title: Cytosporone B, an inhibitor of the type III secretion system of Salmonella enterica serovar Typhimurium.
abstract: Bacterial virulence factors have been increasingly regarded as attractive targets for development of novel antibacterial agents. Virulence inhibitors are less likely to generate bacterial resistance, which makes them superior to traditional antibiotics that target bacterial viability. Salmonella enterica serovar Typhimurium, an important food-borne human pathogen, has type III secretion system (T3SS) as its major virulence factor. T3SS secretes effector proteins to facilitate invasion into host cells. In this study, we identified several analogs of cytosporone B (Csn-B) that strongly block the secretion of Salmonella pathogenicity island 1 (SPI-1)-associated effector proteins, without affecting the secretion of flagellar protein FliC in vitro. Csn-B and two other derivatives exhibited a strong inhibitory effect on SPI-1-mediated invasion to HeLa cells, while no significant toxicity to bacteria was observed. Nucleoid proteins Hha and H-NS bind to the promoters of SPI-1 regulator genes hilD, hilC, and rtsA to repress their expression and consequently regulate the expression of SPI-1 apparatus and effector genes. We found that Csn-B upregulated the transcription of hha and hns, implying that Csn-B probably affected the secretion of effectors through the Hha-H-NS regulatory pathway. In summary, this study presented an effective SPI-1 inhibitor, Csn-B, which may have potential in drug development against antibiotic-resistant Salmonella.
authors: Key Laboratory of Chemical Biology Ministry of Education, School of Pharmaceutical Sciences, Shandong University, Jinan, China.
authors: Jianfang
authors: J
authors: Li
authors: Chao
authors: C
authors: Lv
authors: Weiyang
authors: W
authors: Sun
authors: Zhenyu
authors: Z
authors: Li
authors: Xiaowei
authors: X
authors: Han
authors: Yaoyao
authors: Y
authors: Li
authors: Yuemao
authors: Y
authors: Shen
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D044404:Genomic Islands; D006367:HeLa Cells; D006801:Humans; D010648:Phenylacetates / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C119659:HilC protein, Salmonella typhimurium; C119660:HilD protein, Salmonella typhimurium; D010648:Phenylacetates; C419942:Spi1 protein, Salmonella; D014157:Transcription Factors; D037521:Virulence Factors; C531461:cytosporone B