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Crystal structure of the W35A mutant thioredoxin h from Chlamydomonas reinhardtii: The substitution of the conserved active site Trp leads to modifications in the environment of the two catalytic cysteines
Author(s) -
Menchise V.,
Corbier C.,
Didierjean C.,
Jacquot J. P.,
Benedetti E.,
Saviano M.,
Aubry A.
Publication year - 2000
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/1097-0282(2000)56:1<1::aid-bip1036>3.0.co;2-5
Subject(s) - chlamydomonas reinhardtii , chemistry , active site , residue (chemistry) , thioredoxin , mutant , stereochemistry , catalysis , crystallography , biochemistry , enzyme , gene
The conformational analysis of W35A thioredoxin h from the eukaryotic green alga Chlamydomonas reinhardtii in the solid state has been carried out by x‐ray diffraction, with the aim to clarify the role of Trp in the catalysis. Comparative analysis of W35A mutant with wild‐type (WT) thioredoxin shows that, even if the structural motif of thioredoxin is not perturbed, the substitution of Trp35 by an Ala leads to significant changes in protein conformation near the active site. This rearrangement increases its solvent exposure and explains the change of the pKa values of the catalytic cysteines. The substitution of the Trp residue also influences the crystal packing as well as the recognition ability of thioredoxin. The solid state analysis suggests that the Trp residue has a structural function both to force the active site in the bioactive conformation, and to mediate the protein–protein recognition. © 2001 John Wiley & Sons, Inc. Biopolymers 56: 1–7, 2001