Paired-end sequence mapping detects extensive genomic rearrangement and translocation during divergence of Francisella tularensis subsp. tularensis and Francisella tularensis subsp. holarctica populations

Michael P. Dempsey, Joseph Nietfeldt, Jacques Ravel, Steven Hinrichs, Robert Crawford, Andrew K. Benson

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

Comparative genome hybridization of the Francisella tularensis subsp. tularensis and F. tularensis subsp. holarctica populations have shown that genome content is highly conserved, with relatively few genes in the F. tularensis subsp. tularensis genome being absent in other F. tularensis subspecies. To determine if organization of the genome differs between global populations of F. tularensis subsp. tularensis and F. tularensis subsp. holarctica, we have used paired-end sequence mapping (PESM) to identify regions of the genome where synteny is broken. The PESM approach compares the physical distances between paired-end sequencing reads of a library of a wild-type reference F. tularensis subsp. holarctica strain to the predicted lengths between the reads based on map coordinates of two different F. tularensis genome sequences. A total of 17 different continuous regions were identified in the F. tularensis subsp. holarctica genome (CRholarctica) which are noncontiguous in the F. tularensis subsp. tularensis genome. Six of the 17 different CRhularctica are positioned as adjacent pairs in the F. tularensis subsp. tularensis genome sequence but are translocated in F. tularensis subsp. holarctica, implying that their arrangements are ancestral in F. tularensis subsp. tularensis and derived in F. tularensis subsp. holarctica. PCR analysis of the CRhularctica in 88 additional F. tularensis subsp. tularensis and F. tularensis subsp. holarctica isolates showed that the arrangements of the CRholarctica are highly conserved, particularly in F. tularensis subsp. holarctica, consistent with the hypothesis that global populations of F. tularensis subsp. holarctica have recently experienced a periodic selection event or they have emerged from a recent clonal expansion. Two unique F. tularensis subsp. tularensis-like strains were also observed which likely are derived from evolutionary intermediates and may represent a new taxonomic unit.

Original languageEnglish (US)
Pages (from-to)5904-5914
Number of pages11
JournalJournal of bacteriology
Volume188
Issue number16
DOIs
StatePublished - Aug 1 2006

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ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology

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