The importance of signal recognition particle for viability of Streptococcus pneumoniae

Abstract number: 1733_919

Pinto E., Andrew P., Faleiro L.

S. pneumoniae is an important Gram-positive bacteria responsible for high levels of human morbidity and mortality, at all ages, around the world, causing pneumonia, meningitis, otitis media and septicaemia.

The dramatic increase in worldwide incidence of antibiotic resistant pneumococcal strains required a better understanding of bacterial physiology to facilitate the development of new antibacterial drugs. The best targets are those essential for cell function. In other Gram-positive and Gram-negative bacteria, deletion of components of the signal recognition particle (SRP) has been shown to cause cell death.

The aim of this research is to confirm that the SRP is essential for pneumococcus viability and its exploitation as a new target for therapy. To achieve this genes ffh and ftsY were amplified by PCR and cloned using the vector pGEM-T Easy. For S. pneumoniae mutagenesis these genes were subcloned into the integrational vector pRKO2 under the control of a tetracycline inducible promoter. S. pneumoniae transformants of strains D39 and TIGR 4 were analysed in order to confirm the plasmid integration and viability dependence of tetracycline. Forward the mariner mutagenesis in vitro was used for transformation of S. pneumoniae D39 to confirm the previous results. A mutant of S. pneumoniae D39Äffh was obtained and no phenotypical differences with the wild type strain were found. The mutation on gene ftsY seems to have a crucial role in S. pneumoniae D39 viability.

This work is supported by the project POCTI/58702/2004.