title: Lipopolysaccharide as shield and receptor for R-pyocin-mediated killing in Pseudomonas aeruginosa.
abstract: Pseudomonas aeruginosa produces three different types of bacteriocins: the soluble S-pyocins and the bacteriophage-like F- and R-pyocins. R-pyocins kill susceptible bacteria of the same or closely related species with high efficiency. Five different types of R-pyocins (R1- to R5-pyocins) have been described based on their killing spectra and tail fiber protein sequences. We analyzed the distribution of R-pyocin genes in a collection of clinical P. aeruginosa isolates. We found similar percentages of isolates not containing R-pyocins (28%) and isolates containing genes encoding R1-pyocins (25%), R2-pyocins (17%), and R5-pyocins (29%). The R-pyocin-deficient isolates were susceptible to R1-, R2-, and R5-pyocins, while most R2- and R5- pyocin producers were resistant. Determination of the O serotypes revealed that the R-pyocin-susceptible isolates belonged to serotypes O1, O3, and O6, while the R-pyocin-resistant isolates were serotype O10, O11, and O12 isolates. We hypothesized that O-serotype-specific lipopolysaccharide (LPS) packaging densities may account for the distinct accessibilities of R-pyocins to their receptors at the cell surface. Using genetically defined LPS mutants, we showed that the l-Rha residue and two distinct d-Glc residues of the outer core are part of the receptor sites for R1-, R2-, and R5-pyocins, respectively. To illustrate R-pyocin-mediated intraspecies biological warfare, we monitored the population dynamics of two different R-pyocin-producing P. aeruginosa clones of sequential respiratory isolates obtained from a colonized patient. The results of this study highlight the potential role of R-pyocins in shaping bacterial populations during host colonization and support use of these molecules as specific and potent bactericidal agents.
authors.affiliation: Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland.
authors.forename: Thilo
authors.initials: T
authors.lastname: Köhler
authors.forename: Viviane
authors.initials: V
authors.lastname: Donner
authors.forename: Christian
authors.initials: C
authors.lastname: van Delden
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000633:toxicity*; D000898:Antibiosis; D006801:Humans; D008070:Lipopolysaccharides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D009154:Mutation; D019081:O Antigens / Q000032:analysis; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D011709:Pyocins / Q000378:metabolism / Q000633:toxicity*; D012703:Serotyping
chemical_list: D000900:Anti-Bacterial Agents; D008070:Lipopolysaccharides; D019081:O Antigens; D011709:Pyocins