ral
ssBioMed CentBMC Genomics
Open AcceResearch article
Virulence factor rtx in Legionella pneumophila, evidence suggesting 
it is a modular multifunctional protein
Giuseppe D'Auria1,2, Núria Jiménez1,2, Francesc Peris-Bondia1, 
Carmen Pelaz3, Amparo Latorre1,2 and Andrés Moya*1,2
Address: 1Instituto Cavanilles de Biodiversidad y Biologia Evolutiva, Universitat de València, Spain, 2CIBER en Epidemiología y Salud Pública 
(CIBERESP), Spain and 3National Centre of Microbiology, Institute of Health Carlos III, Majadahonda, Madrid, Spain
Email: Giuseppe D'Auria - giuseppe.dauria@uv.es; Núria Jiménez - nuria.jimenez@uv.es; Francesc Peris-Bondia - francisco.peris-bondia@uv.es; 
Carmen Pelaz - cpelaz@isciii.es; Amparo Latorre - amparo.latorre@uv.es; Andrés Moya* - andres.moya@uv.es
* Corresponding author    
Abstract
Background: The repeats in toxin (Rtx) are an important pathogenicity factor involved in host
cells invasion of Legionella pneumophila and other pathogenic bacteria. Its role in escaping the host
immune system and cytotoxic activity is well known. Its repeated motives and modularity make Rtx
a multifunctional factor in pathogenicity.
Results: The comparative analysis of rtx gene among 6 strains of L. pneumophila showed modularity
in their structures. Among compared genomes, the N-terminal region of the protein presents
highly dissimilar repeats with functionally similar domains. On the contrary, the C-terminal region
is maintained with a fashionable modular configuration, which gives support to its proposed role in
adhesion and pore formation. Despite the variability of rtx among the considered strains, the
flanking genes are maintained in synteny and similarity.
Conclusion: In contrast to the extracellular bacteria Vibrio cholerae, in which the rtx gene is highly
conserved and flanking genes have lost synteny and similarity, the gene region coding for the Rtx
toxin in the intracellular pathogen L. pneumophila shows a rapid evolution. Changes in the rtx could
play a role in pathogenicity. The interplay of the Rtx toxin with host membranes might lead to the
evolution of new variants that are able to escape host cell defences.
Background
Legionella pneumophila is a gram negative, gamma-proteo-
bacteria organism whose natural hosts are amoebae and
protozoa. This bacterium can infect humans by inhalation
of aerosols [1,2] entering alveolar macrophages causing
the well-known, and often lethal, Legionnaires' disease
(LD) or Legionellosis. Despite the great number of iso-
sis [3]. The first critical event during infection by L. pneu-
mophila involves the macrophages by the action of the
type IV secretion system, which prevents the fusion of the
phagosome with the lysosome and its acidification [4,5].
It has been demonstrated that these events start very early
after the infection [6]. Several mechanisms play an impor-
tant role in the formation of infection vacuoles. Legionella
Published: 14 January 2008
BMC Genomics 2008, 9:14 doi:10.1186/1471-2164-9-14
Received: 25 July 2007
Accepted: 14 January 2008
This article is available from: http://www.biomedcentral.com/1471-2164/9/14
© 2008 D'Auria et al; licensee BioMed Central Ltd. 
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), 
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Page 1 of 7
(page number not for citation purposes)
lates of L. pneumophila, the ones belonging to serogroup 1
are responsible of about 80 to 90% of cases of Legionello-
enters the macrophages by vacuoles that are morphologi-
cally similar to macropinosomes by an unusual mecha-
BMC Genomics 2008, 9:14 http://www.biomedcentral.com/1471-2164/9/14
nisms called "coiling phagocytosis" [6,7]. The vacuole is
immediately surrounded by vesicles and mitochondria
and moves toward the endoplasmic reticulum escaping or
delaying fusion with the lysosome [8]. At this stage, the
vacuoles offer a perfect niche for bacteria to multiply
safely away from the lysosome. Legionella is also able to
mediate the delayed entrance of the cell in apoptosis by
modulating the activity of caspase-3 and other effectors
[9,10]. In all these stages the Dot/Icm (Defective in
organelle trafficking/Intracellular multiplication) system,
involved in the formation of type IV secretor machinery,
is the main player acting on the transfer of a series of effec-
tors in the host cell [11-14].
