title: Mosaic structure of pathogenicity islands in Legionella pneumophila.
abstract: A gene complex, dot/icm, located in two independent chromosomal loci of L. pneumophila, the causative agent of Legionnaires' disease, is related to virulence. To investigate the evolutionary pattern of these pathogenicity islands of L. pneumophila, portions of four genes in the dot/icm complex, namely, dotA, dotB, icmB, and icmT, were amplified, sequenced, and phylogenetically analyzed, in addition to rpoB, which encodes an RNA polymerase beta-subunit. The nucleotide sequences and phylogenetic analyses of these five genes of 96 L. pneumophila strains revealed that several subgroups of L. pneumophila proliferated clonally. However, incongruent gene tree topologies and the results of statistical testing (Templeton Willcoxon signed-ranked and incongruence length differences tests) indicated that the evolutionary histories of these genes within the pathogenicity islands are not uniform, and that they constitute a mosaic structure. In addition, the nonuniform grouping of some reference strains suggests that intraspecific recombination might be still occurring in nature or in the laboratory.
authors.affiliation: Department of Microbiology and Cancer Research Institute, Seoul National University Hospital, Seoul 110-799, Republic of Korea.
authors.forename: Kwan Soo
authors.initials: KS
authors.lastname: Ko
authors.forename: Hae Kyung
authors.initials: HK
authors.lastname: Lee
authors.forename: Mi-Yeoun
authors.initials: MY
authors.lastname: Park
authors.forename: Yoon-Hoh
authors.initials: YH
authors.lastname: Kook
mesh_terms: D000818:Animals; D001483:Base Sequence; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D019143:Evolution, Molecular; D005798:Genes, Bacterial; D044404:Genomic Islands / Q000235:genetics*; D016952:Legionella pneumophila / Q000235:genetics* / Q000472:pathogenicity; D015800:Protozoan Proteins / Q000235:genetics; D014774:Virulence
chemical_list: D015800:Protozoan Proteins; C075411:rpoB1 protein, Chlamydomonas reinhardtii; D012321:DNA-Directed RNA Polymerases