title: Conservation of genome content and virulence determinants among clinical and environmental isolates of Pseudomonas aeruginosa.
abstract: Pseudomonas aeruginosa is a ubiquitous environmental bacterium capable of causing a variety of life-threatening human infections. The genetic basis for preferential infection of certain immunocompromised patients or individuals with cystic fibrosis by P. aeruginosa is not understood. To establish whether variation in the genomic repertoire of P. aeruginosa strains can be associated with a particular type of infection, we used a whole-genome DNA microarray to determine the genome content of 18 strains isolated from the most common human infections and environmental sources. A remarkable conservation of genes including those encoding nearly all known virulence factors was observed. Phylogenetic analysis of strain-specific genes revealed no correlation between genome content and infection type. Clusters of strain-specific genes in the P. aeruginosa genome, termed variable segments, appear to be preferential sites for the integration of novel genetic material. A specialized cloning vector was developed for capture and analysis of these genomic segments. With this capture system a site associated with the strain-specific ExoU cytotoxin-encoding gene was interrogated and an 80-kb genomic island carrying exoU was identified. These studies demonstrate that P. aeruginosa strains possess a highly conserved genome that encodes genes important for survival in numerous environments and allows it to cause a variety of human infections. The acquisition of novel genetic material, such as the exoU genomic island, through horizontal gene transfer may enhance colonization and survival in different host environments.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Wolfgang
authors.forename: Bridget R
authors.initials: BR
authors.lastname: Kulasekara
authors.forename: Xiaoyou
authors.initials: X
authors.lastname: Liang
authors.forename: Dana
authors.initials: D
authors.lastname: Boyd
authors.forename: Kai
authors.initials: K
authors.lastname: Wu
authors.forename: Qing
authors.initials: Q
authors.lastname: Yang
authors.forename: C Garrett
authors.initials: CG
authors.lastname: Miyada
authors.forename: Stephen
authors.initials: S
authors.lastname: Lory
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D005618:Fresh Water; D020869:Gene Expression Profiling; D022761:Gene Transfer, Horizontal; D005822:Genetic Vectors / Q000235:genetics; D016680:Genome, Bacterial; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D011552:Pseudomonas Infections / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000472:pathogenicity; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014170:Transformation, Genetic; D014774:Virulence / Q000235:genetics*; D014861:Washington; D014871:Water Microbiology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; C111749:pseudomonas exoprotein A protein, Pseudomonas aeruginosa