One of the first events in the pathogenic cascade is pore
formation, which seems to be caused by a toxin belonging
to the Rtx family ("repeats-in toxin") [15]. It was demon-
strated that the rtxA gene in L. pneumophila is strictly
related to pathogenicity, and its main role involves adher-
ence to the host membranes, thus facilitating all the
molecular trafficking of the bacteria during infection proc-
esses [16]. In other bacteria like Bordetella pertussis,
Escherichia coli or Actinobacillus actinomycetemcomitans,
proteins belonging to the Rtx family are also described as
effectors of immune cell lyses and its action is often medi-
ated by specific host membrane receptors [17,18]. RtxA in
L. pneumophila is a large protein (around 7.000 amino
acids) with several repeated structures belonging to, at
least, three protein family domains. In L. pneumophila
strains Lens [GenBank:CR628337] and Paris [Gen-
Bank:CR628336] a correlation could exists between the
number of repeats and greater invasion and virulence
properties [19].
In this work, we analyse the mosaic structure of an RtxA
toxin from the highly virulent L. pneumophila strain 2300/
99. It was isolated in Alcoy (Spain) and was retrieved in
several outbreaks in 1999 and 2000, during which more
than 200 patients were infected, a dozen of whom died. In
all cases, transmission was due to aerosol inhalation from
out-door installations [20]. The comparative analysis of
the rtx locus of closely related L. pneumophila serogroup 1
strains showed the existence of a long tandem repeated
domain of variable copy number and sequence. Further-
more, we have studied similarity and gene-order conserva-
tion of genes flanking the rtx region, finding remarkably
high levels of rearrangements and diversity of the rtxA
gene as compared to those from flanking regions. This
pattern is completely opposite to that found in several
strains of Vibrio cholerae, a phylogenetically close extracel-
lular pathogen.
Results
rtx structure
Due to the difficulties given by the assembling of such a
large and repeated region, the number of repetitions, and
consequently, the protein length are approximate and
according to what have been published on each released
genome. Figure 1 shows the structure of rtx region among
the different Legionella strains and Table 1 is a summary of
the main structural characteristics. As it can be observed,
rtx genes vary in length. The corresponding ORFs are of
approximately 7910 aa, 7679 aa, 6289 aa and 4669 aa for
strains Lens, Paris Corby and Alcoy (present work),
respectively. In the case of the AA100 sequenced contig,
two ORFs were identified as previously described by
Cirillo et al. [21] (arpB and rtxA fused into one continuous
peptide). In the case of the Corby strain, in spite of the
high conservation of sequence structure and position of
flanking genes, it has been annotated as a "hypothetical
protein" and its arrangement is complementary and
reversed with respect to Paris, Lens and Philadelphia
strains. In L. pneumophila Philadelphia, the rtx gene is bro-
ken into two ORFs (lpg0644 and lpg0645) with an unan-
notated gap of about 2.600 nt in 3' with respect to the
lpg0644. The initial region of rtx gene is highly conserved
in the five strains (red bars in Figure 1). However, in the
strains analyzed in the present work, the region is fol-
lowed by a variable number of tandem repeats. The
repeats contain domains involved in host-membrane
interaction, with a wide variability either in copy number
and, surprisingly, in nucleotide composition (see Addi-
tional file 1). These repeats ranged from 549 nt in the
Paris strain to 460 nt in the Lens strain. In the Paris strain,
30 type a repeats were described, while in the Lens strain
two kinds of repeats, namely b1 and b2, were observed (as
reported also by Cazalet et al. [19]). Their sequences differ
rtx structures among the six compared genomesFigu e 1
rtx structures among the six compared genomes. 
Structure of the rtxA genes in the six Legionella genomes stud-
ied. Regions of the rtx are marked with correspondent col-Page 2 of 7
(page number not for citation purposes)
ours (see legend).
BMC Genomics 2008, 9:14 http://www.biomedcentral.com/1471-2164/9/14
completely, with 26 and 9 repetitions respectively and
with no possible alignment between them (Table 1; Addi-
tional file 1, section B). In the Corby strain, we distinguish
two different types of repeats, which can be aligned: four
named c1 and twenty-one named c2. In the Alcoy strain,
the first repeat spanning from position (nt) 1630 to 2117
is identical to c1 type, whereas the other 15 repeats are
almost identical to the c2 Corby type. Finally, 6 repeats of
type d were found in the Philadelphia strain. The Philadel-
phia repeats of the rtx gene were identified along and
ahead of the ORF lpg0644. Finally, in the case of the
AA100 strain, the analysed sequence was not covering the
C-terminal region containing the repeats, probably
because the studied fosmid insert did not contain the
region.
