title: Population genetic structure of Legionella pneumophila inferred from RNA polymerase gene (rpoB) and DotA gene (dotA) sequences.
abstract: The population structure of Legionella pneumophila was studied by using partial RNA polymerase gene (rpoB) and DotA gene (dotA) sequences. Trees inferred from rpoB sequences showed that two subspecies of L. pneumophila, Legionella pneumophila subsp. pneumophila and Legionella pneumophila subsp. fraseri, were clearly separated genetically. In both rpoB and dotA trees, 79 Korean isolates used in this study constituted six clonal populations, four of which (designated subgroups P-I to P-IV) were identified in L. pneumophila subsp. pneumophila and two of which (designated subgroups F-I and F-II) were identified in L. pneumophila subsp. fraseri. Although the relationships among subgroups were not identical, such subgrouping was congruent between the rpoB and dotA trees. Type strains of several serogroups did not belong to any subgroup, presumably because isolates similar to these strains were not present among our local sample of the population. There was evidence that horizontal gene transfer or recombination had occurred within L. pneumophila. Contrary to the phylogeny from rpoB and the taxonomic context, subgroups P-III and P-IV of L. pneumophila subsp. pneumophila proved to be closely related to those of L. pneumophila subsp. fraseri or showed a distinct clustering in the dotA tree. It can be inferred that dotA of subgroups P-III and P-IV has been transferred horizontally from other subspecies. The diverse distribution of serogroup 1 strains through the gene trees suggests that surface antigen-coding genes that determine serogroup can be exchanged. Thus, it can be inferred that genetic recombination has been important in the evolution of L. pneumophila.
authors.affiliation: Department of Microbiology and Cancer Research Institute, Institute of Endemic Diseases, SNUMRC, Seoul National University College of Medicine, Seoul National University Hospital, Seoul 110-799, 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: Man-Suk
authors.initials: MS
authors.lastname: Park
authors.forename: Keun-Hwa
authors.initials: KH
authors.lastname: Lee
authors.forename: So-Yon
authors.initials: SY
authors.lastname: Woo
authors.forename: Yeo-Jun
authors.initials: YJ
authors.lastname: Yun
authors.forename: Yoon-Hoh
authors.initials: YH
authors.lastname: Kook
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D016952:Legionella pneumophila / Q000145:classification* / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D012703:Serotyping
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; C440002:DotA protein, Legionella pneumophila; D008565:Membrane Proteins; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit