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Streptococcus pneumoniae detects and responds to foreign bacterial peptide fragments in its environment.

Hathaway LJ, Bättig P, Reber S, Rotzetter JU, Aebi S, Hauser C, Heller M, Kadioglu A, Mühlemann K - Open Biol (2014)

Bottom Line: AliB-like ORF 1 binds specifically peptide SETTFGRDFN, matching 50S ribosomal subunit protein L4 of Enterobacteriaceae, and facilitates upregulation of competence for genetic transformation.We found that AliB-like ORF 2 mediates the early phase of nasopharyngeal colonization in vivo.These findings reveal a completely new concept of pneumococcal interspecies communication which may have implications for communication between other bacterial species and for future interventional therapeutics.

View Article: PubMed Central - PubMed

Affiliation: Institute for Infectious Diseases, University of Bern, Bern, Switzerland.

ABSTRACT
Streptococcus pneumoniae is an important cause of bacterial meningitis and pneumonia but usually colonizes the human nasopharynx harmlessly. As this niche is simultaneously populated by other bacterial species, we looked for a role and pathway of communication between pneumococci and other species. This paper shows that two proteins of non-encapsulated S. pneumoniae, AliB-like ORF 1 and ORF 2, bind specifically to peptides matching other species resulting in changes in the pneumococci. AliB-like ORF 1 binds specifically peptide SETTFGRDFN, matching 50S ribosomal subunit protein L4 of Enterobacteriaceae, and facilitates upregulation of competence for genetic transformation. AliB-like ORF 2 binds specifically peptides containing sequence FPPQS, matching proteins of Prevotella species common in healthy human nasopharyngeal microbiota. We found that AliB-like ORF 2 mediates the early phase of nasopharyngeal colonization in vivo. The ability of S. pneumoniae to bind and respond to peptides of other bacterial species occupying the same host niche may play a key role in adaptation to its environment and in interspecies communication. These findings reveal a completely new concept of pneumococcal interspecies communication which may have implications for communication between other bacterial species and for future interventional therapeutics.

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Competence gene expression and transformation. (a) Percentage transformation rates of strain 110.58 and its mutants ΔORF 1 + 2, ΔORF 1 and ΔORF 2, showing the mean of three independent experiments. Error bars show s.e.m. *p = 0.0058, **p = 0.0022, ***p < 0.0001. (b) The synergistic effect of pre-incubation with 100 µg ml−1 AliB-like ORF 1 ligand (SETTFGRDFN) on CSP 2-mediated competence induction was determined by measuring the expression of late competence gene ssbB using a transcriptional fusion of the ssbB promoter region with the luciferase gene, displayed as AUC of the luminescence signal. Results represent three experiments and show s.e.m. For each strain, the expression of ssbB in the presence of ORF 1 ligand is presented as a fold difference compared with the expression value of that strain in the absence of the ORF 1 ligand. *p = 0.0311.
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RSOB130224F3: Competence gene expression and transformation. (a) Percentage transformation rates of strain 110.58 and its mutants ΔORF 1 + 2, ΔORF 1 and ΔORF 2, showing the mean of three independent experiments. Error bars show s.e.m. *p = 0.0058, **p = 0.0022, ***p < 0.0001. (b) The synergistic effect of pre-incubation with 100 µg ml−1 AliB-like ORF 1 ligand (SETTFGRDFN) on CSP 2-mediated competence induction was determined by measuring the expression of late competence gene ssbB using a transcriptional fusion of the ssbB promoter region with the luciferase gene, displayed as AUC of the luminescence signal. Results represent three experiments and show s.e.m. For each strain, the expression of ssbB in the presence of ORF 1 ligand is presented as a fold difference compared with the expression value of that strain in the absence of the ORF 1 ligand. *p = 0.0311.

Mentions: To enable functional analyses of the AliB-like ORFs, we made mutants where one or both ORFs were disrupted (see the electronic supplementary material, figure S1 for genetic structures). Since AliB-like ORF 1 bound a peptide fragment that is found in Enterobacteriaceae, which are not part of the normal nasopharyngeal microbiota, we speculated that such binding may elicit a stress response. Streptococcus pneumoniae are naturally competent for genetic transformation and being able to take up DNA in a hostile environment may confer a survival advantage. Transformation rate was therefore compared in the wild-type and mutant strains. Wild-type strain 110.58 had a transformation rate 5.3-fold higher than that of the mutant lacking both ORFs, and 20.2-fold higher than that of the mutant lacking ORF 1 only (figure 3a). The mutant lacking only ORF 2 had a higher transformation rate than the wild-type strain. We confirmed the role of AliB-like ORF 1 in competence by investigating expression of late competence gene ssbB in wild-type strain 110.58 and its ΔORF 1 mutant (figure 3b). We observed no increase in spontaneous competence induction by incubating with AliB-like ORF 1 ligand SETTFGRDFN without adding competence-stimulating peptide (CSP) 2, the peptide released by S. pneumoniae that triggers the cascade leading to competence for genetic transformation (C Hauser 2012, unpublished data). However, pre-incubation with AliB-like ORF 1 ligand increased the competence response to CSP 2 to a significantly greater extent in the wild-type strain 110.58 than in the ΔORF 1 mutant. (The increase in relative ssbB expression in the ΔORF 1 mutant with ORF 1 ligand is equivalent to that observed with a negative control peptide of unrelated sequence, data not shown.)Figure 3.