After searching in the PFAM database, several kinds of
adhesion related domains were identified as part of
repeats type a (Paris), b1 (Lens), c1 and c2 (Corby and
Alcoy). No domains related to adhesion were identified in
rtx gene of the Philadelphia strain, while only the c1 and
c2 repeats were phylogenetically related (see Additional
file 1). Therefore, the way we approached the modular
structure of the repeats was by looking at the function of
the domains involved in adhesion, with only one excep-
tion: the AA100 sequence which spans the region located
after the repeats, so it was not possible to include it in our
description.
In the four completed genomes (Paris, Lens, Philadelphia
and Corby) as well as in the contigs sequenced belonging
to the Alcoy and AA100 strains, a von Willebrand factor
type A domain (VWA) was identified, subsequent to the
regions with tandem repeats. In addition, several blocks of
tandem repeats identified as HemolysinCabind domains
were also found. These blocks were formed by a number
of different repeats: 3+2 repeats in Paris, 1+3+2 in Lens,
3+3+2 in Corby, 3+3+2 in Alcoy, 3+3+2 in Philadelphia
and 1+3+2 in AA100. The latter domain was previously
described and considered responsible for the virulent
activity of the RtxA protein [16,22-24]. A summary of all
these structural features of the rtx present in different
Legionella strains is shown in Table 1.
Comparative genomics and phylogenetic analyses
The Multi Locus Sequence Typing (MLST) analysis carried
out following the scheme suggested for L. pneumophila
serogroup 1 [25], using the information available for the
five genomes shows that Corby and Alcoy strains are close
related, while, due to the low bootstrap values, the posi-
tioning of an ancestor to these two strains is not univocal
(Figure 2). The whole genome alignments (data not
shown), indicate that the genome back-bone is generally
maintained with a high level of synteny. However, the
synteny surrounding the rtx region found in Legionella (see
Figure 3 and Additional file 2) has not been found in
other pathogenic strains. Thus, we performed the same
kind of alignment on Vibrio cholerae by choosing five rtx
genes from two complete genomes plus three partial shot-
gun contigs (see Material and Methods and Additional file
3). As it can be observed, there are slight differences in the
organization of rtx flanking genes (red shaded zones).
Moreover, contrary to what observed in Legionella, there is
a high level of conservation in the rtx region.
Table 1: rtxA structure summary. The columns report respectively: strain with accession number in parenthesis; GenBank locus tag 
used to identify the gene; length in aminoacids; number and types of repeat and number and kind of domains identified by PFAM 
search.
Strain Locus tag Length (aa)* Repeats* Domains at N-terminal region
Lens (CR628337) lpl0681 7910 26 (type b1), 9 (type b2) 26 Chlam_PMP
---
1 VWA
6 HemolysinCabind
Paris (CR628336) lpp0699 7679 30 (type a) 30 TSP_3
1 VWA
5 HemolysinCabind
Corby (CP000675) lpc2649 6289 4(type c1)
21(type c2)
25 HIM
1 VWA
8 HemolysinCabind
Alcoy (EU054322) lpa00614 4669 16 (type c) 16 HIM
1 VWA
8 HemolysinCabind
Philadelphia (AE017354) lpg0644
spacer
lpg0645
1487
865 (presumed)
681
3033 (total)
6 (type d) 1 VWA
8 HemolysinCabind
AA100 (AF057703) 1208 --- 1VWA
6 HemolysinCabindPage 3 of 7
(page number not for citation purposes)
*Length of proteins and number of repeats estimated according to the sequences published in relative Genome Project.
BMC Genomics 2008, 9:14 http://www.biomedcentral.com/1471-2164/9/14
Strains Corby and Alcoy, on the other hand, are quite sim-
ilar in their rtx gene at both protein domains and nucle-
otide level (Figure 1). Similarly to the other Legionella
genomes, flanking genes are highly conserved both in
order and orientation. N-terminal repeats are phylogenet-
ically closely related (see Additional file 1, section
C1+C2).
The alignment of repeated domains of the genomes con-
sidered here is practically impossible at nucleotide level,
and even at amino acid level it is very complicated. Addi-
tional file 4 shows the amino acid alignment for each kind
of repeat using CLUSTLALW and corrected by eye. The
domains identified by PFAM are highlighted. It is not pos-
sible to identify any phylogenetic relationships either
among the repeats or looking at the sole adhesion
domains.
