PDBsum entry: 2ipa

Electron transport/oxidoreductase

PDB id: 2ipa

Contents

Protein chains

104 a.a. *

139 a.a. *

* Residue conservation analysis

PDB id:

2ipa

Name:

Electron transport/oxidoreductase

Title:

Solution structure of trx-arsc complex

Structure:

Thioredoxin. Chain: a. Synonym: trx. Engineered: yes. Mutation: yes. Protein arsc. Chain: b. Synonym: arsenate reductase, arsenical pump modifier, low molecular weight protein-tyrosine-phosphatase.

Source:

Bacillus subtilis. Organism_taxid: 1423. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

NMR struc:

21 models

Authors:

C.Jin,Y.Hu,Y.Li,X.Zhang

Key ref:

Y.Li et al. (2007). Conformational fluctuations coupled to the thiol-disulfide transfer between thioredoxin and arsenate reductase in Bacillus subtilis. J Biol Chem, 282, 11078-11083. PubMed id: 17303556 DOI: 10.1074/jbc.M700970200

Date:

12-Oct-06 Release date: 13-Feb-07

Protein chain

P14949  (THIO_BACSU) -  Thioredoxin

Seq: 104 a.a.

Struc: 104 a.a.*

Protein chain

P45947  (ARSC_BACSU) -  Protein ArsC

Seq: 139 a.a.

Struc: 139 a.a.*

* PDB and UniProt seqs differ at 4 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chain B: E.C.3.1.3.48 - Protein-tyrosine-phosphatase.
• Reaction: Protein tyrosine phosphate + H₂O = protein tyrosine + phosphate

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

 Gene Ontology (GO) functional annotation 

• Biological process: oxidation reduction (7 terms)
• Biochemical function: electron carrier activity (6 terms)

reference

DOI no: 10.1074/jbc.M700970200

J Biol Chem 282:11078-11083 (2007)

PubMed id: 17303556

Conformational fluctuations coupled to the thiol-disulfide transfer between thioredoxin and arsenate reductase in Bacillus subtilis.

Y.Li, Y.Hu, X.Zhang, H.Xu, E.Lescop, B.Xia, C.Jin.

ABSTRACT

Arsenic compounds commonly exist in nature and are toxic to nearly all kinds of life forms, which directed the evolution of enzymes in many organisms for arsenic detoxification. In bacteria, the thioredoxin-coupled arsenate reductase catalyzes the reduction of arsenate to arsenite by intramolecular thiol-disulfide cascade. The oxidized arsenate reductase ArsC is subsequently regenerated by thioredoxin through an intermolecular thiol-disulfide exchange process. The solution structure of the Bacillus subtilis thioredoxin-arsenate reductase complex represents the transiently formed intermediate during the intermolecular thiol-disulfide exchange reaction. A comparison of the complex structure with that of thioredoxin and arsenate reductase proteins in redox states showed substantial conformational changes coupled to the reaction process, with arsenate reductase, especially, adopting an "intermediate" conformation in the complex. Our current studies provide novel insights into understanding the reaction mechanisms of the thioredoxin-arsenate reductase pathway.

Selected figure(s)

Figure 1.
Solution structure of the Trx-ArsC complex.A, superimposition of the 20 lowest energy structures and a ribbon diagram of the Trx-ArsC complex. The sulfur atoms that form the intermolecular disulfide bridge are presented as yellow balls. The side chains of residues with unambiguously observed intermolecular NOEs are presented in stick format in a ribbon representation. B, enlarged view of the Trx-ArsC interface at two different angles. The backbone conformation of the residues at the interface is shown in stick representation. The side chains of ArsC-Met^91 and Trx-Met^70 are also shown and labeled. C and D, the molecular surface representations of c-Trx (C) and c-ArsC (D) with the interacting peptide segments of the other protein presented in stick format. The N- and C-terminal ends of the long segments are labeled. The backbones of the segments are colored in green; the side chains of positively and negatively charged residues are colored in blue and red, respectively; other side chains are colored in yellow. The sulfur atoms of the peptide segments involved in the disulfide bridge are also shown.

Figure 2.
Structural comparison of ArsC and Trx at different states.A, ribbon representations of Trx structures, colored as follows: re-Trx, red; c-Trx, light green; ox-Trx, light blue; the segment Cys^29–Cys^32 (Cys^29–Ser^32 in c-Trx), violet; the segment that involves in interaction with ArsC (including the helix Gln^61–Lys^66 and the following loop, Met^70–Ile^72), yellow. The two active cysteines (serines in c-Trx) and residue Val^88 are presented and labeled. B, the conformational changes near the active site (segments 24–34 and 57–73) in Trx, colored as follows: re-Trx, red; c-Trx, light green; ox-Trx, light blue. The side chains of selected residues are presented in stick format and labeled. The ends of the segments are labeled by numbers. The movements of selected residues are shown by curved arrows. C, ribbon representations of ArsC structures, colored as follows: ox-ArsC, light blue; c-ArsC, light green; re-ArsC, red; the P-loop (Cys^10–Cys^15), violet; the extended segment containing Cys^89 and involved in interaction with Trx, yellow. The three active cysteines (serines in c-ArsC) are presented and labeled. The short helix Ser^69–Leu^72 is also labeled. D, the conformational switches of segment 80–99 in ArsC, colored as follows: ox-ArsC, light blue; c-ArsC, light green; re-ArsC, red. The side chains of selected residues are presented in stick format and labeled. The ends of the segment are labeled by numbers. The movements of selected residues are shown by curved arrows. The proteins in different states are arranged in A and C from left to right following the stages of the enzymatic reaction.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2007, 282, 11078-11083) copyright 2007.