The complete genome sequence of Francisella tularensis, the causative agent of tularemia.
Francisella tularensis is one of the most infectious human pathogens known. In the past, both the former Soviet Union and the US had programs to develop weapons containing the bacterium. We report the complete genome sequence of a highly virulent isolate of F. tularensis (1,892,819 bp). The sequence uncovers previously uncharacterized genes encoding type IV pili, a surface polysaccharide and iron-acquisition systems. Several virulence-associated genes were located in a putative pathogenicity island, which was duplicated in the genome. More than 10% of the putative coding sequences contained insertion-deletion or substitution mutations and seemed to be deteriorating. The genome is rich in IS elements, including IS630 Tc-1 mariner family transposons, which are not expected in a prokaryote. We used a computational method for predicting metabolic pathways and found an unexpectedly high proportion of disrupted pathways, explaining the fastidious nutritional requirements of the bacterium. The loss of biosynthetic pathways indicates that F. tularensis is an obligate host-dependent bacterium in its natural life cycle. Our results have implications for our understanding of how highly virulent human pathogens evolve and will expedite strategies to combat them.
Larsson
Pär
P
Swedish Defence Research Agency, SE-901 82 Umeå, Sweden.
Oyston
Petra C F
PC
Chain
Patrick
P
Chu
May C
MC
Duffield
Melanie
M
Fuxelius
Hans-Henrik
HH
Garcia
Emilio
E
Hälltorp
Greger
G
Johansson
Daniel
D
Isherwood
Karen E
KE
Karp
Peter D
PD
Larsson
Eva
E
Liu
Ying
Y
Michell
Stephen
S
Prior
Joann
J
Prior
Richard
R
Malfatti
Stephanie
S
Sjöstedt
Anders
A
Svensson
Kerstin
K
Thompson
Nick
N
Vergez
Lisa
L
Wagg
Jonathan K
JK
Wren
Brendan W
BW
Lindler
Luther E
LE
Andersson
Siv G E
SG
Forsman
Mats
M
Titball
Richard W
RW
D001483:Base Sequence; D004251:DNA Transposable Elements; D005604:Francisella tularensis / Q000235:genetics* / Q000254:growth & development; D016680:Genome, Bacterial; D044404:Genomic Islands; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D017422:Sequence Analysis, DNA; D014774:Virulence / Q000235:genetics
D004251:DNA Transposable Elements; D007501:Iron