PDBsum entry 1m7t

Electron transport

PDB id: 1m7t

Contents

Protein chain

107 a.a. *

* Residue conservation analysis

PDB id:

1m7t

Name:

Electron transport

Title:

Solution structure and dynamics of the human-escherichia coli thioredoxin chimera: insights into thermodynamic stability

Structure:

Chimera of human and e. Coli thioredoxin. Chain: a. Engineered: yes. Other_details: chimera consists of residues 1-66 from human, residues 67-107 from e. Coli.

Source:

Homo sapiens, escherichia coli. Organism_taxid: 9606,562. Expressed in: escherichia coli. Expression_system_taxid: 469008.

NMR struc:

21 models

Authors:

B.Dangi,A.V.Dobrodumov,J.M.Louis,A.M.Gronenborn

Key ref:

B.Dangi et al. (2002). Solution structure and dynamics of the human-Escherichia coli thioredoxin chimera: insights into thermodynamic stability. Biochemistry, 41, 9376-9388. PubMed id: 12135359 DOI: 10.1021/bi0258501

Date:

22-Jul-02 Release date: 25-Sep-02

Protein chain

P0AA25  (THIO_ECOLI) -  Thioredoxin 1 from Escherichia coli (strain K12)

Seq: 109 a.a.

Struc: 107 a.a.*

Protein chain

P10599  (THIO_HUMAN) -  Thioredoxin from Homo sapiens

Seq: 105 a.a.

Struc: 107 a.a.*

* PDB and UniProt seqs differ at 76 residue positions (black crosses)

DOI no: 10.1021/bi0258501

Biochemistry 41:9376-9388 (2002)

PubMed id: 12135359

Solution structure and dynamics of the human-Escherichia coli thioredoxin chimera: insights into thermodynamic stability.

B.Dangi, A.V.Dobrodumov, J.M.Louis, A.M.Gronenborn.

ABSTRACT

We have determined the high-resolution solution structure of the oxidized form of a chimeric human and Escherichia coli thioredoxin (TRX(HE)) by NMR. The overall structure is well-defined with a rms difference for the backbone atoms of 0.27 +/- 0.06 A. The topology of the protein is identical to those of the human and E. coli parent proteins, consisting of a central five-stranded beta-sheet surrounded by four alpha-helices. Analysis of the interfaces between the two domains derived from the human and E. coli sequences reveals that the general hydrophobic packing is unaltered and only subtle changes in the details of side chain interactions are observed. The packing of helix alpha(4) with helix alpha(2) across the hybrid interface is less optimal than in the parent molecules, and electrostatic interactions between polar side chains are missing. In particular, lysine-glutamate salt bridges between residues on helices alpha(2) and alpha(4), which were observed in both human and E. coli proteins, are not present in the chimeric protein. The origin of the known reduced thermodynamic stability of TRX(HE) was probed by mutagenesis on the basis of these structural findings. Two mutants of TRX(HE), S44D and S44E, were created, and their thermal and chemical stabilities were examined. Improved stability toward chaotropic agents was observed for both mutants, but no increase in the denaturation temperature was seen compared to that of TRX(HE). In addition to the structural analysis, the backbone dynamics of TRX(HE) were investigated by (15)N NMR relaxation measurements. Analysis using the model free approach reveals that the protein is fairly rigid with an average S(2) of 0.88. Increased mobility is primarily present in two external loop regions comprising residues 72-74 and 92-94 that contain glycine and proline residues.