Studies On The Ferritin-Like Dps Proteins Of Edwardsiella Tarda

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. In this study, we examined the biological property and function of two Dps proteins, Dps1 and Dps2, from Edwardsiella tarda, an important fish bacterial pathogen. Recombinant Dps1 and Dps2 purified from Escherichia coli were able to mediate iron oxidation and bind DNA. To examine the functional importance of Dps1 and Dps2, three mutant E. tarda strains were constructed: TXDps1, TXDps2, and TXDps2RI. TXDps1 and TXDps2 bear in-frame deletions of dps1 and dps2 respectively, while TXDps2RI is TXDps2 with the expression of dps1 interfered. Compared to the wild type, TXDps1 and TXDps2 were unaffected in growth, whereas TXDps2RI showed slow growth under various conditions. TXDps1, TXDps2, and especially TXDps2RI were significantly reduced in the ability to resist H2O2 damage and UV irradiation. Virulence analysis showed that TXDps1 and TXDps2 exhibited significant reductions in tissue dissemination and multiplication in macrophages, while TXDps2RI was drastically impaired in the ability to invade into host tissues, and replicate in macrophages. These results demonstrate that Dps1 and Dps2 protein of Edwardsiella tarda play important roles in its antioxidant system, protection ability to DNA and adaptability to bad environment, which may contribute to its resistance to host Immune system and surviving in host cells.