PDBsum entry 1a2m

Oxidoreductase

PDB id: 1a2m

Contents

Protein chains

188 a.a. *

Waters ×25

* Residue conservation analysis

PDB id:

1a2m

Name:

Oxidoreductase

Title:

Oxidized dsba at 2.7 angstroms resolution, crystal form iii

Structure:

Disulfide bond formation protein. Chain: a, b. Synonym: dsba. Engineered: yes

Source:

Escherichia coli. Organism_taxid: 562. Cellular_location: periplasm. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.70Å R-factor: 0.261 R-free: 0.308

Authors:

J.L.Martin,L.W.Guddat

Key ref:

L.W.Guddat et al. (1998). Crystal structures of reduced and oxidized DsbA: investigation of domain motion and thiolate stabilization. Structure, 6, 757-767. PubMed id: 9655827 DOI: 10.1016/S0969-2126(98)00077-X

Date:

06-Jan-98 Release date: 08-Jul-98

Protein chains

P0AEG4  (DSBA_ECOLI) -  Thiol:disulfide interchange protein DsbA from Escherichia coli (strain K12)

Seq: 208 a.a.

Struc: 188 a.a.

DOI no: 10.1016/S0969-2126(98)00077-X

Structure 6:757-767 (1998)

PubMed id: 9655827

Crystal structures of reduced and oxidized DsbA: investigation of domain motion and thiolate stabilization.

L.W.Guddat, J.C.Bardwell, J.L.Martin.

ABSTRACT

BACKGROUND: The redox proteins that incorporate a thioredoxin fold have diverse properties and functions. The bacterial protein-folding factor DsbA is the most oxidizing of the thioredoxin family. DsbA catalyzes disulfide-bond formation during the folding of secreted proteins. The extremely oxidizing nature of DsbA has been proposed to result from either domain motion or stabilizing active-site interactions in the reduced form. In the domain motion model, hinge bending between the two domains of DsbA occurs as a result of redox-related conformational changes. RESULTS: We have determined the crystal structures of reduced and oxidized DsbA in the same crystal form and at the same pH (5.6). The crystal structure of a lower pH form of oxidized DsbA has also been determined (pH 5.0). These new crystal structures of DsbA, and the previously determined structure of oxidized DsbA at pH 6.5, provide the foundation for analysis of structural changes that occur upon reduction of the active-site disulfide bond. CONCLUSIONS: The structures of reduced and oxidized DsbA reveal that hinge bending motions do occur between the two domains. These motions are independent of redox state, however, and therefore do not contribute to the energetic differences between the two redox states. Instead, the observed domain motion is proposed to be a consequence of substrate binding. Furthermore, DsbA's highly oxidizing nature is a result of hydrogen bond, electrostatic and helix-dipole interactions that favour the thiolate over the disulfide at the active site.

Selected figure(s)

Figure 4.
Figure 4. Symmetry-related contact in the OX2 crystal structure at the proposed peptide-binding groove of DsbA. The groove is formed between the active-site helix (a1) on the left and the b5 strand-loop-a7 helix on the right. The symmetry-related atoms Ser128^*-Phe129^*-Val130^* are shown in a blue ball-and-stick representation, with Phe129^* labeled (F129^*). The active-site Cys30 sulfur atom is shown as a yellow CPK sphere. This figure was generated using MOLSCRIPT v2.0.1 [52] and Raster3D [53 and 54].

The above figure is reprinted by permission from Cell Press: Structure (1998, 6, 757-767) copyright 1998.

Figure was selected by the author.