He Jiaojiao, Liu Su, Fang Qingjian, Gu Hanjie, Hu Yonghua
School of Life Sciences, Hainan University, Haikou 570228, China.
Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
Microorganisms. 2023 Mar 24;11(4):827. doi: 10.3390/microorganisms11040827.
is an important fish pathogen that causes substantial economic losses. In order to understand its pathogenic mechanism, additional new virulence factors need to be identified. The bacterial thioredoxin system is a major disulfide reductase system, but its function is largely unknown in . In this study, we investigated the roles of the thioredoxin system in (named TrxB, TrxA, and TrxC, respectively) by constructing a correspondingly markerless in-frame mutant strain: Δ, Δt, and Δ, respectively. We found that (i) TrxB is confirmed as an intracellular protein, which is different from the prediction made by the Protter illustration; (ii) compared to the wild-type strain, Δ exhibits resistance against HO stress but high sensitivity to thiol-specific diamide stress, while Δ and Δ are moderately sensitive to both HO and diamide conditions; (iii) the deletions of , , and damage 's flagella formation and motility, and plays a decisive role; (iv) deletions of , , and substantially abate bacterial resistance against host serum, especially deletion; (v) and , but not , are involved in bacterial survival and replication in phagocytes; (vi) the thioredoxin system participates in bacterial dissemination in host immune tissues. These findings indicate that the thioredoxin system of plays an important role in stress resistance and virulence, which provides insight into the pathogenic mechanism of .
是一种重要的鱼类病原体，会造成重大经济损失。为了解其致病机制，需要鉴定更多新的毒力因子。细菌硫氧还蛋白系统是主要的二硫键还原酶系统，但其在 中的功能大多未知。在本研究中，我们通过构建相应的无标记框内突变菌株：分别为Δ、Δt和Δ，研究了硫氧还蛋白系统在 （分别命名为TrxB、TrxA和TrxC）中的作用。我们发现：（i）TrxB被确认为一种细胞内蛋白，这与Protter图示的预测不同；（ii）与野生型菌株相比，Δ对HO应激具有抗性，但对硫醇特异性二酰胺应激高度敏感，而Δ和Δ对HO和二酰胺条件均中度敏感；（iii）、和的缺失破坏了 的鞭毛形成和运动能力，且 起决定性作用；（iv）、和的缺失显著降低了细菌对宿主血清的抗性，尤其是 缺失；（v）和 而非 参与细菌在吞噬细胞中的存活和复制；（vi）硫氧还蛋白系统参与细菌在宿主免疫组织中的传播。这些发现表明， 的硫氧还蛋白系统在抗应激和毒力方面发挥重要作用，这为了解 的致病机制提供了线索。
