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 O 2 as efficient iron oxidant. The reaction stoichiometry is 3-4 O 2:Fe(II) as in all bacterial ferritins. Accordingly no H 2O 2 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. © 2011 Springer.
The characterization of Thermotoga maritima ferritin reveals an unusual subunit dissociation behavior and efficient DNA protection from iron-mediated oxidative stress / Ceci, Pierpaolo; Forte, Elena; G., Di Cecca; Fornara, Manuela; Chiancone, Emilia. - In: EXTREMOPHILES. - ISSN 1431-0651. - 15:3(2011), pp. 431-439. [10.1007/s00792-011-0374-3]
The characterization of Thermotoga maritima ferritin reveals an unusual subunit dissociation behavior and efficient DNA protection from iron-mediated oxidative stress
CECI, Pierpaolo;FORTE, Elena;FORNARA, MANUELA;CHIANCONE, Emilia
2011
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 O 2 as efficient iron oxidant. The reaction stoichiometry is 3-4 O 2:Fe(II) as in all bacterial ferritins. Accordingly no H 2O 2 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. © 2011 Springer.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.