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Genome sequence and phenotypic analysis of a first German Francisella sp. isolate (W12-1067) not belonging to the species Francisella tularensis.

Rydzewski K, Schulz T, Brzuszkiewicz E, Holland G, Lück C, Fleischer J, Grunow R, Heuner K - BMC Microbiol. (2014)

Bottom Line: Isolate W12-1067 is closely related to the recently described F. guangzhouensis species and it replicates within eukaryotic host cells.Since W12-1067 exhibits a putative new type-VI secretion system and F. tularensis subsp. holarctica was found not to be the sole species in Germany, the new isolate is an interesting species to be analyzed in more detail.Further research is needed to investigate the epidemiology, ecology and pathogenicity of Francisella species present in Germany.

View Article: PubMed Central - HTML - PubMed

Affiliation: Cellular Interactions of Bacterial Pathogens, Centre for Biological Threats and Special Pathogens, Division 2 (ZBS 2), Robert Koch Institute, Nordufer 20, Berlin 13353, Germany. heunerk@rki.de.

ABSTRACT

Background: Francisella isolates from patients suffering from tularemia in Germany are generally strains of the species F. tularensis subsp. holarctica. To our knowledge, no other Francisella species are known for Germany. Recently, a new Francisella species could be isolated from a water reservoir of a cooling tower in Germany.

Results: We identified a Francisella sp. (isolate W12-1067) whose 16S rDNA is 99% identical to the respective nucleotide sequence of the recently published strain F. guangzhouensis. The overall sequence identity of the fopA, gyrA, rpoA, groEL, sdhA and dnaK genes is only 89%, indicating that strain W12-1067 is not identical to F. guangzhouensis. W12-1067 was isolated from a water reservoir of a cooling tower of a hospital in Germany. The growth optimum of the isolate is approximately 30°C, it can grow in the presence of 4-5% NaCl (halotolerant) and is able to grow without additional cysteine within the medium. The strain was able to replicate within a mouse-derived macrophage-like cell line. The whole genome of the strain was sequenced (~1.7 mbp, 32.2% G + C content) and the draft genome was annotated. Various virulence genes common to the genus Francisella are present, but the Francisella pathogenicity island (FPI) is missing. However, another putative type-VI secretion system is present within the genome of strain W12-1067.

Conclusions: Isolate W12-1067 is closely related to the recently described F. guangzhouensis species and it replicates within eukaryotic host cells. Since W12-1067 exhibits a putative new type-VI secretion system and F. tularensis subsp. holarctica was found not to be the sole species in Germany, the new isolate is an interesting species to be analyzed in more detail. Further research is needed to investigate the epidemiology, ecology and pathogenicity of Francisella species present in Germany.

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Genetic organization of T6 secretion systems in Francisella. Organization of the FPI island of Ft. novicida U112 (A) and of genomic islands I (B) and II (C) encoding putative T6-like secretion systems of Francisella isolate W12-1067. Genomic island I is integrated between genes pyrD and tyrA in W12-1067 and Ft. novicida U112, whereas it is integrated between F7308_1884 und F7308_1920 in Francisella strain TX077308 (F-TX077308). Genomic island II is integrated between rpsU and glmS in W12-1067 and is not present in Ft. novicida U112 and Francisella strain TX077308. Genes (ORFs) are indicated by arrows. Gene names are given below the genes, and the protein-encoding gene (peg) numbers are given in Table 5. Genes encoding homologous proteins are boxed in the same color, with the exception of pink (mobile elements) and black (conserved core genome genes).
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Figure 5: Genetic organization of T6 secretion systems in Francisella. Organization of the FPI island of Ft. novicida U112 (A) and of genomic islands I (B) and II (C) encoding putative T6-like secretion systems of Francisella isolate W12-1067. Genomic island I is integrated between genes pyrD and tyrA in W12-1067 and Ft. novicida U112, whereas it is integrated between F7308_1884 und F7308_1920 in Francisella strain TX077308 (F-TX077308). Genomic island II is integrated between rpsU and glmS in W12-1067 and is not present in Ft. novicida U112 and Francisella strain TX077308. Genes (ORFs) are indicated by arrows. Gene names are given below the genes, and the protein-encoding gene (peg) numbers are given in Table 5. Genes encoding homologous proteins are boxed in the same color, with the exception of pink (mobile elements) and black (conserved core genome genes).

Mentions: Francisella strains exhibit an FPI encoding a functional T6SS, needed for preventing phagolysosomal fusion and escape into the cytosol, which is therefore essential for intracellular replication and pathogenicity of Francisella[59-63]. The island is ~33 kb in length, encodes for 15–19 open reading frames (ORFs) and is present in Ft. tularensis strains, Ft. novicida and F. philomiragia (Figure 5A). In strains of F. tularensis this island is duplicated [36,64-66]. However, it is still unclear yet whether both copies are needed for full virulence of these strains. Genes of the locus were named igl (intracellular growth locus, [66]) and pdp (pathogenicity determinant proteins, [65]). The complete locus was identified in 2004, and it seems to be acquired via horizontal gene transfer because of a lower G + C content compared with the core genome [60,64,65].


