Objective To investigate the effects of ferric uptake regulator (Fur) on iron homeostasis, oxidative stress response, and virulence in Vibrio parahaemolyticus. Methods BLASTp and multiple sequence alignment analyses were employed to analyze the conservation of Fur proteins in several Gram-negative bacteria. A fur gene deletion mutant (Δfur) and a complementation strain (CΔfur) were constructed. The growth of the wild-type (WT), Δfur, and CΔfur was compared under normal (iron-replete), iron-excess, iron-restricted, and oxidative stress conditions. Inductively coupled plasma mass spectrometry was employed to measure intracellular metal content in each strain. A zebrafish survival assay and a competition infection assay were performed to assess the impact of Fur on the virulence of V. parahaemolyticus. RNA sequencing was conducted to identify the genes regulated by Fur. Results The Fur proteins were highly conserved among several Gram-negative bacteria. The deletion of fur attenuated the growth of V. parahaemolyticus under normal (iron-replete) and iron-excess conditions, and reduced its sensitivity to iron restriction. The intracellular iron content in Δfur was significantly lower than that in the WT and CΔfur strains. Fur regulated the oxidative stress response in V. parahaemolyticus. Fur played no significant role in the virulence of V. parahaemolyticus in the zebrafish model. The expression of multiple genes related to iron uptake, iron storage, and type Ⅲ secretion system 1 (T3SS1) was significantly upregulated, whereas genes encoding iron-containing proteins and type Ⅵ secretion system 2 (T6SS2) components were significantly downregulated in Δfur. Conclusion Fur regulates iron homeostasis and oxidative stress response in V. parahaemolyticus, but does not affect its virulence in zebrafish.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |