for "lanthionine-containing antibiotics", interfere with bacterial metabolism by a mechanism not exploited by the antibiotics currently in clinical use. Thus, they have aroused interest as a source for new therapeutic agents because they can overcome existing resistance mechanisms. Starting from fermentation broth extracts preselected from a high-throughput screening program for discovering cell-wall inhibitors, we isolated a series of related class I lantibiotics produced by different genera of actinomycetes. Analytical techniques together with explorative chemistry have been used to establish their structures: the newly described compounds share a common 24 aa sequence with the previously reported lantibiotic planosporicin (aka 97518), differing at positions 4, 6, and 14. All of these compounds maintain an overall -1 charge at physiological pH. While all of these lantibiotics display modest antibacterial activity, their potency can be substantially modulated by progressively eliminating the negative charges, with the most active compounds carrying basic amide derivatives of the two carboxylates originally present in the natural compounds. Interestingly, both natural and chemically modified lantibiotics target the key biosynthetic intermediate lipid II, but the former compounds do not bind as effectively as the latter in vivo. Remarkably, the basic derivatives display an antibacterial potency and a killing effect similar to those of NAI-107, a distantly related actinomycete-produced class I lantibiotic which lacks altogether carboxyl groups and which is a promising clinical candidate for treating Gram-positive infections caused by multi-drug-resistant pathogens.
authors.affiliation: †Naicons srl, 20139 Milano, Italy.|‡KtedoGen srl, 21046 Milano, Italy.
authors.forename: Sonia I
authors.initials: SI
authors.lastname: Maffioli
authors.affiliation: †Naicons srl, 20139 Milano, Italy.|‡KtedoGen srl, 21046 Milano, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Monciardini
authors.affiliation: †Naicons srl, 20139 Milano, Italy.|§ITB-CNR Segrate, 20090 Milano, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Catacchio
authors.affiliation: †Naicons srl, 20139 Milano, Italy.|§ITB-CNR Segrate, 20090 Milano, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Mazzetti
authors.affiliation: ⊥Institute of Medical Microbiology, Immunology and Parasitology, Pharmaceutical Microbiology Section, University of Bonn, 53113 Bonn, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Münch
authors.affiliation: ∥Need Pharma, 20122 Milano, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Brunati
authors.affiliation: ⊥Institute of Medical Microbiology, Immunology and Parasitology, Pharmaceutical Microbiology Section, University of Bonn, 53113 Bonn, Germany.
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Sahl
authors.affiliation: †Naicons srl, 20139 Milano, Italy.|‡KtedoGen srl, 21046 Milano, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Donadio
mesh_terms: D039903:Actinobacteria / Q000737:chemistry / Q000145:classification / Q000254:growth & development / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D001430:Bacteriocins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D004353:Drug Evaluation, Preclinical / Q000379:methods; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D013302:Streptomyces / Q000145:classification / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins