PDBsum entry: 1ep8

Electron transport

PDB id: 1ep8

Contents

Protein chains

112 a.a. *

Waters ×44

* Residue conservation analysis

PDB id:

1ep8

Name:

Electron transport

Title:

Crystal structure of a mutated thioredoxin, d30a, from chlamydomonas reinhardtii

Structure:

Thioredoxin ch1, h-type. Chain: a, b. Engineered: yes. Mutation: yes

Source:

Chlamydomonas reinhardtii. Organism_taxid: 3055. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.20Å R-factor: 0.196 R-free: 0.220

Authors:

V.Menchise,C.Corbier,C.Didierjean,M.Saviano,E.Benedetti, J.P.Jacquot,A.Aubry

Key ref:

V.Menchise et al. (2001). 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. PubMed id: 11563970 DOI: 10.1042/0264-6021:3590065

Date:

28-Mar-00 Release date: 12-Dec-01

Protein chains

P80028  (TRXH_CHLRE) -  Thioredoxin H-type

Seq: 113 a.a.

Struc: 112 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

 Gene Ontology (GO) functional annotation 

• Cellular component: cytoplasm (1 term)
• Biological process: transport (3 terms)

DOI no: 10.1042/0264-6021:3590065

Biochem J 359:65-75 (2001)

PubMed id: 11563970

Crystal structure of the wild-type and D30A mutant thioredoxin h of Chlamydomonas reinhardtii and implications for the catalytic mechanism.

V.Menchise, C.Corbier, C.Didierjean, M.Saviano, E.Benedetti, J.P.Jacquot, A.Aubry.

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.