Han Runhua, Xu Letian, Wang Ting, Liu Bin, Wang Lei
TEDA Institute of Biological Sciences and Biotechnology, Nankai UniversityTianjin, China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of EducationTianjin, China.
TEDA Institute of Biological Sciences and Biotechnology, Nankai UniversityTianjin, China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of EducationTianjin, China; Tianjin Key Laboratory of Microbial Functional GenomicsTianjin, China.
Front Microbiol. 2017 Feb 27;8:274. doi: 10.3389/fmicb.2017.00274. eCollection 2017.
Enterohemorrhagic (EHEC) serotype O157:H7 (O157) is one of the most notorious human pathogens, causing severe disease in humans worldwide. O157 specifically colonizes the large intestine of mammals after passing through the small intestine, and this process is influenced by differential signals between the two regions. Small regulatory RNAs (sRNAs) are able to sense and respond to environmental changes and regulate diverse physiological processes in pathogenic bacteria. Although some sRNAs of O157 have been extensively investigated, whether these molecules can sense differences between the small and large intestine and influence the preferential colonization in the large intestine by O157 remains unknown. In this study, we identified a new sRNA, , in O157 which senses the low DNA concentration in the large intestine and contributes to the preferential colonization of the bacteria in this region. The number of O157 wild-type that adhered to the colon is 30.18 times higher than the number that adhered to the ileum of mice, while the number of the Δ mutant that adhered to the colon decreased to 13.27 times higher than the number adhered to the ileum. Furthermore, we found that the expression of is directly activated by the regulator, DeoR, and its expression is positively affected by DNA, which is significantly more abundant in the ileum than in the colon of mice. Additionally, combining the results of informatics predictions and transcriptomic analysis, we found that several virulence genes are up-regulated in the Δ mutant and five candidate genes (, and ) may be its direct targets.
肠出血性大肠杆菌（EHEC）血清型O157:H7（O157）是最臭名昭著的人类病原体之一，在全球范围内导致人类严重疾病。O157在穿过小肠后特异性地定殖于哺乳动物的大肠，这一过程受两个区域间不同信号的影响。小调控RNA（sRNA）能够感知并响应环境变化，调节致病细菌的多种生理过程。尽管O157的一些sRNA已得到广泛研究，但这些分子是否能感知小肠和大肠之间的差异并影响O157在大肠中的优先定殖仍不清楚。在本研究中，我们在O157中鉴定出一种新的sRNA，它能感知大肠中低DNA浓度，并有助于细菌在该区域的优先定殖。定殖于小鼠结肠的O157野生型数量比定殖于回肠的数量高30.18倍，而定殖于结肠的Δ突变体数量降至比定殖于回肠的数量高13.27倍。此外，我们发现该sRNA的表达由调控因子DeoR直接激活，其表达受DNA正向影响，DNA在小鼠回肠中的含量明显高于结肠。另外，结合信息学预测和转录组分析结果，我们发现几个毒力基因在Δ突变体中上调，五个候选基因（、和）可能是其直接靶点。
