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2bk6

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[[Image:2bk6.gif|left|200px]]
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{{STRUCTURE_2bk6| PDB=2bk6 | SCENE= }}
{{STRUCTURE_2bk6| PDB=2bk6 | SCENE= }}
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'''THE X-RAY CRYSTAL STRUCTURE OF THE LISTERIA INNOCUA H31G DPS MUTANT.'''
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===THE X-RAY CRYSTAL STRUCTURE OF THE LISTERIA INNOCUA H31G DPS MUTANT.===
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==Overview==
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The role of the ferroxidase center in iron uptake and hydrogen peroxide detoxification was investigated in Listeria innocua Dps by substituting the iron ligands His31, His43, and Asp58 with glycine or alanine residues either individually or in combination. The X-ray crystal structures of the variants reveal only small alterations in the ferroxidase center region compared to the native protein. Quenching of the protein fluorescence was exploited to assess stoichiometry and affinity of metal binding. Substitution of either His31 or His43 decreases Fe(II) affinity significantly with respect to wt L. innocua Dps (K approximately 10(5) vs approximately 10(7) M(-)(1)) but does not alter the binding stoichiometry [12 Fe(II)/dodecamer]. In the H31G-H43G and H31G-H43G-D58A variants, binding of Fe(II) does not take place with measurable affinity. Oxidation of protein-bound Fe(II) increases the binding stoichiometry to 24 Fe(III)/dodecamer. However, the extent of fluorescence quenching upon Fe(III) binding decreases, and the end point near 24 Fe(III)/dodecamer becomes less distinct with increase in the number of mutated residues. In the presence of dioxygen, the mutations have little or no effect on the kinetics of iron uptake and in the formation of micelles inside the protein shell. In contrast, in the presence of hydrogen peroxide, with increase in the number of substitutions the rate of iron oxidation and the capacity to inhibit Fenton chemistry, thereby protecting DNA from oxidative damage, appear increasingly compromised, a further indication of the role of ferroxidation in conferring peroxide tolerance to the bacterium.
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{{ABSTRACT_PUBMED_15823016}}
==About this Structure==
==About this Structure==
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[[Category: Metal transport]]
[[Category: Metal transport]]
[[Category: Mutagenesis study]]
[[Category: Mutagenesis study]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 20:24:05 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 23:18:31 2008''

Revision as of 20:18, 28 July 2008

Image:2bk6.png

Template:STRUCTURE 2bk6

THE X-RAY CRYSTAL STRUCTURE OF THE LISTERIA INNOCUA H31G DPS MUTANT.

Template:ABSTRACT PUBMED 15823016

About this Structure

2BK6 is a Single protein structure of sequence from Listeria innocua. Full crystallographic information is available from OCA.

Reference

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., Ilari A, Latella MC, Ceci P, Ribacchi F, Su M, Giangiacomo L, Stefanini S, Chasteen ND, Chiancone E, Biochemistry. 2005 Apr 19;44(15):5579-87. PMID:15823016

Page seeded by OCA on Mon Jul 28 23:18:31 2008

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