Polyamine synthesis effects capsule expression in Streptococcus pneumoniae TIGR4. Polyamine synthesis effects capsule expression in Streptococcus pneumoniae TIGR4

Purpose: We recently reported that isogenic deletion of lysine decarboxylase (ΔcadA/SP_0916), an enzyme that catalyzes the biosynthesis of polyamine cadaverine in Streptococcus pneumoniae TIGR4 results in loss of capsular polysaccharide (CPS), which constitutes a novel mechanism of regulation of CPS. Here, we conducted RNA-Seq to elucidate molecular mechanisms of CPS regulation in polyamine synthesis impaired pneumococci. Result: Significantly differentially expressed genes in ΔcadA represent pneumococcal pathways involved in the biosynthesis of precursors for CPS and peptidoglycan. Conclusion: We establish a possible link and interchange between two cellular processes such as high energy demanding capsule production and oxidative stress responses in polyamine synthesis impaired pneumococci (ΔcadA). Overall design: Comparing the gene expression changes between S. pneumoniae TIGR4 wild type and polyamine synthesis impaired isogenic deletion strain ΔcadA.

研究目的：我们此前已有报道，在肺炎链球菌（Streptococcus pneumoniae）TIGR4菌株中，赖氨酸脱羧酶（lysine decarboxylase，ΔcadA/SP_0916）可催化多胺尸胺（cadaverine）的生物合成；该酶的同基因缺失株ΔcadA/SP_0916会丧失荚膜多糖（capsular polysaccharide, CPS）合成能力，这揭示了一种全新的CPS调控机制。本研究通过RNA-Seq技术，解析多胺合成缺陷型肺炎链球菌中CPS调控的分子机制。
研究结果：ΔcadA菌株中显著差异表达的基因，参与了肺炎链球菌荚膜多糖与肽聚糖前体的生物合成通路。
研究结论：本研究证实，在多胺合成缺陷型肺炎链球菌（ΔcadA）中，高能量需求的荚膜合成与氧化应激应答这两类细胞过程之间可能存在关联与相互调控。
整体实验设计：比较肺炎链球菌TIGR4野生型菌株与多胺合成缺陷型同基因缺失株ΔcadA的基因表达变化。