Strain-specific impact of PsaR of Streptococcus pneumoniae on global gene expression and virulence.
Previous studies have indicated that PsaR of Streptococcus pneumoniae is a manganese-dependent regulator, negatively affecting the expression of at least seven genes. Here, we extended these observations by transcriptome and proteome analysis of psaR mutants in strains D39 and TIGR4. The microarray analysis identified three shared PsaR targets: the psa operon, pcpA and prtA. In addition, we found 31 genes to be regulated by PsaR in D39 only, most strikingly a cellobiose-specific phosphotransferase system (PTS) and a putative bacteriocin operon (sp0142-sp0146). In TIGR4, 14 PsaR gene targets were detected, with the rlrA pathogenicity islet being the most pronounced. Proteomics confirmed most of the shared gene targets. To examine the contribution of PsaR to pneumococcal virulence, we compared D39 and TIGR4 wild-type (wt) and psaR mutants in three murine infection models. During colonization, no clear effect was observed of the psaR mutation in either D39 or TIGR4. In the pneumonia model, small but significant differences were observed in the lungs of mice infected with either D39wt or DeltapsaR: D39DeltapsaR had an initial advantage in survival in the lungs. Conversely, TIGR4DeltapsaR-infected mice had significantly lower bacterial loads at 24 h only. Finally, during experimental bacteraemia, D39DeltapsaR-infected mice had significantly lower bacterial loads in the bloodstream than wt-infected mice for the first 24 h of infection. TIGR4DeltapsaR showed attenuation at 36 h only. In conclusion, our results show that PsaR of D39 and TIGR4 has a strain-specific role in global gene expression and in the development of bacteraemia in mice.
Department of Pediatrics, Erasmus MC-Sophia Children's Hospital, 3000 DR Rotterdam, The Netherlands.
Wouter T
WT
Hendriksen
Laboratory of Pediatric Infectious Diseases, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands.
Hester J
HJ
Bootsma
Laboratory of Pediatric Infectious Diseases, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands.
Angela
A
van Diepen
Department of Pediatrics, Erasmus MC-Sophia Children's Hospital, 3000 DR Rotterdam, The Netherlands.
Silvia
S
Estevão
Department of Molecular Genetics, University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, PO Box 14, 9750 AA Haren, The Netherlands.
Oscar P
OP
Kuipers
Laboratory of Pediatric Infectious Diseases, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands.
Ronald
R
de Groot
Laboratory of Pediatric Infectious Diseases, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands.
Peter W M
PWM
Hermans
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008168:Lung / Q000382:microbiology; D051379:Mice; D009154:Mutation; D011018:Pneumonia, Pneumococcal / Q000382:microbiology*; D013045:Species Specificity; D013296:Streptococcus pneumoniae / Q000145:classification / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
D001426:Bacterial Proteins; D014157:Transcription Factors