title: O serotype-independent susceptibility of Pseudomonas aeruginosa to lectin-like pyocins.
abstract: Lectin-like bacteriocins of the LlpA family, originally identified in plant-associated bacteria, are narrow-spectrum antibacterial proteins composed of two tandemly organized monocot mannose-binding lectin (MMBL) domains. The LlpA-like bacteriocin of Pseudomonas aeruginosa C1433, pyocin L1, lacks any similarity to known P. aeruginosa bacteriocins. The initial interaction of pyocin L1 with target cells is mediated by binding to d-rhamnose, present in the common polysaccharide antigen of lipopolysaccharides (LPS), but the actual cytotoxic mechanism is unknown. In this study, we characterized the activity range of pyocin L1 and two additional L pyocins revealed by genome mining, representing two highly diverged LlpA groups in P. aeruginosa. The recombinant proteins exhibit species-specific antagonistic activities down to nanomolar concentrations against clinical and environmental P. aeruginosa strains, including several multidrug-resistant isolates. The overlap in target strain spectrum between two close homologues of the pyocin L1 group is only minimal, contrasting with the considerable spectral redundancy of LlpA proteins reported for other Pseudomonas species. No correlation was found between L pyocin susceptibility and phylogenetic relatedness of P. aeruginosa isolates. Sensitive strains were retrieved in 13 out of 15 O serotypes tested, excluding the possibility that the highly variable and immunogenic O serotype antigen of the LPS coating would represent a dominant susceptibility-discriminating factor.
authors.affiliation: Centre of Microbial and Plant Genetics, University of Leuven, 3001, Heverlee, Belgium.
authors.forename: Maarten G K
authors.initials: MG
authors.lastname: Ghequire
authors.forename: Jozef
authors.initials: J
authors.lastname: Dingemans
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Pirnay
authors.forename: Daniel
authors.initials: D
authors.lastname: De Vos
authors.forename: Pierre
authors.initials: P
authors.lastname: Cornelis
authors.forename: René
authors.initials: R
authors.lastname: De Mot
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011550:Pseudomonas aeruginosa / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D011709:Pyocins / Q000737:chemistry / Q000494:pharmacology*; D065288:Serogroup
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D011709:Pyocins
keywords: Bacteriocin; LlpA; MMBL lectin; O-specific antigen; lipopolysaccharide