The Listeria monocytogenes σB regulon and its virulence-associated functions are inhibited by a small molecule.
The Listeria monocytogenes σB regulon and its virulence-associated functions are inhibited by a small molecule.
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作者：
Palmer ME;Chaturongakul S;Wiedmann M;Boor KJ
应激响应性替代σ因子σB在不同的革兰氏阳性细菌属中是保守的。在单核细胞增生李斯特菌中，σB调节>150个基因的转录，包括在宿主相关应激条件下（例如在人胃肠道中遇到的那些）促成毒力和细菌存活的基因。通过使用基于细胞的高通量测定筛选约57，000种天然和合成的小分子，鉴定了单核细胞增生李斯特菌σB活性的抑制剂。化合物氟代苯基苯乙烯磺酰胺（FPSS）（IC 50 = 3.5 µM）下调了先前鉴定为单核细胞增生李斯特菌10403 S中σB调节子成员的大多数基因，从而产生了与10403 S ΔsigB菌株相当的转录谱。具体而言，在FPSS下调的208个基因中，75%先前已被鉴定为受σB正调控。下调的基因包括关键毒力和胁迫反应基因，如inlA、inlB、bsh、hfq、opuC和bilE。从功能上看，FPSS还能抑制单核细胞增生李斯特菌对人肠上皮细胞的侵袭和胆盐水解酶的活性。FPSS抑制单核细胞增多性李斯特菌和枯草芽孢杆菌中的σB活性的能力表明其在多种革兰氏阳性菌属中作为σB的特异性抑制剂的效用。σB转录因子调节负责细菌在变化的环境条件下存活和毒力的基因的表达;因此，这种替代性σ因子对于单核细胞增生李斯特菌和其他革兰氏阳性细菌的传播是重要的。对σB活性的调节是复杂且严格控制的，反映了该因子在细菌代谢中的关键作用。我们提出了多条证据，表明氟苯基苯乙烯磺酰胺（FPSS）特异性抑制革兰氏阳性细菌属中σB的活性，即，单核细胞增多性李斯特菌和枯草芽孢杆菌中。因此，FPSS是一个重要的新工具，将使新的方法，探索复杂的调控网络，单核细胞增生李斯特菌和其他革兰氏阳性病原体和研究小分子应用控制病原体的传播。
The stress-responsive alternative sigma factor σB is conserved across diverse Gram-positive bacterial genera. In Listeria monocytogenes, σB regulates transcription of >150 genes, including genes contributing to virulence and to bacterial survival under host-associated stress conditions, such as those encountered in the human gastrointestinal lumen. An inhibitor of L. monocytogenes σB activity was identified by screening ~57,000 natural and synthesized small molecules using a high-throughput cell-based assay. The compound fluoro-phenyl-styrene-sulfonamide (FPSS) (IC50 = 3.5 µM) downregulated the majority of genes previously identified as members of the σB regulon in L. monocytogenes 10403S, thus generating a transcriptional profile comparable to that of a 10403S ΔsigB strain. Specifically, of the 208 genes downregulated by FPSS, 75% had been identified previously as positively regulated by σB. Downregulated genes included key virulence and stress response genes, such as inlA, inlB, bsh, hfq, opuC, and bilE. From a functional perspective, FPSS also inhibited L. monocytogenes invasion of human intestinal epithelial cells and bile salt hydrolase activity. The ability of FPSS to inhibit σB activity in both L. monocytogenes and Bacillus subtilis indicates its utility as a specific inhibitor of σB across multiple Gram-positive genera. The σB transcription factor regulates expression of genes responsible for bacterial survival under changing environmental conditions and for virulence; therefore, this alternative sigma factor is important for transmission of L. monocytogenes and other Gram-positive bacteria. Regulation of σB activity is complex and tightly controlled, reflecting the key role of this factor in bacterial metabolism. We present multiple lines of evidence indicating that fluoro-phenyl-styrene-sulfonamide (FPSS) specifically inhibits activity of σB across Gram-positive bacterial genera, i.e., in both Listeria monocytogenes and Bacillus subtilis. Therefore, FPSS is an important new tool that will enable novel approaches for exploring complex regulatory networks in L. monocytogenes and other Gram-positive pathogens and for investigating small-molecule applications for controlling pathogen transmission.