Dps biomineralizing proteins: multifunctional architects of nature

Abstract

<jats:p>Dps proteins are the structural relatives of bacterioferritins and ferritins ubiquitously present in the bacterial and archaeal kingdoms. The ball-shaped enzymes play important roles in the detoxification of ROS (reactive oxygen species), in iron scavenging to prevent Fenton reactions and in the mechanical protection of DNA. Detoxification of ROS and iron chaperoning represent the most archetypical functions of dodecameric Dps enzymes. Recent crystallographic studies of these dodecameric complexes have unravelled species-dependent mechanisms of iron uptake into the hollow spheres. Subsequent functions in iron oxidation at ferroxidase centres are highly conserved among bacteria. Final nucleation of iron as iron oxide nanoparticles has been demonstrated to originate at acidic residues located on the inner surface. Some Dps enzymes are also implicated in newly observed catalytic functions related to the formation of molecules playing roles in bacterium–host cell communication. Most recently, Dps complexes are attracting attention in semiconductor science as biomimetic tools for the technical production of the smallest metal-based quantum nanodots used in nanotechnological approaches, such as memory storage or solar cell development.</jats:p>

Purification of the Campylobacter jejuni Dps protein assisted by its high melting temperature

“…The central core of the Dps dodecamer contains conserved residues that form the ferroxidase center were Fe 2+ is oxidized to Fe 3+ and then stored inside the protein shell as insoluble and non-reactive Fe 2 O 3 [4,5]. The Dps ferroxidase center is the most remarkable signature of the Dps family, it is located at the interface between monomers related by 2-fold symmetry [6].…”

Specificity of Metal Sensing: Iron and Manganese Homeostasis in Bacillus subtilis

“…Fur represses synthesis of the bacillibactin siderophore together with pathways involved in iron uptake (36,37). In the stationary phase, and in response to oxidative stress, excess cytosolic iron may be incorporated into two mini-ferritins, Dps and MrgA (38,39). Fur also indirectly regulates many more genes as mediated by a small RNA (FsrA) in collaboration with FbpA, FbpB, and FbpC (putative RNA chaperones) (40).…”

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

“…These proteins are structurally conserved and widely distributed in prokaryotes (8,9). Unlike typical ferritins that have 24 subunits and 432 symmetry, Dps proteins assemble in a quasispherical dodecamer with 23 symmetry and can store ϳ500 iron atoms (4,10). Furthermore, while in typical ferritins each subunit carries its own ferroxidase center, the ferroxidase centers of Dps are located between the subunits, where two Fe 2ϩ ions bind to form a binuclear iron center (4,11).…”

“…Iron is an essential cofactor for many enzymes, required for both survival and pathogenicity of most bacteria; however, this metal can also lead to the formation of reactive oxygen species under oxidizing conditions (4). In the ferrous form (Fe 2ϩ ), iron can react with hydrogen peroxide to produce very reactive and toxic hydroxyl radicals through the Fenton reaction (H 2 O 2 ϩ Fe 2ϩ ¡ OH Ϫ ϩ OH ⅐ ϩ Fe 3ϩ ).…”

“…Unlike typical ferritins that have 24 subunits and 432 symmetry, Dps proteins assemble in a quasispherical dodecamer with 23 symmetry and can store ϳ500 iron atoms (4,10). Furthermore, while in typical ferritins each subunit carries its own ferroxidase center, the ferroxidase centers of Dps are located between the subunits, where two Fe 2ϩ ions bind to form a binuclear iron center (4,11). A number of in vivo studies have demonstrated that Dps is involved in resistance to a variety of stressful conditions, including reactive oxygen species, UV, ionizing radiation, and thermal and acidic stress (7,(12)(13)(14)(15)(16)(17)(18)(19)(20)(21).…”