Listeria monocytogenes 10403S Arginine Repressor ArgR Finely Tunes Arginine Metabolism Regulation under Acidic Conditions.
Listeria monocytogenes 10403S Arginine Repressor ArgR Finely Tunes Arginine Metabolism Regulation under Acidic Conditions.
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单核细胞增生李斯特氏菌 10403S 精氨酸阻遏蛋白 ArgR 精细调节酸性条件下的精氨酸代谢调节
DOI：
10.3389/fmicb.2017.00145
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发表时间：
2017
影响因子：
5.2
通讯作者：
Song H
中科院分区：
文献类型：
--
作者：
Cheng C;Dong Z;Han X;Sun J;Wang H;Jiang L;Yang Y;Ma T;Chen Z;Yu J;Fang W;Song H
单核细胞增多性李斯特菌能够定植于人类和动物肠道，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氏菌必须在胃的低 pH 环境中生存。单核细胞增生李斯特菌编码功能性 ArgR，这是一种属于 ArgR/AhrC 精氨酸阻遏蛋白家族的转录调节因子。我们的目的是阐明ArgR在精氨酸代谢调节中的具体功能，更重要的是在单增李斯特菌的耐酸性中的具体功能。我们发现，在 10 mM 精氨酸存在的情况下，ArgR 会抑制 argGH 和 argCJBDF 操纵子的转录和表达，表明单增李斯特菌 ArgR 在精氨酸生物合成途径的反馈抑制中发挥 ArgR/AhrC 家族蛋白的经典作用。值得注意的是，当细菌在缺乏精氨酸的情况下暴露于 pH 5.5 时，argA（编码精氨酸脱亚胺酶）和 sigB（编码另一种 sigma 因子 B）的转录和表达也受到 ArgR 的显着抑制。然而，添加精氨酸使 ArgR 能够去抑制这两个基因的转录和表达。电泳迁移率变动分析表明，ArgR 与 argC、argG、arcA 和 sigB 启动子区域中推定的 ARG 盒结合。在 argG 启动子控制下使用 gfp 进行报告基因分析表明，ArgR 能够激活 argG 启动子。出乎意料的是，在用乳酸调节至 pH 3.5 的 BHI 培养基中，argR 的缺失显着增加了细菌的存活率。我们得出结论，这种现象是由于 arcA 和 sigB 的激活所致。总的来说，我们的结果表明，在乳酸诱导的酸应激期间，单增李斯特菌 ArgR 通过精氨酸生物合成操纵子和分解代谢 arcA 基因的负转录调节，以不依赖于精氨酸的方式精细调节精氨酸代谢。 ArgR 似乎还通过精氨酸依赖性方式的抗抑制来激活分解代谢和 sigB 转录。
Listeria monocytogenes is able to colonize human and animal intestinal tracts and to subsequently cross the intestinal barrier, causing systemic infection. For successful establishment of infection, L. monocytogenes must survive the low pH environment of the stomach. L. monocytogenes encodes a functional ArgR, a transcriptional regulator belonging to the ArgR/AhrC arginine repressor family. We aimed at clarifying the specific functions of ArgR in arginine metabolism regulation, and more importantly, in acid tolerance of L. monocytogenes. We showed that ArgR in the presence of 10 mM arginine represses transcription and expression of the argGH and argCJBDF operons, indicating that L. monocytogenes ArgR plays the classical role of ArgR/AhrC family proteins in feedback inhibition of the arginine biosynthetic pathway. Notably, transcription and expression of arcA (encoding arginine deiminase) and sigB (encoding an alternative sigma factor B) were also markedly repressed by ArgR when bacteria were exposed to pH 5.5 in the absence of arginine. However, addition of arginine enabled ArgR to derepress the transcription and expression of these two genes. Electrophoretic mobility shift assays showed that ArgR binds to the putative ARG boxes in the promoter regions of argC, argG, arcA, and sigB. Reporter gene analysis with gfp under control of the argG promoter demonstrated that ArgR was able to activate the argG promoter. Unexpectedly, deletion of argR significantly increased bacterial survival in BHI medium adjusted to pH 3.5 with lactic acid. We conclude that this phenomenon is due to activation of arcA and sigB. Collectively, our results show that L. monocytogenes ArgR finely tunes arginine metabolism through negative transcriptional regulation of the arginine biosynthetic operons and of the catabolic arcA gene in an arginine-independent manner during lactic acid-induced acid stress. ArgR also appears to activate catabolism as well as sigB transcription by anti-repression in an arginine-dependent way.