Genomic islands from five strains of Burkholderia pseudomallei.
BACKGROUND
Burkholderia pseudomallei is the etiologic agent of melioidosis, a significant cause of morbidity and mortality where this infection is endemic. Genomic differences among strains of B. pseudomallei are predicted to be one of the major causes of the diverse clinical manifestations observed among patients with melioidosis. The purpose of this study was to examine the role of genomic islands (GIs) as sources of genomic diversity in this species.


RESULTS
We found that genomic islands (GIs) vary greatly among B. pseudomallei strains. We identified 71 distinct GIs from the genome sequences of five reference strains of B. pseudomallei: K96243, 1710b, 1106a, MSHR668, and MSHR305. The genomic positions of these GIs are not random, as many of them are associated with tRNA gene loci. In particular, the 3' end sequences of tRNA genes are predicted to be involved in the integration of GIs. We propose the term "tRNA-mediated site-specific recombination" (tRNA-SSR) for this mechanism. In addition, we provide a GI nomenclature that is based upon integration hotspots identified here or previously described.


CONCLUSIONS
Our data suggest that acquisition of GIs is one of the major sources of genomic diversity within B. pseudomallei and the molecular mechanisms that facilitate horizontally-acquired GIs are common across multiple strains of B. pseudomallei. The differential presence of the 71 GIs across multiple strains demonstrates the importance of these mobile elements for shaping the genetic composition of individual strains and populations within this bacterial species.
Tuanyok
Apichai
A
Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011-5640, USA. Apichai.Tuanyok@nau.edu
Leadem
Benjamin R
BR
Auerbach
Raymond K
RK
Beckstrom-Sternberg
Stephen M
SM
Beckstrom-Sternberg
James S
JS
Mayo
Mark
M
Wuthiekanun
Vanaporn
V
Brettin
Thomas S
TS
Nierman
William C
WC
Peacock
Sharon J
SJ
Currie
Bart J
BJ
Wagner
David M
DM
Keim
Paul
P
D042726:Burkholderia mallei / Q000235:genetics*; D022761:Gene Transfer, Horizontal; D014644:Genetic Variation; D044404:Genomic Islands; D012343:RNA, Transfer / Q000235:genetics; D009626:Terminology as Topic
D012343:RNA, Transfer