Genetic screen to define the regulation of beta-hemolysin toxin expression in Streptococcus agalactiae

B组链球菌(GBS)是肠道和阴道菌群的正常组成部分 在15%-30%的健康成年人中。然而，这种细菌可以导致老年人和 免疫功能低下的患者和孕妇，是致命性侵袭的主要原因 新生儿的疾病。GBS通过上皮、内皮和胎盘屏障的转位是 由一种成孔毒素β-溶血素促进，也称为β-溶血性色素脂质 或者是花岗岩。为了确定参与调节β-溶血素表达的因素，我们 用于筛选GBS转座子突变体库的新型无肽培养液的研制 CJB111。试点筛选确定了9个与阳性和阳性相关的新遗传基因座 β-溶血素表达的负性调节。根据初步发现，我们假设 GBS拥有一种调节机制，可以根据β-溶血素的表达 环境。为了揭示这一机制，我们将使用转座子突变文库筛选， RNA-SEQ和代谢组学分析、分离和从头测序 分泌型多肽抑制物。这项探索性工作的结果有可能 导致了一种新型的GBS侵袭状态抑制剂的开发。

Group B Streptococcus (GBS) is a normal constituent of the intestinal and vaginal flora in 15–30% of healthy adults. The bacterium can, however, cause infections in elderly and immunocompromised patients, and pregnant women, and is the main cause of fatal invasive disease in newborns. GBS translocation through epithelial, endothelial, and placental barriers is facilitated by a pore-forming toxin β-hemolysin, also known as the β-hemolytic pigmented lipid or granadaene. To identify factors involved in the regulation of β-hemolysin expression we developed new peptide-free culture media for screening of a transposon mutant library of GBS CJB111. The pilot screens identified nine novel genetic loci associated with positive and negative modulation of β-hemolysin expression. Based on preliminary findings, we hypothesize that GBS possesses a regulatory mechanism that tailors β-hemolysin expression to the environment. To unravel the mechanism, we will employ transposon mutant library screening, RNA-seq and metabolomics analyses, isolation, and de novo sequence determination of secreted peptide-based repressors. The results of this exploratory work have the potential to lead to the development of a novel inhibitor of the invasion state of GBS.