Thioredoxin A Is Essential for Motility and Contributes to Host Infection of Listeria monocytogenes via Redox Interactions.
Thioredoxin A Is Essential for Motility and Contributes to Host Infection of Listeria monocytogenes via Redox Interactions.
复制标题
硫氧还蛋白 A 对于运动至关重要，并通过氧化还原相互作用促进单核细胞增生李斯特菌的宿主感染。
DOI：
10.3389/fcimb.2017.00287
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发表时间：
2017
影响因子：
5.7
通讯作者：
Song H
中科院分区：
文献类型：
--
作者：
Cheng C;Dong Z;Han X;Wang H;Jiang L;Sun J;Yang Y;Ma T;Shao C;Wang X;Chen Z;Fang W;Freitag NE;Huang H;Song H
微生物利用硫氧还蛋白系统来防御氧化应激并确保正确的二硫键以维持蛋白质功能。单核细胞增生李斯特菌已被证明编码一种假定的硫氧还蛋白 TrxA，但其生物学作用和潜在机制仍不清楚。在这里，我们发现，在用硫醇特异性氧化剂二酰胺处理的细菌中，单增李斯特菌 TrxA 的表达被显着诱导。 trxA 的缺失显着损害了病原体对二酰胺的耐受性，并且主要损害了人肠上皮 Caco-2 细胞的早期感染阶段。此外，大多数trxA突变细菌与聚合肌动蛋白无关，而与聚合肌动蛋白相关的罕见细菌在感染过程中表现出非常短的尾巴或云团。由SigH调控的TrxA的缺失或组成型过度表达，严重削弱了病原体的毒力。单增李斯特菌的转录组分析显示，与野生型相比，ΔtrxA 突变体中有超过 270 个基因的转录存在差异，特别是毒力相关基因 plcA、mpl、hly、actA 和 plcB。特别是，TrxA的缺失完全降低了LLO的表达，从而导致溶血活性彻底受损。这些毒力因子的表达受到主调节器 PrfA 的正向调节，这里发现主调节器 PrfA 使用 TrxA 来维持其还原形式以进行激活。有趣的是，trxA 缺失突变体完全缺乏鞭毛并且不能运动。我们进一步证实，这种缺陷可归因于 TrxA 维持 MogR（鞭毛形成的关键调节因子）细胞内单体状态的降低，以确保正确的二聚化。总之，我们首次证明单增李斯特菌硫氧还蛋白 A 作为一种重要的细胞还原酶对于维持细菌胞质中的高度还原环境至关重要，这为蛋白质折叠和激活提供了有利条件，因此有助于细菌毒力和运动性。
Microbes employ the thioredoxin system to defend against oxidative stress and ensure correct disulfide bonding to maintain protein function. Listeria monocytogenes has been shown to encode a putative thioredoxin, TrxA, but its biological roles and underlying mechanisms remain unknown. Here, we showed that expression of L. monocytogenes TrxA is significantly induced in bacteria treated with the thiol-specific oxidizing agent, diamide. Deletion of trxA markedly compromised tolerance of the pathogen to diamide, and mainly impaired early stages of infection in human intestinal epithelial Caco-2 cells. In addition, most trxA mutant bacteria were not associated with polymerized actin, and the rare bacteria that were associated with polymerized actin displayed very short tails or clouds during infection. Deletion or constitutive overexpression of TrxA, which was regulated by SigH, severely attenuated the virulence of the pathogen. Transcriptome analysis of L. monocytogenes revealed over 270 genes that were differentially transcribed in the ΔtrxA mutant compared to the wild-type, especially for the virulence-associated genes plcA, mpl, hly, actA, and plcB. Particularly, deletion of TrxA completely reduced LLO expression, and thereby led to a thoroughly impaired hemolytic activity. Expression of these virulence factors are positively regulated by the master regulator PrfA that was found here to use TrxA to maintain its reduced forms for activation. Interestingly, the trxA deletion mutant completely lacked flagella and was non-motile. We further confirmed that this deficiency is attributable to TrxA in maintaining the reduced intracellular monomer status of MogR, the key regulator for flagellar formation, to ensure correct dimerization. In summary, we demonstrated for the first time that L. monocytogenes thioredoxin A as a vital cellular reductase is essential for maintaining a highly reducing environment in the bacterial cytosol, which provides a favorable condition for protein folding and activation, and therefore contributes to bacterial virulence and motility.