title: New adhesin functions of surface-exposed pneumococcal proteins.
abstract: BACKGROUND
  Streptococcus pneumoniae is a widely distributed commensal Gram-positive bacteria of the upper respiratory tract. Pneumococcal colonization can progress to invasive disease, and thus become lethal, reason why antibiotics and vaccines are designed to limit the dramatic effects of the bacteria in such cases. As a consequence, pneumococcus has developed efficient antibiotic resistance, and the use of vaccines covering a limited number of serotypes such as Pneumovax and Prevnar results in the expansion of non-covered serotypes. Pneumococcal surface proteins represent challenging candidates for the development of new therapeutic targets against the bacteria. Despite the number of described virulence factors, we believe that the majority of them remain to be characterized. This is the reason why pneumococcus invasion processes are still largely unknown.
  
  
  RESULTS
  Availability of genome sequences facilitated the identification of pneumococcal surface proteins bearing characteristic motifs such as choline-binding proteins (Cbp) and peptidoglycan binding (LPXTG) proteins. We designed a medium throughput approach to systematically test for interactions between these pneumococcal surface proteins and host proteins (extracellular matrix proteins, circulating proteins or immunity related proteins). We cloned, expressed and purified 28 pneumococcal surface proteins. Interactions were tested in a solid phase assay, which led to the identification of 23 protein-protein interactions among which 20 are new.
  
  
  CONCLUSIONS
  We conclude that whether peptidoglycan binding proteins do not appear to be major adhesins, most of the choline-binding proteins interact with host proteins (elastin and C reactive proteins are the major Cbp partners). These newly identified interactions open the way to a better understanding of host-pneumococcal interactions.
authors.affiliation: Institut de Biologie Structurale, UMR, Université Joseph Fourier, CNRS, CEA, Grenoble, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Frolet
authors.forename: Meryam
authors.initials: M
authors.lastname: Beniazza
authors.forename: Laure
authors.initials: L
authors.lastname: Roux
authors.forename: Benoit
authors.initials: B
authors.lastname: Gallet
authors.forename: Marjolaine
authors.initials: M
authors.lastname: Noirclerc-Savoye
authors.forename: Thierry
authors.initials: T
authors.lastname: Vernet
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Di Guilmi
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011008:Pneumococcal Infections / Q000378:metabolism* / Q000382:microbiology; D011485:Protein Binding; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000378:metabolism*
chemical_list: D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; D008565:Membrane Proteins