1wb7

File:1wb7.jpg

spinqualitylabelsall models 1wb7, resolution 2.24Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

IRON SUPEROXIDE DISMUTASE (FE-SOD) FROM THE HYPERTHERMOPHILE SULFOLOBUS SOLFATARICUS. CRYSTAL STRUCTURE OF THE Y41F MUTANT.

OverviewOverview

We have examined and compared the effects of mutating Y41 and H155 in the, iron superoxide dismutase (SOD) from the archaeon Sulfolobus solfataricus, (Ss). These two neighboring residues in the active site are known to have, crucial functions in structurally related SODs from different sources. The, metal analysis indicates a slightly lower iron content after either Y41F, or H155Q replacement, without any significant substitution of iron for, manganese. The specific activity of SsSOD referred to the iron content is, 17-fold reduced in the Y41F mutant, whereas it is less than 2-fold reduced, by the H155Q mutation. The noticeable pH dependence of the activity of, SsSOD and H155Q-SsSOD, due to the ionization of Y41 (pK 8.4), is lost in, Y41F-SsSOD. After H155Q and even more after the Y41F substitution, the, archaeal enzyme acquires a moderate sensitivity to sodium azide, inhibition. The hydrogen peroxide inactivation of SsSOD is significantly, increased after H155Q replacement; however, both mutants are insensitive, to the modification of residue 41 by phenylmethanesulfonyl fluoride. Heat, inactivation studies showed that the high stability of SsSOD is reduced by, the H155Q mutation; however, upon the addition of SDS, a much faster, inactivation kinetics is observed both with wild-type and mutant SsSOD, forms. The detergent is also required to follow thermal denaturation of, the archaeal enzyme by Fourier transform infrared spectroscopy; these, studies gave information about the effect of mutations and modification on, flexibility and compactness of the protein structure. The crystal, structure of Y41F mutant revealed an uninterrupted hydrogen bond network, including three solvent molecules connecting the iron-ligating hydroxide, ion via H155 with F41 and H37, which is not present in structures of the, corresponding mutant SODs from other sources. These data suggest that Y41, and H155 are important for the structural and functional properties of, SsSOD; in particular, Y41 seems to be a powerful regulator of the activity, of SsSOD, whereas H155 is apparently involved in the organization of the, active site of the enzyme.

About this StructureAbout this Structure

1WB7 is a Single protein structure of sequence from Sulfolobus solfataricus with FE as ligand. Active as Superoxide dismutase, with EC number 1.15.1.1 Known structural/functional Site: . Full crystallographic information is available from OCA.

ReferenceReference

The role of Tyr41 and His155 in the functional properties of superoxide dismutase from the archaeon Sulfolobus solfataricus., Gogliettino MA, Tanfani F, Scire A, Ursby T, Adinolfi BS, Cacciamani T, De Vendittis E, Biochemistry. 2004 Mar 2;43(8):2199-208. PMID:14979716

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