Discussion
Here we report a comparative analysis of the Rtx toxin, as
well as a fine analysis of repeats, identified in this protein
in strains of L. pneumophila serogroup 1 from four com-
pleted genomes (strains Lens, Paris, Philadelphia and
Corby), one shotgun ongoing sequencing project (strain
Alcoy 2300/99) and one contig coming from a cosmid of
the Legionella strain AA100. All these strains are known to
be virulent [19,21,26,27].
The rtx genes analyzed in the six genomes studied, present
modularity. The toxin appears to be clearly divided in two
regions, the N-terminal, involved in adhesion, and the C-
terminal region, involved in adhesion and pore formation
in the host membranes. The repeats in the N-terminal
region analysed by PFAM database searches, have differ-
ent kinds of adhesion domains. In all the N-terminal type
a repeats of the Paris strain, similarity was found with the
"Thrombospondin type 3 repeat" (TSP_3) of the human
endothelial cell. In humans, this domain has been shown
to bind fibrinogen, fibronectin, laminin and type V colla-
gen [28,29]. In the Lens strain, repetitions of type b1 show
domains similar to the "Chlamydia polymorphic mem-
brane protein" (Chlam_PMP). This obligate intracellular
human pathogen causes infection of the upper and lower
respiratory tract but the role of this membrane protein is
still unknown [30]. No similarity with specific domains
was found for b2 type repeat of the Lens strain. The last
kind of repeat-associated domains, identified in type c1
and c2 of Alcoy and Corby strains, were similar to the
"Haemagglutinin" (HIM) domain that was found in inva-
sins and hemagglutinins, and is associated with the
Hep_Hag repeats [31].
Two other types of domains were commonly identified in
all the rtx genes: the VWA domain involved in adhesion
processes [32,33], and another tandem repeated domain
related to cytotoxic activity, the haemolysin calcium-bind-
ing (HemolysinCabind) site. The latter domain com-
monly brings a nonapeptide that is related to the
adhesion with other host cell surfaces or vacuole mem-
branes and pores formation [23,34].
Except for Alcoy and Corby, which are very similar, the N-
terminal repeats and their modular structure are highly
variable among strains. Despite these differences, the
flanking genes at 5' and 3' are highly conserved in
sequence and order, which suggests that rtx undergoes a
particular intra-genic evolution. Various examples of large
Plot of rtx region of Legionella strainsFigure 3
Plot of rtx region of Legionella strains. Comparative plot 
describing similarity between rtxA regions among five L. pneu-
mophila genomes. In pink are described regions sharing a 
nucleotide similarity higher than 70%. Green boxes represent 
gene positions and strand. Rtx 5' and 3' regions are shaded in 
red. For an easy visualization, the Corby sequence was com-
plemented and reversed. For a more detailed view see addi-
MLST phylogenetic treeFigure 2
MLST phylogenetic tree. Unrooted MLST tree. Numbers 
at node positions indicate bootstrap values greater than 50% 
(500 replicates).
Legionella pneumophila Alcoy
Legionella pneumophila Corby
Legionella pneumophila Paris
Legionella pneumophila Philadelphia
Legionella pneumophila Lens
100
54
0.002Page 4 of 7
(page number not for citation purposes)
non-interspaced repeats within CDS (Coding DNA
Sequences) regions were described in bacteria such as E.
tional file 2
BMC Genomics 2008, 9:14 http://www.biomedcentral.com/1471-2164/9/14
coli and Bacillus subtilis, where recombination events were
used to explain the distribution of large repeats among
genomes [26,35]. The case of rtx gene in L. pneumophila is
particularly interesting due to the high number of
observed intra-genic repeats. The origin of these repeats is
yet unknown, as no similar sequences (by BLAST
searches) have been identified in published data. As
described in gene conversion models, DNA can enter to
become part of a given gene [36] and afterwards, con-
certed evolution could be responsible for promoting the
different adhesion domains. In fact, although the repeats
type a, b, c, and d do not show any evolutionary relation-
ships, the presence of different adhesion domains points
towards a functional evolutionary advantage.
