Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, PR China.
Fish Shellfish Immunol. 2011 Dec;31(6):985-92. doi: 10.1016/j.fsi.2011.08.018. Epub 2011 Sep 5.
DNA-binding protein from starved cells (Dps) is a member of ferritin-like proteins that exhibit properties of nonspecific DNA binding and iron oxidation and storage. Although studies of Dps from many bacterial species have been reported, no investigations on Dps from fish pathogens have been documented. In this study, we examined the biological function of two Dps proteins, Dps1 and Dps2, from Edwardsiella tarda, an important fish bacterial pathogen that can also infect humans. Dps1 and Dps2 are, respectively, 163- and 174-residue in length and each contains the conserved ferroxidase center of Dps. Expression of dps1 and dps2 was growth phase-dependent and reached high levels in stationary phase. Purified recombinant Dps1 and Dps2 were able to mediate iron oxidation by H(2)O(2) and bind DNA. Compared to the wild type strain, (i) the dps1 mutant (TXDps1) and the dps2 mutant (TXDps2) were unaffected in growth, while the dps2 mutant with interfered dps1 expression (TXDps2RI) exhibited a prolonged lag phase; (ii) TXDps1, TXDps2, and especially TXDps2RI were significantly reduced in H(2)O(2) and UV tolerance and impaired in the capacity to invade into host tissues and replicate in head kidney macrophages; (iii) TXDps1, TXDps2, and TXDps2RI induced stronger macrophage respiratory burst activity and thus were defective in the ability to block the bactericidal response of macrophages. Taken together, these results indicate that Dps1 and Dps2 are functional analogues that possess ferroxidase activity and DNA binding capacity and are required for optimum oxidative stress resistance and full bacterial virulence.
饥饿细胞 DNA 结合蛋白（Dps）是铁蛋白样蛋白家族的成员，具有非特异性 DNA 结合和铁氧化及储存功能。尽管已经报道了许多细菌物种的 Dps 研究，但尚未有关于鱼类病原体 Dps 的研究。在本研究中，我们研究了爱德华氏菌（一种重要的鱼类细菌性病原体，也可感染人类）中两种 Dps 蛋白（Dps1 和 Dps2）的生物学功能。Dps1 和 Dps2 分别长 163 和 174 个残基，每个都包含 Dps 的保守亚铁氧化酶中心。dps1 和 dps2 的表达与生长阶段有关，在静止期达到高水平。纯化的重组 Dps1 和 Dps2 能够介导 H2O2 氧化铁并结合 DNA。与野生型菌株相比，（i）dps1 突变体（TXDps1）和 dps2 突变体（TXDps2）在生长过程中不受影响，而干扰 dps1 表达的 dps2 突变体（TXDps2RI）表现出延长的迟滞期；（ii）TXDps1、TXDps2 特别是 TXDps2RI 在 H2O2 和 UV 耐受性方面显著降低，并且在入侵宿主组织和在头肾巨噬细胞中复制的能力受损；（iii）TXDps1、TXDps2 和 TXDps2RI 诱导更强的巨噬细胞呼吸爆发活性，因此在阻止巨噬细胞杀菌反应的能力上存在缺陷。综上所述，这些结果表明 Dps1 和 Dps2 是功能类似物，具有亚铁氧化酶活性和 DNA 结合能力，是最佳氧化应激抗性和完全细菌毒力所必需的。
