Virulence factor rtx in Legionella pneumophila, evidence suggesting it is a modular multifunctional protein.
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.


CONCLUSIONS
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.
D'Auria
Giuseppe
G
Instituto Cavanilles de Biodiversidad y Biologia Evolutiva, Universitat de València, Spain. giuseppe.dauria@uv.es
Jiménez
Núria
N
Peris-Bondia
Francesc
F
Pelaz
Carmen
C
Latorre
Amparo
A
Moya
Andrés
A
D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism; D005798:Genes, Bacterial; D006801:Humans; D016952:Legionella pneumophila / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D014774:Virulence; D037521:Virulence Factors / Q000737:chemistry / Q000502:physiology*
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D037521:Virulence Factors