In V. cholerae the configuration of the rtx gene and its
flanking regions is extremely different from that observed
in L. pneumophila. Comparative analyses of rtx gene
among five strains show a high level of conservation and
the genes located at 5' of rtx, are strictly conserved, both in
sequence and order, whereas the synteny, and sometimes
nucleotide similarity, of those located at 3' do not follow
the same pattern (see Additional file 3).
Conclusion
In Legionella spp. it was previously thought that only
strains containing an active rtxA gene were able to produce
infection in humans, and that mutants with a frame-shift
inactivating rtxA protein were reduced for entry into host
cells and pore formation in host membranes [25]. rtxA
seems to play a relevant role in the pathogenic activity of
Legionella, although it also depends on the particular type
of host. The variety of repeats and its homogeneous nature
at rtxA N-terminal region of virulent strains of L. pneu-
mophila seems to be acquired by the two mechanisms
involved in concerted evolution: intra-genic gene conver-
sion and/or unequal crossing over. As previously
described for similar models in other organisms [36,37],
these mechanisms can be an important source of creating
antigenic variability in Legionella, affording the ability to
increase the host range and escape from the host's
immune defences.
Methods
Bacterial strains
L. pneumophila serogroup 1 strain (numbered as 2300/99)
was isolated from sputum of a patient with Legionnaires'
disease and associated to LD outbreak detected in Alcoy
(Alicante, Spain) in 1999, from hereinafter strain Alcoy.
DNA treatments library construction and sequencing
DNA from the L. pneumophila Alcoy was extracted as
described in Ausubel et al.[38] at "Centro Nacional de
ication for the construction of two libraries for inserts
ranging from 1 to 2 kb and from 2 to 10 kb. Fragments
were separated by "Pulsed Field Gel Electrophoresis"
applying following conditions: Voltage, 2 V/cm; initial
switch time, 0.1 s; final switch time, 1 s; temperature,
14°C; run time, 22 h; angle, 120°. After cutting bands out
for the corresponding sizes, DNA was recovered from aga-
rose by electroelution and subsequently purified by phe-
nol/chloroform purification. Ends of fragments were
flushed and tailed for TA cloning with "Single dA™ Tailing
Kit" (Novagen, #69282-3). After flushing and tailing,
DNA was precipitated with 2 Vol of ethanol 96% and 0.1
Vol of sodium acetate 3 M, and eluted in dH2O. Next, frag-
ments were cloned with "TOPO XL PCR Cloning Kit"
(Invitrogen, #K4700-10). Plasmid DNA purification was
done with a "Montage Plasmid Miniprep 96 kit" (Milli-
pore, #LSKP09624) in a "MULTIPROBE II-Robot Liquid
Handling System". Sequencing reactions were carried out
by the "ABI PRISM Big Dye Terminator v3.0 Ready Reac-
tion Cycle Sequencing Kit" (Applied Biosystems,
#4336919) and solved by the "3730XL Genetic Analyzer"
(Applied Biosystems).
Sequences analysis
Sequences used in this paper are: L. pneumophila strains
Paris [GenBank:CR628336], Lens [GenBank:CR628337],
Corby [GenBank:CP000675], Alcoy [Gen-
Bank:EU054322], Philadelphia [GenBank:AE017354],
AA100 [GenBank:AF057703]. Vibrio cholerae strains are:
O395 [GenBank:NC_009457], O1 biovar eltor strain
N16961 [GenBank:NC_002505], NCTC 8457 [Gen-
Bank:AAWD01000018], MZO-3 [Gen-
Bank:AAUU01000029] and MO10
[GenBank:DS179636].
The shotgun sequences assembly of the ongoing sequenc-
ing project of L. pneumophila Alcoy was carried out by the
"Staden Package release v1.6.0" [39]. ORF prediction of
the yet unfinished strain Alcoy was performed by the use
of "Glimmer 3" [40]. Sequence manipulation and anno-
tation was done with "Artemis" software [41]. Compara-
tive analyses were carried out by "BLAST" (Basic Local
Alignment Search Tool) suite [42] and the visualization of
the results obtained by means of the "ACT" (Artemis
Comparative Tool) [43]. Repetitions were identified by
the software "Tandem Repeats Finder" [44]. Finally,
domain identification was carried out using the PFAM
database [45].
