Zhejiang University Institute of Preventive Veterinary Medicine and Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, 388 Yuhangtang Road, Hangzhou, Zhejiang 310058, PR China.
Zhejiang Aquatic Disease Prevention and Quarantine Center, 20 Yile Road, Hangzhou, Zhejiang 310012, PR China.
J Med Microbiol. 2013 Jun;62(Pt 6):813-821. doi: 10.1099/jmm.0.055145-0. Epub 2013 Mar 21.
The foodborne pathogen Listeria monocytogenes is able to colonize the human and animal intestinal tracts and subsequently crosses the intestinal barrier, causing systemic infection. For successful establishment of infection, L. monocytogenes must survive and adapt to the low pH environment of the stomach. Gene sequence analysis indicates that lmo0043, an orthologue of arcA, encodes a protein containing conserved motifs and critical active amino acids characteristic of arginine deiminase that mediates an arginine deimination reaction. We attempted to characterize the role of ArcA in acid tolerance in vitro and in mice models. Transcription of arcA was significantly increased in L. monocytogenes culture subjected to acid stress at pH 4.8, as compared with that at pH 7.0. Deletion of arcA impaired growth of L. monocytogenes under mild acidic conditions at pH 5.5, and reduced its survival in synthetic human gastric fluid at pH 2.5 and in the murine stomach. Bacterial load in the spleen of mice intraperitoneally inoculated with an arcA deletion mutant was significantly lower than that of the wild-type strain. These phenotypic changes were recoverable by genetic complementation. Thus, we conclude that L. monocytogenes arcA not only mediates acid tolerance in vitro but also participates in gastric survival and virulence in mice.
食源性病原体单核细胞增生李斯特菌能够定殖于人类和动物的肠道，并随后穿过肠道屏障，引起全身感染。为了成功建立感染，单核细胞增生李斯特菌必须在胃的低 pH 环境中存活和适应。基因序列分析表明，lmo0043，arcA 的直系同源物，编码一种含有保守基序和关键活性氨基酸的蛋白质，这些氨基酸特征是精氨酸脱亚氨酶介导的精氨酸脱亚氨反应。我们试图描述 ArcA 在体外和小鼠模型中的耐酸作用。与 pH7.0 相比，arcA 在 pH4.8 的酸应激培养物中的转录明显增加。ArcA 的缺失削弱了单核细胞增生李斯特菌在 pH5.5 的温和酸性条件下的生长，并降低了其在 pH2.5 的合成人胃液和小鼠胃中的存活率。用 arcA 缺失突变体腹腔内接种的小鼠脾脏中的细菌负荷明显低于野生型菌株。这些表型变化可以通过遗传互补来恢复。因此，我们得出结论，单核细胞增生李斯特菌 arcA 不仅介导体外耐酸作用，而且参与小鼠胃内的存活和毒力。
