Limits...
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.

Show MeSH

Related in: MedlinePlus

Genomic organization of the scpB-lmb intergenic region.Dark grey box represents the noncoding spacer region. Primer set scpB3382/rlmb51 was used to determine the structure of the scpB-lmb intergenic region. The presence of the insertion sequence IS1548 and of the group II intron GBSi1 in the spacer was then confirmed using primer sets scpB3382/r1S1548, and scpB3382/rGBSi143.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2875397&req=5

pone-0010794-g001: Genomic organization of the scpB-lmb intergenic region.Dark grey box represents the noncoding spacer region. Primer set scpB3382/rlmb51 was used to determine the structure of the scpB-lmb intergenic region. The presence of the insertion sequence IS1548 and of the group II intron GBSi1 in the spacer was then confirmed using primer sets scpB3382/r1S1548, and scpB3382/rGBSi143.

Mentions: Genes encoding the surface proteins ScpB and Lmb are located on a composite transposon [14]. Three different structures of the scpB-lmb intergenic region are described (Fig. 1) since this region appears to be a hot spot for integration that may contain the two types of MGEs above-mentioned, GBSi1 or IS1548 [13], [15], [16], [17], [18]. GBSi1 and IS1548 are located 97-bp upstream and 9-bp upstream of the putative promoter of the lmb gene, respectively [17]. In addition to cleavage of the chemotactic complement component C5a, ScpB mediates GBS binding to human immobilized fibronectin, a large dimeric glycoprotein present in the extracellular matrix in a fibrillar form [19]; ScpB also plays a role in the invasion of GBS into epithelial cells [20], and an induced transcription of scpB by components of human serum has recently been reported [21]. Binding of GBS to human laminin, a major glycoprotein of the basement membrane [22], is mediated by the surface-associated lipoprotein Lmb (laminin-binding protein) [23]. Lmb shows homology to members of the LraI family that includes Lsp/Lbp of Streptococcus pyogenes [23], [24], [25] and it promotes GBS invasion into human brain microvascular endothelial cells [26]. It has not been explored yet if the presence of MGEs in scpB-lmb intergenic region correlates with particular levels of transcription and expression of lmb and scpB genes.


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)

Genomic organization of the scpB-lmb intergenic region.Dark grey box represents the noncoding spacer region. Primer set scpB3382/rlmb51 was used to determine the structure of the scpB-lmb intergenic region. The presence of the insertion sequence IS1548 and of the group II intron GBSi1 in the spacer was then confirmed using primer sets scpB3382/r1S1548, and scpB3382/rGBSi143.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0010794-g001: Genomic organization of the scpB-lmb intergenic region.Dark grey box represents the noncoding spacer region. Primer set scpB3382/rlmb51 was used to determine the structure of the scpB-lmb intergenic region. The presence of the insertion sequence IS1548 and of the group II intron GBSi1 in the spacer was then confirmed using primer sets scpB3382/r1S1548, and scpB3382/rGBSi143.
Mentions: Genes encoding the surface proteins ScpB and Lmb are located on a composite transposon [14]. Three different structures of the scpB-lmb intergenic region are described (Fig. 1) since this region appears to be a hot spot for integration that may contain the two types of MGEs above-mentioned, GBSi1 or IS1548 [13], [15], [16], [17], [18]. GBSi1 and IS1548 are located 97-bp upstream and 9-bp upstream of the putative promoter of the lmb gene, respectively [17]. In addition to cleavage of the chemotactic complement component C5a, ScpB mediates GBS binding to human immobilized fibronectin, a large dimeric glycoprotein present in the extracellular matrix in a fibrillar form [19]; ScpB also plays a role in the invasion of GBS into epithelial cells [20], and an induced transcription of scpB by components of human serum has recently been reported [21]. Binding of GBS to human laminin, a major glycoprotein of the basement membrane [22], is mediated by the surface-associated lipoprotein Lmb (laminin-binding protein) [23]. Lmb shows homology to members of the LraI family that includes Lsp/Lbp of Streptococcus pyogenes [23], [24], [25] and it promotes GBS invasion into human brain microvascular endothelial cells [26]. It has not been explored yet if the presence of MGEs in scpB-lmb intergenic region correlates with particular levels of transcription and expression of lmb and scpB genes.

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