1EP7

CRYSTAL STRUCTURE OF WT THIOREDOXIN H FROM CHLAMYDOMONAS REINHARDTII

Summary for 1EP7

• Entry DOI: 10.2210/pdb1ep7/pdb
• Related: 1EP8
• Descriptor: THIOREDOXIN CH1, H-TYPE (2 entities in total)
• Functional Keywords: electron transport
• Biological source: Chlamydomonas reinhardtii
• Cellular location: Cytoplasm: P80028
• Total number of polymer chains: 2
• Total formula weight: 23455.07

Authors

Menchise, V.,Corbier, C.,Didierjean, C.,Saviano, M.,Benedetti, E.,Jacquot, J.P.,Aubry, A. (deposition date: 2000-03-28, release date: 2001-12-12, Last modification date: 2011-07-13)

Primary citation

Menchise, V.,Corbier, C.,Didierjean, C.,Saviano, M.,Benedetti, E.,Jacquot, J.P.,Aubry, A.
Crystal structure of the wild-type and D30A mutant thioredoxin h of Chlamydomonas reinhardtii and implications for the catalytic mechanism.
Biochem.J., 359:65-75, 2001

PubMed Abstract: 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.

PubMed: 11563970
DOI: 10.1042/0264-6021:3590065

Experimental method

X-RAY DIFFRACTION (2.1 Å)