title: Bacterial genome adaptation to niches: divergence of the potential virulence genes in three Burkholderia species of different survival strategies.
abstract: BACKGROUND
  Two closely related species Burkholderia mallei (Bm) and Burkholderia pseudomallei (Bp) are serious human health hazards and are potential bio-warfare agents, whereas another closely related species Burkholderia thailandensis (Bt) is a non-pathogenic saprophyte. To investigate the genomic factors resulting in such a dramatic difference, we first identified the Bm genes responsive to the mouse environment, and then examined the divergence of these genes in Bp and Bt.
  
  
  RESULTS
  The genes down-expressed, which largely encode cell growth-related proteins, are conserved well in all three species, whereas those up-expressed, which include potential virulence genes, are less well conserved or absent notably in Bt. However, a substantial number of up-expressed genes is still conserved in Bt. Bm and Bp further diverged from each other in a small number of genes resulting from unit number changes in simple sequence repeats (ssr) in the homologs.
  
  
  CONCLUSIONS
  Our data suggest that divergent evolution of a small set of genes, rather than acquisition or loss of pathogenic islands, is associated with the development of different life styles in these bacteria of similar genomic contents. Further divergence between Bm and Bp mediated by ssr changes may reflect different adaptive processes of Bm and Bp fine-tuning into their host environments.
authors.affiliation: The Institute for Genomic Research, 9712 Medical Center Drive, Rockville, MD 20850, USA. hkim@tigr.org
authors.forename: H Stanley
authors.initials: HS
authors.lastname: Kim
authors.forename: Mark A
authors.initials: MA
authors.lastname: Schell
authors.forename: Yan
authors.initials: Y
authors.lastname: Yu
authors.forename: Ricky L
authors.initials: RL
authors.lastname: Ulrich
authors.forename: Saul H
authors.initials: SH
authors.lastname: Sarria
authors.forename: William C
authors.initials: WC
authors.lastname: Nierman
authors.forename: David
authors.initials: D
authors.lastname: DeShazer
mesh_terms: D000818:Animals; D019117:Burkholderia / Q000166:cytology / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D019121:Burkholderia Infections / Q000473:pathology; D002470:Cell Survival; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D004269:DNA, Bacterial / Q000235:genetics; D016680:Genome, Bacterial; D008099:Liver / Q000382:microbiology; D051379:Mice; D009693:Nucleic Acid Hybridization; D013154:Spleen / Q000382:microbiology; D014774:Virulence / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial