2VM2: Crystal Structure Of Barley Thioredoxin H Isoform 1 Crystallized Using Peg As Precipitant

Citation:
Abstract
H-type thioredoxins (Trxs) constitute a particularly large Trx sub-group in higher plants. Here, the crystal structures are determined for the two barley Trx h isoforms, HvTrxh1 and HvTrxh2, in the partially radiation-reduced state to resolutions of 1.7 A, and for HvTrxh2 in the oxidized state to 2.0 A. The two Trxs have a sequence identity of 51% and highly similar fold and active-site architecture. Interestingly, the four independent molecules in the crystals of HvTrxh1 form two relatively large and essentially identical protein-protein interfaces. In each interface, a loop segment of one HvTrxh1 molecule is positioned along a shallow hydrophobic groove at the primary nucleophile Cys40 of another HvTrxh1 molecule. The association mode can serve as a model for the target protein recognition by Trx, as it brings the Met82 Cgamma atom (gamma position as a disulfide sulfur) of the bound loop segment in the proximity of the Cys40 thiol. The interaction involves three characteristic backbone-backbone hydrogen bonds in an antiparallel beta-sheet-like arrangement, similar to the arrangement observed in the structure of an engineered, covalently bound complex between Trx and a substrate protein, as reported by Maeda et al. in an earlier paper. The occurrence of an intermolecular salt bridge between Glu80 of the bound loop segment and Arg101 near the hydrophobic groove suggests that charge complementarity plays a role in the specificity of Trx. In HvTrxh2, isoleucine corresponds to this arginine, which emphasizes the potential for specificity differences between the coexisting barley Trx isoforms.
PDB ID: 2VM2Download
MMDB ID: 64135
PDB Deposition Date: 2008/1/21
Updated in MMDB: 2017/07
Experimental Method:
x-ray diffraction
Resolution: 1.8  Å
Source Organism:
Similar Structures:
Biological Unit for 2VM2: monomeric; determined by author and by software (PQS)
Molecular Components in 2VM2
Label Count Molecule
Protein (1 molecule)
1
Thioredoxin H Isoform 1.
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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