MLST analysis
For this analysis we selected three house keeping genes
(acn, aconitate hydratase; groEL, 60 kDa chaperonin; recA,
DNA recombination protein) and three fast evolvingPage 5 of 7
(page number not for citation purposes)
Microbiología del Instituto de Salud Carlos III (Majada-
honda, Madrid, Spain)". Briefly, DNA was sheared by son-
genes (flaA, flagellin; proA, zinc metalloprotease; mompS,
major outer membrane protein) [25]. The nucleotide
BMC Genomics 2008, 9:14 http://www.biomedcentral.com/1471-2164/9/14
sequences of each gene were concatenated and a tree
based on Maximum Likelihood using Transition-Trans-
version plus Gamma substitution (as suggested by Model-
Test analysis [46]) was obtained by the MEGA3.1 [47]
software. Reliability of the monophyletic groups was
tested by a bootstrap test with 500 replicates.
Alcoy strain accession numbers
The genome project of Legionella pneumophila 2300/99
Alcoy is maintained at NCBI with project ID 18743. The
new Alcoy sequences used in this work are available in
GenBank: rtx gene contig, accession number EU054322.
The genes used for MLST analysis have the following
accession numbers: EU221241 (acn), EU221242 (flaA),
EU221243 (groEL), EU221244 (mompS), EU221245
(proA), EU221246 (recA).
Authors' contributions
GD participated in conception, genome assembly/study
and drafted the manuscript. NJ and FPB participated in
sequencing and genome assembly. CP maintained the
studied strain and provided genomic DNA for the pro-
posed work. AL participated in the conception and design
of the study and critically revised the manuscript. AM par-
ticipated in the conception and design of the study and
critically revised the manuscript. All authors have read
and approved the final manuscript.
Additional material
Acknowledgements
This work has been funded by grant BMC2006-06003 from MEC to AL and 
by contract with Conselleria de Sanidad of Valencian Government to AM. 
Nuria Jiménez is recipient of a fellowship from Carlos III and Giuseppe 
D'Auria has a research contract from CIBERESP. Sequencing was carried 
out using facilities of the SCSIE from University of Valencia.
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Additional file 1
Nucleotide alignment of repeats. Alignment of each repeats from each 
genome analysed. The name of each sequence start with "rep" followed by 
three letters indicating the strain: lpp, lpl, lpc, lpa, lpg respectively for 
Paris, Lens, Corby, Alcoy and Philadelphia strains. For each repetition, 
after the name of the strain is reported the nucleotide position in the 
respective rtxA protein. "." indicate identical positions; "~" indicates gaps 
in the alignment. Gray background represents PFAM recognized domains 
with respective definitions.
Click here for file
[http://www.biomedcentral.com/content/supplementary/1471-
2164-9-14-S1.DOC]
Additional file 2
Detailed plot of rtx region of Legionella strains. Comparative plot 
describing similarity between rtxA regions among the five L. pneu-
mophila genomes. In pink are described regions sharing a nucleotide sim-
ilarity higher than 70%. Green boxes represent gene positions and strand. 
Chromosome relative positions are reported for each genome in the central 
strip. Rtx 5' and 3' regions are shaded in red. For an easy visualization, 
the Corby sequence was complemented and reversed.
Click here for file
[http://www.biomedcentral.com/content/supplementary/1471-
2164-9-14-S2.PPT]
Additional file 3
Detailed plot of rtx region of Vibrio strains. Comparative plot describ-
ing similarity between rtxA regions among the five Vibrio cholerae 
genomes reported in the text. In pink are described regions sharing a 
nucleotide similarity higher than 70%. Green boxes represent gene posi-
tion and strand. Chromosome relative positions are reported for each 
genome in the central strip. Red shadows highlight 5' and 3' flanking 
regions. Gene names or locus tags are reported for each gene.
Click here for file
[http://www.biomedcentral.com/content/supplementary/1471-
2164-9-14-S3.PPT]
Additional file 4
Aminoacids alignment of repeats. Aminoacids alignment of each kind of 
repeats. The alignment was obtained by CLUSTALW and corrected by 
eye. On the left side the name of strain and type of repeat is reported. "~" 
indicates gaps in the alignment. Colour shaded regions represents 
domains identified by PFAM searches.
Click here for file
[http://www.biomedcentral.com/content/supplementary/1471-
2164-9-14-S4.DOC]Page 6 of 7
(page number not for citation purposes)
plete activation of macrophage apoptosis during intracellu-
lar replication of Legionella pneumophila.  Infect Immun 2005,
73:5339-5349.
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glanders but not human melioidosis.  BMC Microbiol 2007, 7:19.