Overexpression and Characterization of an Iron Storage and DNA-Binding Dps Protein from Trichodesmium erythraeum

Abstract

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 N 2 -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 T. erythraeurm protein (Dps tery ) with 69% primary amino acid sequence similarity to Synechococcus DpsA. We expressed and purified Dps tery , and we found that Dps tery , like other Dps proteins, is able to bind Fe and DNA and protect DNA from degradation by DNase. We also found that Dps tery binds phosphate, like other ferritin family proteins. Fe K near-edge X-ray absorption of Dps tery indicated that it has an iron core that resembles that of horse spleen ferritin.

Campylobacter jejuni Dps Protein Binds DNA in the Presence of Iron or Hydrogen Peroxide

“…Dps proteins from several organisms can physically interact with DNA (7,22,25,28,45). In this study, we demonstrated that C. jejuni Dps can bind DNA in the presence of Fe 2ϩ or H 2 O 2 using electrophoretic mobility shift and DNase I protection assays ( Fig.…”

“…In all Dps proteins studied, DNA protection is exerted through the removal of free Fe 2ϩ from the solution by reduction of the formation of reactive oxygen species through Fenton chemistry. Furthermore, some Dps proteins can also physically protect DNA through the formation of nonspecific protein-DNA complexes (7,22,(27)(28)(29)(30). The mechanism of DNA binding by Dps proteins is not completely understood (9).…”

Ecological Genomics of Marine Picocyanobacteria

“…Interestingly, the capability for Fe storage (via ferritin/bacterioferritin) and the presence of this potential CRP regulatory protein and several other Fe-related genes, including dpsA (encoding a DNA-binding, ferritin-like protein [42,221]), noticeably differs between members of specific Synechococcus clades (Table 9) (see also the "Photoacclimation and Oxidative Stress" section above). In contrast, the Fe-related gene content for Prochlorococcus appears to be generally more coherent between strains/ecotypes, but even in this genus, differences exist both between the MIT9313/MIT9303 cluster and other Prochlorococcus strains and between MED4 (HLI) and MIT9312 (HLII).…”

Iron conservation by reduction of metalloenzyme inventories in the marine diazotroph Crocosphaera watsonii

“…Field experiments and models both predict the distribution of oceanic nitrogen fixation to be primarily constrained by the availability of iron (2,(9)(10)(11). Despite this importance of iron on marine nitrogen fixation, there is a limited understanding of how marine diazotrophs have adapted to this low iron environment (12)(13)(14)(15)(16)(17).…”