Pollard Dominic J, Young Joanna C, Covarelli Valentina, Herrera-León Silvia, Connor Thomas R, Fookes Maria, Walker Danielle, Echeita Aurora, Thomson Nicholas R, Berger Cedric N, Frankel Gad
MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, United Kingdom.
Sección de Enterobacterias, Servicio de Bacteriología, Centro Nacional de Microbiología, ISCIII, Majadahonda, Spain.
Infect Immun. 2016 Nov 18;84(12):3618-3628. doi: 10.1128/IAI.00704-16. Print 2016 Dec.
Salmonella species utilize type III secretion systems (T3SSs) to translocate effectors into the cytosol of mammalian host cells, subverting cell signaling and facilitating the onset of gastroenteritis. In this study, we compared a draft genome assembly of Salmonella enterica subsp. salamae strain 3588/07 against the genomes of S. enterica subsp. enterica serovar Typhimurium strain LT2 and Salmonella bongori strain 12419. S. enterica subsp. salamae encodes the Salmonella pathogenicity island 1 (SPI-1), SPI-2, and the locus of enterocyte effacement (LEE) T3SSs. Though several key S Typhimurium effector genes are missing (e.g., avrA, sopB, and sseL), S. enterica subsp. salamae invades HeLa cells and contains homologues of S. bongori sboK and sboC, which we named seoC SboC and SeoC are homologues of EspJ from enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC, respectively), which inhibit Src kinase-dependent phagocytosis by ADP-ribosylation. By screening 73 clinical and environmental Salmonella isolates, we identified EspJ homologues in S. bongori, S. enterica subsp. salamae, and Salmonella enterica subsp. arizonae The β-lactamase TEM-1 reporter system showed that SeoC is translocated by the SPI-1 T3SS. All the Salmonella SeoC/SboC homologues ADP-ribosylate Src E310 in vitro Ectopic expression of SeoC/SboC inhibited phagocytosis of IgG-opsonized beads into Cos-7 cells stably expressing green fluorescent protein (GFP)-FcγRIIa. Concurrently, S. enterica subsp. salamae infection of J774.A1 macrophages inhibited phagocytosis of beads, in a seoC-dependent manner. These results show that S. bongori, S. enterica subsp. salamae, and S. enterica subsp. arizonae share features of the infection strategy of extracellular pathogens EPEC and EHEC and shed light on the complexities of the T3SS effector repertoires of Enterobacteriaceae.
沙门氏菌利用III型分泌系统（T3SSs）将效应蛋白转运到哺乳动物宿主细胞的胞质溶胶中，破坏细胞信号传导并促进肠胃炎的发生。在本研究中，我们将肠炎沙门氏菌亚种萨拉姆菌株3588/07的基因组草图组装与肠炎沙门氏菌亚种肠道鼠伤寒血清型菌株LT2和邦戈尔沙门氏菌菌株12419的基因组进行了比较。肠炎沙门氏菌亚种萨拉姆编码沙门氏菌致病岛1（SPI-1）、SPI-2和肠细胞脱落位点（LEE）T3SSs。尽管几个关键的鼠伤寒沙门氏菌效应基因缺失（例如，avrA、sopB和sseL），但肠炎沙门氏菌亚种萨拉姆仍能侵入HeLa细胞，并含有邦戈尔沙门氏菌sboK和sboC的同源物，我们将其命名为seoC。SboC和SeoC是来自肠致病性大肠杆菌和肠出血性大肠杆菌（分别为EPEC和EHEC）的EspJ的同源物，它们通过ADP-核糖基化抑制Src激酶依赖性吞噬作用。通过筛选73株临床和环境沙门氏菌分离株，我们在邦戈尔沙门氏菌、肠炎沙门氏菌亚种萨拉姆和肠炎沙门氏菌亚种亚利桑那菌中鉴定出了EspJ同源物。β-内酰胺酶TEM-1报告系统显示SeoC通过SPI-1 T3SS转运。所有沙门氏菌的SeoC/SboC同源物在体外均能对Src E310进行ADP-核糖基化。SeoC/SboC的异位表达抑制了IgG调理珠对稳定表达绿色荧光蛋白（GFP）-FcγRIIa的Cos-7细胞的吞噬作用。同时，肠炎沙门氏菌亚种萨拉姆对J774.A1巨噬细胞的感染以依赖seoC的方式抑制了珠子的吞噬作用。这些结果表明，邦戈尔沙门氏菌、肠炎沙门氏菌亚种萨拉姆和肠炎沙门氏菌亚种亚利桑那菌具有细胞外病原体EPEC和EHEC感染策略的特征，并揭示了肠杆菌科T3SS效应蛋白库的复杂性。
