The nitric oxide reductase of enterohaemorrhagic Escherichia coli plays an important role for the survival within macrophages
The nitric oxide reductase of enterohaemorrhagic Escherichia coli plays an important role for the survival within macrophages
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DOI：
10.1111/j.1365-2958.2012.08122.x
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发表时间：
2012-08
影响因子：
3.6
通讯作者：
Takeshi Shimizu;Hiroyasu Tsutsuki;Akio Matsumoto;H. Nakaya;M. Noda
中科院分区：
文献类型：
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作者：
Takeshi Shimizu;Hiroyasu Tsutsuki;Akio Matsumoto;H. Nakaya;M. Noda
在肠出血性大肠杆菌（EHEC）O 157中，存在两种类型的厌氧一氧化氮（NO）还原酶基因，一个完整的基因（norV）和一个204 bp缺失的基因（norVs）。流行病学分析显示，norV型EHEC比norV型EHEC毒力更强。因此，为了揭示NO还原酶在EHEC感染过程中的作用，我们构建了同基因norV-型和norVs-型EHEC突变株。在厌氧条件下，norV-型EHEC可以免受NO介导的生长抑制，而norVs-型EHEC突变株则不能，表明EHEC的NorV具有厌氧解毒作用。然后我们研究了巨噬细胞内NO还原酶的作用。与norVs-型EHEC相比，norV-型EHEC在巨噬细胞内产生较低的NO水平。此外，与norVs-型EHEC相比，norV-型EHEC导致巨噬细胞内更高水平的滋贺毒素2（Stx 2）。最后，norV型EHEC的存活率高于norVs型EHEC。这些数据表明，完整的norV基因对EHEC在巨噬细胞内的生存起着重要作用，并且是EHEC的直接毒力决定因素。
In enterohaemorrhagic Escherichia coli (EHEC) O157, there are two types of anaerobic nitric oxide (NO) reductase genes, an intact gene (norV) and a 204 bp deletion gene (norVs). Epidemiological analysis has revealed that norV‐type EHEC are more virulent than norVs‐type EHEC. Thus, to reveal the role of NO reductase during EHEC infection, we constructed isogenic norV‐type and norVs‐type EHEC mutant strains. Under anaerobic conditions, the norV‐type EHEC was protected from NO‐mediated growth inhibition, while the norVs‐type EHEC mutant strain was not, suggesting that NorV of EHEC was effective in the anaerobic detoxification. We then investigated the role of NO reductase within macrophages. The norV‐type EHEC produced a lower NO level within macrophages compared with the norVs‐type EHEC. Moreover, the norV‐type EHEC resulted in higher levels of Shiga toxin 2 (Stx2) within macrophages compared with the norVs‐type EHEC. Finally, the norV‐type EHEC showed a better level of survival than the norVs‐type EHEC. These data suggest that the intact norV gene plays an important role for the survival of EHEC within macrophages, and is a direct virulence determinant of EHEC.