Ceci 2011 Extremophiles
| Ceci P, Forte E, Di Cecca G, Fornara M, Chiancone E (2011) The characterization of Thermotoga maritima ferritin reveals an unusual subunit dissociation behavior and efficient DNA protection from iron-mediated oxidative stress. Extremophiles 15:431-9. |
Ceci P, Forte E, Di Cecca G, Fornara M, Chiancone E (2011) Extremophiles
Abstract: Ferritin from the hyperthermophilic anaerobe Thermotoga maritima, a bacterium of ancient phylogenetic origin, is structurally similar to known bacterial and eukaryotic ferritins: 24 identical subunits assemble into a shell having octahedral symmetry and a Mr of about 460 kDa. T. maritima ferritin (TmFtn), purified to homogeneity as a recombinant protein, contains approximately 2-3 iron atoms and can incorporate efficiently up to 3,500 atoms in the form of a ferric oxy-hydroxide mineral at 80 °C, the optimal growth temperature of the bacterium. The 24-mer unexpectedly dissociates reversibly into dimers at low ionic strengths. In turn, dimers re-associate into the native 24-mer assembly at high protein concentrations and upon incorporation of iron micelles containing at least 500 Fe(III). TmFtn uses O2 as efficient iron oxidant. The reaction stoichiometry is 3-4 O2:Fe(II) as in all bacterial ferritins. Accordingly no H2O2 is released into solution, a feature reflected in the in vitro ability of TmFtn to reduce significantly iron-mediated oxidative damage to DNA at 80 °C. A similar TmFtn-mediated ROS detoxifying role likely occurs in the bacterium which lacks the SOD/catalase defense systems of the aerobic world. • Keywords: Thermotoga maritima ferritin, Subunit association-dissociation properties, Iron incorporation, DNA protection, ROS detoxification
Labels:
Organism: Rat, Eubacteria
Preparation: Enzyme
HRR: Oxygraph-2k
