Effect of decreased BCAA synthesis through disruption of ilvC gene on the virulence of Streptococcus pneumoniae

다국어 초록 (Multilingual Abstract)

Streptococcus pneumoniae (pneumococcus) isresponsible for significant morbidity and mortality worldwide.
It causes a variety of life-threatening infections suchas pneumonia, bacteremia, and meningitis. In bacterialphysiology, the metabolic pathway of branched-chainamino acids (BCAAs) plays an important role in virulence.
Nonetheless, the function of IlvC, one of the enzymesinvolved in the biosynthesis of BCAAs, in S. pneumoniaeremains unclear. Here, we demonstrated that downregulationof BCAA biosynthesis by ilvC ablation can diminishBCAA concentration and expression of pneumolysin (Ply)and LytA, and subsequently attenuate virulence. Infectionwith an ilvC mutant showed significantly reduced mortalityand colonization in comparison with strain D39 (serotype2, wild type), suggesting that ilvC can potentiate S. pneumoniaevirulence due to adequate BCAA synthesis. Takentogether, these results suggest that the function of ilvC inBCAA synthesis is essential for virulence factor and couldplay an important role in the pathogenesis of respiratoryinfections.

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