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Dps from Deinococcus radiodurans : oligomeric forms of Dps1 with distinct cellular functions and Dps2 involved in metal storage
Author(s) -
Santos Sandra P.,
Mitchell Edward P.,
Franquelim Henri G.,
Castanho Miguel A. R. B.,
Abreu Isabel A.,
Romão Célia V.
Publication year - 2015
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13420
Subject(s) - deinococcus radiodurans , dna , deinococcus , chemistry , dimer , biophysics , dodecameric protein , ferrous , biochemistry , oligomer , trimer , hydrogen peroxide , biology , organic chemistry
The DNA binding proteins from starved cells from Deinococcus radiodurans , Dps1‐ DR 2263 and Dps2‐ DRB 0092, have a common overall structure of hollow spherical dodecamers. Their involvement in the homeostasis of intracellular metal and DNA protection was addressed. Our results show that Dr Dps proteins are able to oxidize ferrous to ferric iron by oxygen or hydrogen peroxide. The iron stored inside the hollow sphere cavity is fully released. Furthermore, these proteins are able to store and release manganese, suggesting they can play a role in manganese homeostasis as well. The interaction of Dr Dps with DNA was also addressed. Even though Dr Dps1 binds both linear and coiled DNA , Dr Dps2 preferentially binds to coiled DNA , forming different protein– DNA complexes, as clearly shown by atomic force microscopy. Dr Dps1 (dimer and dodecamer) and Dr Dps2 can protect DNA against reactive oxygen species, although the protection occurs at different Fe to protein ratios. The difference between Dr Dps could be the result of the Dr Dps1 higher iron oxidation rate in the presence of hydrogen peroxide and its higher affinity to bind DNA than in Dr Dps2. Using cellular extracts obtained from D. radiodurans cultures, we showed that Dr Dps1 oligomers observed in in vitro conditions are also present in vivo . This indicates that Dr Dps1 has a structural dynamic plasticity that allows its oligomeric state to change between dimer, trimer and dodecamer. This in turn suggests the existence of a regulation mechanism that modulates the oligomer equilibrium and is dependent on growth stages and environmental conditions.