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Your search keyword '"Stefanini, Simonetta"' showing total 48 results
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48 results on '"Stefanini, Simonetta"'

8. The unusual intersubunit ferroxidase center of Listeria innocua Dps is required for hydrogen peroxide detoxification but not for iron uptake: A study with site-specific mutants

Author

Ilari, Andrea, Latella, Maria Carmela, Chiancone, Emilia, Ceci, Pierpaolo, Ribacchi, Federica, Meihong Su, Giangiacomo, Laura, Stefanini, Simonetta, and Chasteen, N. Dennis

Subjects
Hydrogen peroxide -- Chemical properties, DNA binding proteins -- Structure, DNA binding proteins -- Chemical properties, Oxidases -- Analysis, Biological sciences, Chemistry
Abstract

The role of the ferroxidase center in iron uptake and hydrogen peroxide detoxification is investigated in Listeria innocua DNA binding protein from starved cells (LiDps). It is concluded that the behavior of the ferroxidase center variants of LiDps show that an intact ferroxidase center is not required when the bacterium is in an aerobic environment.

Published
2005

9. The so-called Listeria innocua Ferritin is a Dps protein: Iron incorporation, detoxification, and DNA protection properties

Author

Meihong Su, Cavallo, Stefano, Stefanini, Simonetta, Chiancone, Emilia, and Chasteen, N. Dennis

Subjects
DNA binding proteins -- Structure, DNA binding proteins -- Chemical properties, Listeria -- Research, Biological sciences, Chemistry
Abstract

The chemistry of iron binding and oxidation in Listeria innocua DNA binding protein from starved cells (LiDps) is studied using H(sub 2)O(sub 2) as oxidant to further define the mechanism of iron deposition inside the protein and the role of LiDps in protecting DNA from oxidative damage. It is concluded that the reactions occur in place of undesirable odd-electron redox processes that produce hydroxyl radical.

Published
2005

15. Formation and movement of Fe(III) in horse spleen, H- and L-recombinant ferritins. A fluorescence study

Author

Cavallo, Stefano, Mei, G., Stefanini, Simonetta, Rosato, N., Finazzi Agro', A., and Chiancone, Emilia

Subjects
iron incorporation, ferritin, steady-state and time resolved fluorescence, Recombinant Proteins, steady-state and time-resolved fluorescence, Kinetics, Biopolymers, Spectrometry, Fluorescence, Ferritins, Animals, Humans, Horses, Spleen, Research Article
Abstract

Iron oxidation and incorporation into apoferritins of different subunit composition, namely the recombinant H and L homopolymers and the natural horse spleen heteropolymer (10-15% H), have been followed by steady-state and time-resolved fluorescence. After aerobic addition of 100 Fe(II) atoms/polymer, markedly different kinetic profiles are observed. In the rL-homopolymer a slow monotonic fluorescence quenching is observed which reflects binding, slow oxidation at the threefold apoferritin channels, and diffusion into the protein cavity. In the rH-homopolymer a fast fluorescence quenching is followed by a partial, slow recovery. The two processes have been attributed to Fe(II) binding and oxidation at the ferroxidase centers and to Fe(III) released into the cavity, respectively. The fluorescence kinetics of horse spleen apoferritin is dominated by the H chain contribution and resembles that of the H homopolymer. It brings out clearly that the rate of the overall process is limited by the rate at which Fe(III) leaves the ferroxidase centers of the H chains where binding of incoming Fe(II) and its oxidation take place. The data obtained upon stepwise addition of iron and the results of optical absorption measurements confirm this picture. The correspondence between steady-state and time-resolved data is remarkably good; this is manifest when the latter are used to calculate the change in fluorescence intensity as apparent in the steady-state measurements.

Published
1998

34. The dodecameric ferritin from Listeria innocua contains a novel intersubunit iron-binding site.

Author

Ilari, Andrea, Stefanini, Simonetta, Chiancone, Emilia, and Tsernoglou, Demetrius

Subjects
*FERRITIN, *BINDING sites, *POLYMERS
Abstract

Ferritin is characterized by a highly conserved architecture that comprises 24 subunits assembled into a spherical cage with 432 symmetry. The only known exception is the dodecameric ferritin from Listeria innocua. The structure of Listeria ferritin has been determined to a resolution of 2.35 Å by molecular replacement, using as a search model the structure of Dps from Escherichia coli. The Listeria 12-mer is endowed with 23 symmetry and displays the functionally relevant structural features of the ferritin 24-mer, namely the negatively charged channels along the three-fold symmetry axes that serve for iron entry into the cavity and a negatively charged internal cavity for iron deposition. The electron density map shows 12 iron ions on the inner surface of the hollow core, at the interface between monomers related by two-fold axes. Analysis of the nature and stereochemistry of the iron-binding ligands reveals strong similarities with known ferroxidase sites. The L. innocua ferritin site, however, is the first described so far that has ligands belonging to two different subunits and is not contained within a four-helix bundle. [ABSTRACT FROM AUTHOR]

Published
2000

48. The mutations Lys 114 --> Gln and Asp 126 --> Asn disrupt an intersubunit salt bridge and convert Listeria innocua Dps into its natural mutant Listeria monocytogenes Dps. Effects on protein stability at Low pH.

Author

Bellapadrona G, Chiaraluce R, Consalvi V, Ilari A, Stefanini S, and Chiancone E

Subjects
Amino Acids genetics, Bacterial Proteins genetics, Chromatography, Gel, Circular Dichroism, Crystallography, X-Ray, DNA-Binding Proteins genetics, Hydrogen-Ion Concentration, Kinetics, Listeria genetics, Models, Molecular, Mutation genetics, Protein Binding, Protein Denaturation, Protein Folding, Protein Structure, Quaternary, Protein Structure, Tertiary, Protein Subunits chemistry, Protein Subunits genetics, Protein Subunits metabolism, Solutions, Temperature, Amino Acids metabolism, Bacterial Proteins chemistry, Bacterial Proteins metabolism, DNA-Binding Proteins chemistry, DNA-Binding Proteins metabolism, Listeria chemistry, Listeria metabolism, Salts
Abstract

The stability of the dodecameric Listeria monocytogenes Dps has been compared with that of the Listeria innocua protein. The two proteins differ only in two amino acid residues that form an intersubunit salt-bridge in L. innocua Dps. This salt-bridge is replaced by a hydrogen bonding network in L. monocytogenes Dps as revealed by the X-ray crystal structure. The resistance to low pH and high temperature was assayed for both Dps proteins under equilibrium conditions and kinetically. Despite the identical equilibrium behavior, significant differences in the kinetic stability and activation energy of the unfolding process are apparent at pH 1.5. The higher stability of L. monocytogenes Dps has been accounted for in terms of the persistence of the hydrogen bonding network at this low pH value. In contrast, the salt-bridge between Lys 114 and Asp 126 characteristic of L. innocua Dps is most likely abolished due to protonation of Asp 126., ((c) 2006 Wiley-Liss, Inc.)

Published
2007
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