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FRIBIO-Biologi og biomedisin

Competence-induced cell lysis in Streptococcus pneumoniae: Implications for horizontal gene transfer and virulence

Awarded: NOK 2.4 mill.

Streptococcus pneumoniae have the ability to enter a transient phenotype termed competence for natural transformation, which enables the bacterial cells to take up free DNA from the surrounding environment. Recently, it was discovered that competent cells also aquire the ability to lyse neighbouring bacteria. The key players in this lysis mechanism is CbpD and ComM. CbpD is a putative murein hydrolase produced specifically by the competent cells, and is currently thought to be the principal component unde rlying cell lysis. ComM is a competence induced immunity protein that shields the competent bacteria from the action of CbpD. Horizontal gene transfer by natural transformation has a large impact on the susceptibility of S. pneumoniae towards antibiotics. The lysis mechanism described above is currently thought to have high impact on the efficiancy of horizontal gene into S. pneumoniae, since it ensures the release of free DNA from neighbouring bacteria concomitant with competence development. Hence, det ailed knowledge concerning CbpD, ComM, and their function in competence-induced cell lysis is crucial to develop efficient countermeasures to combat future proliferation of antibiotic resistant S. pneumoniae. Previous studies have indicated that competenc e development might be an intrinsic part of the S. pneumoniae infection.This could represent a potential "achilles heel" of the bacterium, since the competent bacteria rely on the ComM protein to avoid being lysed by their own toxin (CbpD). Using biophoto nic imaging, we will analyse in detail the timing of competence development in a mouse model. Based on these results, the same tecnique will be used to investigate whether bacteria containing a deleted comM gene become attenuated following competence deve lopment. If so, future research can be directed at finding ways to block the ComM immunity pathway.

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FRIBIO-Biologi og biomedisin

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