Genome sequence and phenotypic analysis of a first German Francisella sp. isolate (W12-1067) not belonging to the species Francisella tularensis.

Rydzewski K, Schulz T, Brzuszkiewicz E, Holland G, Lück C, Fleischer J, Grunow R, Heuner K - BMC Microbiol. (2014)

Genetic organization of T6 secretion systems in Francisella. Organization of the FPI island of Ft. novicida U112 (A) and of genomic islands I (B) and II (C) encoding putative T6-like secretion systems of Francisella isolate W12-1067. Genomic island I is integrated between genes pyrD and tyrA in W12-1067 and Ft. novicida U112, whereas it is integrated between F7308_1884 und F7308_1920 in Francisella strain TX077308 (F-TX077308). Genomic island II is integrated between rpsU and glmS in W12-1067 and is not present in Ft. novicida U112 and Francisella strain TX077308. Genes (ORFs) are indicated by arrows. Gene names are given below the genes, and the protein-encoding gene (peg) numbers are given in Table 5. Genes encoding homologous proteins are boxed in the same color, with the exception of pink (mobile elements) and black (conserved core genome genes).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4230796&req=5

Figure 5: Genetic organization of T6 secretion systems in Francisella. Organization of the FPI island of Ft. novicida U112 (A) and of genomic islands I (B) and II (C) encoding putative T6-like secretion systems of Francisella isolate W12-1067. Genomic island I is integrated between genes pyrD and tyrA in W12-1067 and Ft. novicida U112, whereas it is integrated between F7308_1884 und F7308_1920 in Francisella strain TX077308 (F-TX077308). Genomic island II is integrated between rpsU and glmS in W12-1067 and is not present in Ft. novicida U112 and Francisella strain TX077308. Genes (ORFs) are indicated by arrows. Gene names are given below the genes, and the protein-encoding gene (peg) numbers are given in Table 5. Genes encoding homologous proteins are boxed in the same color, with the exception of pink (mobile elements) and black (conserved core genome genes).
Mentions: Francisella strains exhibit an FPI encoding a functional T6SS, needed for preventing phagolysosomal fusion and escape into the cytosol, which is therefore essential for intracellular replication and pathogenicity of Francisella[59-63]. The island is ~33 kb in length, encodes for 15–19 open reading frames (ORFs) and is present in Ft. tularensis strains, Ft. novicida and F. philomiragia (Figure 5A). In strains of F. tularensis this island is duplicated [36,64-66]. However, it is still unclear yet whether both copies are needed for full virulence of these strains. Genes of the locus were named igl (intracellular growth locus, [66]) and pdp (pathogenicity determinant proteins, [65]). The complete locus was identified in 2004, and it seems to be acquired via horizontal gene transfer because of a lower G + C content compared with the core genome [60,64,65].

Bottom Line: Isolate W12-1067 is closely related to the recently described F. guangzhouensis species and it replicates within eukaryotic host cells.Since W12-1067 exhibits a putative new type-VI secretion system and F. tularensis subsp. holarctica was found not to be the sole species in Germany, the new isolate is an interesting species to be analyzed in more detail.Further research is needed to investigate the epidemiology, ecology and pathogenicity of Francisella species present in Germany.

View Article: PubMed Central - HTML - PubMed

Affiliation: Cellular Interactions of Bacterial Pathogens, Centre for Biological Threats and Special Pathogens, Division 2 (ZBS 2), Robert Koch Institute, Nordufer 20, Berlin 13353, Germany. heunerk@rki.de.

ABSTRACT

Background: Francisella isolates from patients suffering from tularemia in Germany are generally strains of the species F. tularensis subsp. holarctica. To our knowledge, no other Francisella species are known for Germany. Recently, a new Francisella species could be isolated from a water reservoir of a cooling tower in Germany.

Results: We identified a Francisella sp. (isolate W12-1067) whose 16S rDNA is 99% identical to the respective nucleotide sequence of the recently published strain F. guangzhouensis. The overall sequence identity of the fopA, gyrA, rpoA, groEL, sdhA and dnaK genes is only 89%, indicating that strain W12-1067 is not identical to F. guangzhouensis. W12-1067 was isolated from a water reservoir of a cooling tower of a hospital in Germany. The growth optimum of the isolate is approximately 30°C, it can grow in the presence of 4-5% NaCl (halotolerant) and is able to grow without additional cysteine within the medium. The strain was able to replicate within a mouse-derived macrophage-like cell line. The whole genome of the strain was sequenced (~1.7 mbp, 32.2% G + C content) and the draft genome was annotated. Various virulence genes common to the genus Francisella are present, but the Francisella pathogenicity island (FPI) is missing. However, another putative type-VI secretion system is present within the genome of strain W12-1067.

Conclusions: Isolate W12-1067 is closely related to the recently described F. guangzhouensis species and it replicates within eukaryotic host cells. Since W12-1067 exhibits a putative new type-VI secretion system and F. tularensis subsp. holarctica was found not to be the sole species in Germany, the new isolate is an interesting species to be analyzed in more detail. Further research is needed to investigate the epidemiology, ecology and pathogenicity of Francisella species present in Germany.

Show MeSH
Related in: MedlinePlus