σB contributes to Listeria monocytogenes invasion by controlling expression of inlA and inlB
σB contributes to Listeria monocytogenes invasion by controlling expression of inlA and inlB
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DOI：
10.1099/mic.0.28070-0
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发表时间：
2005-10-01
期刊：
影响因子：
2.8
通讯作者：
Boor, KJ
中科院分区：
文献类型：
--
作者：
Kim, H;Marquis, H;Boor, KJ
单核细胞增多性李斯特菌侵入非吞噬细胞的能力对于系统性李斯特菌感染的发展是重要的。作者先前报道，一个L。单核细胞增生性δ sigB菌株在侵入人肠上皮细胞方面有缺陷，部分原因是主要侵入基因inIA的表达降低。为了表征在sigma（B）控制下的另外的侵入机制，产生携带inIA、inl B和sigB中的框内缺失的组合的突变体。对细菌侵入人肠上皮细胞Caco-2和肝细胞HepG-2细胞系的定量评估表明，sigma（B）有助于InIA和InIB介导的L.单核细胞增多症。先前对主要毒力基因调节因子正调控因子A（PrfA）上游的sigma（B）依赖性P2（prfA）启动子的鉴定表明，sigma B对各种毒力基因（包括inIA）表达的贡献至少部分通过PrfA介导。为了检验这一假设，比较了Delta sigB和Delta prfA菌株的相对侵入能力。Delta sigB和Delta prfA菌株的指数期细胞在侵袭时同样有缺陷;然而，稳定期Delta sigB细胞的侵袭性显著低于稳定期Delta prfA细胞，这表明B对侵袭的贡献超出了稳定期L中通过PrfA介导的贡献。单核细胞增多症TaqMan定量逆转录酶PCR进一步证明，在稳定期L中，in/A和inl B的表达以sigma（B）依赖的方式显著增加。单核细胞增多症。总之，这项研究的结果提供了强有力的生物学证据，表明西格玛（B）在L。单核细胞增多症侵入非吞噬细胞，主要通过控制inIA和inIB表达介导。
The ability of Listeria monocytogenes to invade non-phagocytic cells is important for development of a systemic listeriosis infection. The authors previously reported that a L. monocytogenes Delta sigB strain is defective in invasion into human intestinal epithelial cells, in part, due to decreased expression of a major invasion gene, inIA. To characterize additional invasion mechanisms under the control of sigma(B), mutants were generated carrying combinations of in-frame deletions in inIA, inlB and sigB. Quantitative assessment of bacterial invasion into the human enterocyte Caco-2 and hepatocyte HepG-2 cell lines demonstrated that sigma(B) contributes to both InIA and InIB-mediated invasion of L. monocytogenes. Previous identification of the sigma(B)-dependent P2(prfA) promoter upstream of the major virulence gene regulator, positive regulatory factor A (PrfA), suggested that the contributions of sigma B to expression of various virulence genes, including inIA, could be at least partially mediated through PrfA. To test this hypothesis, relative invasion capabilities of Delta sigB and Delta prfA strains were compared. Exponential-phase cells of the Delta sigB and Delta prfA strains were similarly defective at invasion; however, stationary-phase Delta sigB cells were significantly less invasive than stationary-phase Delta prfA cells, suggesting that the contributions of a B to invasion extend beyond those mediated through PrfA in stationary-phase L. monocytogenes. TaqMan quantitative reverse-transcriptase PCRs further demonstrated that expression of in/A and inlB was greatly increased in a sigma(B)-dependent manner in stationary-phase L. monocytogenes. Together, results from this study provide strong biological evidence of a critical role for sigma(B) in L. monocytogenes invasion into non-phagocytic cells, primarily mediated through control of inIA and inlB expression.