Streptococcus pneumoniae detects and responds to foreign bacterial peptide fragments in its environment.

Hathaway LJ, Bättig P, Reber S, Rotzetter JU, Aebi S, Hauser C, Heller M, Kadioglu A, Mühlemann K - Open Biol (2014)

Competence gene expression and transformation. (a) Percentage transformation rates of strain 110.58 and its mutants ΔORF 1 + 2, ΔORF 1 and ΔORF 2, showing the mean of three independent experiments. Error bars show s.e.m. *p = 0.0058, **p = 0.0022, ***p < 0.0001. (b) The synergistic effect of pre-incubation with 100 µg ml−1 AliB-like ORF 1 ligand (SETTFGRDFN) on CSP 2-mediated competence induction was determined by measuring the expression of late competence gene ssbB using a transcriptional fusion of the ssbB promoter region with the luciferase gene, displayed as AUC of the luminescence signal. Results represent three experiments and show s.e.m. For each strain, the expression of ssbB in the presence of ORF 1 ligand is presented as a fold difference compared with the expression value of that strain in the absence of the ORF 1 ligand. *p = 0.0311.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4043112&req=5

RSOB130224F3: Competence gene expression and transformation. (a) Percentage transformation rates of strain 110.58 and its mutants ΔORF 1 + 2, ΔORF 1 and ΔORF 2, showing the mean of three independent experiments. Error bars show s.e.m. *p = 0.0058, **p = 0.0022, ***p < 0.0001. (b) The synergistic effect of pre-incubation with 100 µg ml−1 AliB-like ORF 1 ligand (SETTFGRDFN) on CSP 2-mediated competence induction was determined by measuring the expression of late competence gene ssbB using a transcriptional fusion of the ssbB promoter region with the luciferase gene, displayed as AUC of the luminescence signal. Results represent three experiments and show s.e.m. For each strain, the expression of ssbB in the presence of ORF 1 ligand is presented as a fold difference compared with the expression value of that strain in the absence of the ORF 1 ligand. *p = 0.0311.
Mentions: To enable functional analyses of the AliB-like ORFs, we made mutants where one or both ORFs were disrupted (see the electronic supplementary material, figure S1 for genetic structures). Since AliB-like ORF 1 bound a peptide fragment that is found in Enterobacteriaceae, which are not part of the normal nasopharyngeal microbiota, we speculated that such binding may elicit a stress response. Streptococcus pneumoniae are naturally competent for genetic transformation and being able to take up DNA in a hostile environment may confer a survival advantage. Transformation rate was therefore compared in the wild-type and mutant strains. Wild-type strain 110.58 had a transformation rate 5.3-fold higher than that of the mutant lacking both ORFs, and 20.2-fold higher than that of the mutant lacking ORF 1 only (figure 3a). The mutant lacking only ORF 2 had a higher transformation rate than the wild-type strain. We confirmed the role of AliB-like ORF 1 in competence by investigating expression of late competence gene ssbB in wild-type strain 110.58 and its ΔORF 1 mutant (figure 3b). We observed no increase in spontaneous competence induction by incubating with AliB-like ORF 1 ligand SETTFGRDFN without adding competence-stimulating peptide (CSP) 2, the peptide released by S. pneumoniae that triggers the cascade leading to competence for genetic transformation (C Hauser 2012, unpublished data). However, pre-incubation with AliB-like ORF 1 ligand increased the competence response to CSP 2 to a significantly greater extent in the wild-type strain 110.58 than in the ΔORF 1 mutant. (The increase in relative ssbB expression in the ΔORF 1 mutant with ORF 1 ligand is equivalent to that observed with a negative control peptide of unrelated sequence, data not shown.)Figure 3.

Bottom Line: AliB-like ORF 1 binds specifically peptide SETTFGRDFN, matching 50S ribosomal subunit protein L4 of Enterobacteriaceae, and facilitates upregulation of competence for genetic transformation.We found that AliB-like ORF 2 mediates the early phase of nasopharyngeal colonization in vivo.These findings reveal a completely new concept of pneumococcal interspecies communication which may have implications for communication between other bacterial species and for future interventional therapeutics.

View Article: PubMed Central - PubMed

Affiliation: Institute for Infectious Diseases, University of Bern, Bern, Switzerland.

ABSTRACT
Streptococcus pneumoniae is an important cause of bacterial meningitis and pneumonia but usually colonizes the human nasopharynx harmlessly. As this niche is simultaneously populated by other bacterial species, we looked for a role and pathway of communication between pneumococci and other species. This paper shows that two proteins of non-encapsulated S. pneumoniae, AliB-like ORF 1 and ORF 2, bind specifically to peptides matching other species resulting in changes in the pneumococci. AliB-like ORF 1 binds specifically peptide SETTFGRDFN, matching 50S ribosomal subunit protein L4 of Enterobacteriaceae, and facilitates upregulation of competence for genetic transformation. AliB-like ORF 2 binds specifically peptides containing sequence FPPQS, matching proteins of Prevotella species common in healthy human nasopharyngeal microbiota. We found that AliB-like ORF 2 mediates the early phase of nasopharyngeal colonization in vivo. The ability of S. pneumoniae to bind and respond to peptides of other bacterial species occupying the same host niche may play a key role in adaptation to its environment and in interspecies communication. These findings reveal a completely new concept of pneumococcal interspecies communication which may have implications for communication between other bacterial species and for future interventional therapeutics.

Show MeSH
Related in: MedlinePlus