1ep7
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CRYSTAL STRUCTURE OF WT THIOREDOXIN H FROM CHLAMYDOMONAS REINHARDTII
OverviewOverview
Thioredoxins are ubiquitous proteins which catalyse the reduction of, disulphide bridges on target proteins. The catalytic mechanism proceeds, via a mixed disulphide intermediate whose breakdown should be enhanced by, the involvement of a conserved buried residue, Asp-30, as a base catalyst, towards residue Cys-39. We report here the crystal structure of wild-type, and D30A mutant thioredoxin h from Chlamydomonas reinhardtii, which, constitutes the first crystal structure of a cytosolic thioredoxin, isolated from a eukaryotic plant organism. The role of residue Asp-30 in, catalysis has been revisited since the distance between the carboxylate, OD1 of Asp-30 and the sulphur SG of Cys-39 is too great to support the, hypothesis of direct proton transfer. A careful analysis of all available, crystal structures reveals that the relative positioning of residues, Asp-30 and Cys-39 as well as hydrophobic contacts in the vicinity of, residue Asp-30 do not allow a conformational change sufficient to bring, the two residues close enough for a direct proton transfer. This suggests, that protonation/deprotonation of Cys-39 should be mediated by a water, molecule. Molecular-dynamics simulations, carried out either in vacuo or, in water, as well as proton-inventory experiments, support this, hypothesis. The results are discussed with respect to biochemical and, structural data.
About this StructureAbout this Structure
1EP7 is a Single protein structure of sequence from Chlamydomonas reinhardtii. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of the wild-type and D30A mutant thioredoxin h of Chlamydomonas reinhardtii and implications for the catalytic mechanism., Menchise V, Corbier C, Didierjean C, Saviano M, Benedetti E, Jacquot JP, Aubry A, Biochem J. 2001 Oct 1;359(Pt 1):65-75. PMID:11563970
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