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Enhanced expression of lmb gene encoding laminin-binding protein in Streptococcus agalactiae strains harboring IS1548 in scpB-lmb intergenic region.

Al Safadi R, Amor S, Hery-Arnaud G, Spellerberg B, Lanotte P, Mereghetti L, Gannier F, Quentin R, Rosenau A - PLoS ONE (2010)

Bottom Line: IS1548 was mostly found (72.2%) in CC19 serotype III strains recovered more specifically (92.3%) from neonatal meningitis.No MGE was found in most strains of the other CCs (76.0%), notably CC23, CC10 and CC1.Deletion of the IS1548 sequence between scpB and lmb genes in a CC19 serotype III GBS strain substantially reduced the transcription of lmb gene (13.5-fold), the binding ability to laminin (6.2-fold), and the expression of Lmb protein (5.0-fold).

View Article: PubMed Central - PubMed

Affiliation: Equipe d'Accueil 3854 Bactéries et Risque Materno-Foetal, Institut Fédératif de Recherche 136 Agents Transmissibles et Infectiologie, UFR Médecine, Université François Rabelais de Tours, Tours, France.

ABSTRACT
Group B streptococcus (GBS) is the main cause of neonatal sepsis and meningitis. Bacterial surface proteins play a major role in GBS binding to and invasion of different host surfaces. The scpB and lmb genes, coding for fibronectin-binding and laminin-binding surface proteins, are present in almost all human GBS isolates. The scpB-lmb intergenic region is a hot spot for integration of two mobile genetic elements (MGEs): the insertion element IS1548 or the group II intron GBSi1. We studied the structure of scpB-lmb intergenic region in 111 GBS isolates belonging to the intraspecies major clonal complexes (CCs). IS1548 was mostly found (72.2%) in CC19 serotype III strains recovered more specifically (92.3%) from neonatal meningitis. GBSi1 was principally found (70.6%) in CC17 strains, mostly (94.4%) of serotype III, but also (15.7%) in CC19 strains, mostly (87.5%) of serotype II. No MGE was found in most strains of the other CCs (76.0%), notably CC23, CC10 and CC1. Twenty-six strains representing these three genetic configurations were selected to investigate the transcription and expression levels of scpB and lmb genes. Quantitative RT-PCR showed that lmb transcripts were 5.0- to 9.6-fold higher in the group of strains with IS1548 than in the other two groups of strains (P<0.001). Accordingly, the binding ability to laminin was 3.8- to 6.6-fold higher in these strains (P< or =0.001). Moreover, Lmb amount expressed on the cell surface was 2.4- to 2.7-fold greater in these strains (P<0.001). By contrast, scpB transcript levels and fibronectin binding ability were similar in the three groups of strains. Deletion of the IS1548 sequence between scpB and lmb genes in a CC19 serotype III GBS strain substantially reduced the transcription of lmb gene (13.5-fold), the binding ability to laminin (6.2-fold), and the expression of Lmb protein (5.0-fold). These data highlight the importance of MGEs in bacterial virulence and demonstrate the up-regulation of lmb gene by IS1548; the increased lmb gene expression observed in CC19 serotype III strains with IS1548 may play a role in their ability to cause neonatal meningitis and endocarditis.

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Expression of Lmb protein on GBS cells in relation to the scpB-lmb intergenic region structure.Lmb protein was quantified in an ELISA-type assay. GBS cells (8 strains without MGE, 9 strains with GBSi1, 9 strains with IS1548), were immobilized in microtiter wells and incubated with rabbit anti-Lmb antibodies. Binding of antibodies to the Lmb protein was quantified by addition of peroxidase-conjugated goat anti-rabbit IgG, and subsequent addition of OPD peroxidase substrate. Boxes are means and bars are standard deviation of the means of the absorbance at 492 nm (A492) per adhering bacteria in each group of strains. ** The amount of Lmb protein was significantly higher in the group of strains with IS1548 as compared with the other two groups of strains (P<0.001).
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pone-0010794-g003: Expression of Lmb protein on GBS cells in relation to the scpB-lmb intergenic region structure.Lmb protein was quantified in an ELISA-type assay. GBS cells (8 strains without MGE, 9 strains with GBSi1, 9 strains with IS1548), were immobilized in microtiter wells and incubated with rabbit anti-Lmb antibodies. Binding of antibodies to the Lmb protein was quantified by addition of peroxidase-conjugated goat anti-rabbit IgG, and subsequent addition of OPD peroxidase substrate. Boxes are means and bars are standard deviation of the means of the absorbance at 492 nm (A492) per adhering bacteria in each group of strains. ** The amount of Lmb protein was significantly higher in the group of strains with IS1548 as compared with the other two groups of strains (P<0.001).

Mentions: Lmb protein expressed at the bacterial cell surface was quantified in an ELISA-type assay, as described in Figure 3.


