Overexpression and Characterization of an Iron Storage and DNA-Binding Dps Protein from Trichodesmium erythraeum
2006
Castruita, M. | Saito, M. | Schottel, P. C. | Elmegreen, L. A. | Myneni, S. | Stiefel, E. I. | Morel, F. M. M.
Although the role of iron in marine productivity has received a great deal of attention, no iron storage protein has been isolated from a marine microorganism previously. We describe an Fe-binding protein belonging to the Dps family (DNA binding protein from starved cells) in the N₂-fixing marine cyanobacterium Trichodesmium erythraeum. A dps gene encoding a protein with significant levels of identity to members of the Dps family was identified in the genome of T. erythraeum. This gene codes for a putative Dps[subscript T. erythraeurm] protein (Dps[subscript tery]) with 69% primary amino acid sequence similarity to Synechococcus DpsA. We expressed and purified Dps[subscript tery], and we found that Dps[subscript tery], like other Dps proteins, is able to bind Fe and DNA and protect DNA from degradation by DNase. We also found that Dps[subscript tery] binds phosphate, like other ferritin family proteins. Fe K near-edge X-ray absorption of Dps[subscript tery] indicated that it has an iron core that resembles that of horse spleen ferritin.
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