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Multifunctional role of choline binding protein G in pneumococcal pathogenesis
B Mann1, C Orihuela, J Antikainen
1St. Jude Children's Research Hospital, 332 N. Lauderdale Rd., Memphis, TN 38105, USA.
Infection and Immunity
|January 24, 2006
Summary
Choline binding protein G (CbpG) from Streptococcus pneumoniae acts as a protease, cleaving host proteins and aiding bacterial adherence. Variations in CbpG affect its function and virulence, impacting disease severity.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Choline binding proteins (Cbp) family members are surface proteins of Streptococcus pneumoniae.
- CbpG's role in adherence and virulence has been proposed but remained unclear.
- Sequence analysis suggests CbpG is a serine protease.
Purpose of the Study:
- To elucidate the function of CbpG in Streptococcus pneumoniae.
- To investigate the role of CbpG's choline binding domain in its activity and virulence.
- To explore the potential of CbpG as a vaccine target.
Main Methods:
- Sequence analysis of cbpG alleles.
- Proteolytic activity assays using fibronectin and casein.
- Adherence assays with eukaryotic cells using recombinant CbpG.
- In vitro and in vivo virulence studies in mouse models.
- Immunization studies in mice.
Main Results:
- CbpG exhibits proteolytic activity against fibronectin and casein.
- Full-length and truncated CbpG proteins demonstrate adherence to eukaryotic cells.
- Mutants lacking CbpG or expressing truncated CbpG showed reduced adherence and virulence in mice.
- Immunization with recombinant CbpG conferred protection against colonization and sepsis.
Conclusions:
- CbpG is a multifunctional serine protease involved in cleaving host extracellular matrix and bacterial adherence.
- Distinct functions of CbpG depend on the presence or absence of its choline binding domain.
- CbpG represents a potential target for therapeutic and prophylactic strategies against pneumococcal infections.
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