Enhanced expression of lmb gene encoding laminin-binding protein in Streptococcus agalactiae strains harboring IS1548 in scpB-lmb intergenic region.

Al Safadi R, Amor S, Hery-Arnaud G, Spellerberg B, Lanotte P, Mereghetti L, Gannier F, Quentin R, Rosenau A - PLoS ONE (2010)

Expression of Lmb protein on GBS cells in relation to the scpB-lmb intergenic region structure.Lmb protein was quantified in an ELISA-type assay. GBS cells (8 strains without MGE, 9 strains with GBSi1, 9 strains with IS1548), were immobilized in microtiter wells and incubated with rabbit anti-Lmb antibodies. Binding of antibodies to the Lmb protein was quantified by addition of peroxidase-conjugated goat anti-rabbit IgG, and subsequent addition of OPD peroxidase substrate. Boxes are means and bars are standard deviation of the means of the absorbance at 492 nm (A492) per adhering bacteria in each group of strains. ** The amount of Lmb protein was significantly higher in the group of strains with IS1548 as compared with the other two groups of strains (P<0.001).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2875397&req=5

pone-0010794-g003: Expression of Lmb protein on GBS cells in relation to the scpB-lmb intergenic region structure.Lmb protein was quantified in an ELISA-type assay. GBS cells (8 strains without MGE, 9 strains with GBSi1, 9 strains with IS1548), were immobilized in microtiter wells and incubated with rabbit anti-Lmb antibodies. Binding of antibodies to the Lmb protein was quantified by addition of peroxidase-conjugated goat anti-rabbit IgG, and subsequent addition of OPD peroxidase substrate. Boxes are means and bars are standard deviation of the means of the absorbance at 492 nm (A492) per adhering bacteria in each group of strains. ** The amount of Lmb protein was significantly higher in the group of strains with IS1548 as compared with the other two groups of strains (P<0.001).
Mentions: Lmb protein expressed at the bacterial cell surface was quantified in an ELISA-type assay, as described in Figure 3.

Bottom Line: IS1548 was mostly found (72.2%) in CC19 serotype III strains recovered more specifically (92.3%) from neonatal meningitis.No MGE was found in most strains of the other CCs (76.0%), notably CC23, CC10 and CC1.Deletion of the IS1548 sequence between scpB and lmb genes in a CC19 serotype III GBS strain substantially reduced the transcription of lmb gene (13.5-fold), the binding ability to laminin (6.2-fold), and the expression of Lmb protein (5.0-fold).

View Article: PubMed Central - PubMed

Affiliation: Equipe d'Accueil 3854 Bactéries et Risque Materno-Foetal, Institut Fédératif de Recherche 136 Agents Transmissibles et Infectiologie, UFR Médecine, Université François Rabelais de Tours, Tours, France.

ABSTRACT
Group B streptococcus (GBS) is the main cause of neonatal sepsis and meningitis. Bacterial surface proteins play a major role in GBS binding to and invasion of different host surfaces. The scpB and lmb genes, coding for fibronectin-binding and laminin-binding surface proteins, are present in almost all human GBS isolates. The scpB-lmb intergenic region is a hot spot for integration of two mobile genetic elements (MGEs): the insertion element IS1548 or the group II intron GBSi1. We studied the structure of scpB-lmb intergenic region in 111 GBS isolates belonging to the intraspecies major clonal complexes (CCs). IS1548 was mostly found (72.2%) in CC19 serotype III strains recovered more specifically (92.3%) from neonatal meningitis. GBSi1 was principally found (70.6%) in CC17 strains, mostly (94.4%) of serotype III, but also (15.7%) in CC19 strains, mostly (87.5%) of serotype II. No MGE was found in most strains of the other CCs (76.0%), notably CC23, CC10 and CC1. Twenty-six strains representing these three genetic configurations were selected to investigate the transcription and expression levels of scpB and lmb genes. Quantitative RT-PCR showed that lmb transcripts were 5.0- to 9.6-fold higher in the group of strains with IS1548 than in the other two groups of strains (P<0.001). Accordingly, the binding ability to laminin was 3.8- to 6.6-fold higher in these strains (P< or =0.001). Moreover, Lmb amount expressed on the cell surface was 2.4- to 2.7-fold greater in these strains (P<0.001). By contrast, scpB transcript levels and fibronectin binding ability were similar in the three groups of strains. Deletion of the IS1548 sequence between scpB and lmb genes in a CC19 serotype III GBS strain substantially reduced the transcription of lmb gene (13.5-fold), the binding ability to laminin (6.2-fold), and the expression of Lmb protein (5.0-fold). These data highlight the importance of MGEs in bacterial virulence and demonstrate the up-regulation of lmb gene by IS1548; the increased lmb gene expression observed in CC19 serotype III strains with IS1548 may play a role in their ability to cause neonatal meningitis and endocarditis.

Show MeSH
Related in: MedlinePlus