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Crystal structure of thioredoxin-2 from Anabaena
M Saarinen1, F K Gleason, H Eklund
1Department of Molecular Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Structure (London, England : 1993)
|October 15, 1995
Summary
Structural studies of Anabaena thioredoxin-2 (Trx-2) reveal its similarity to E. coli thioredoxin. Amino acid substitutions near the active site likely explain Trx-2's unique enzymatic activities and substrate specificity.
Area of Science:
- Biochemistry
- Structural Biology
- Protein Science
Background:
- Thioredoxins are vital reducing agents and protein disulfide reductases found across species.
- Anabaena cyanobacteria possess two distinct thioredoxins, with Trx-2 showing similarities to chloroplast type-f thioredoxin.
- Understanding Trx-2 structure is key to elucidating thioredoxin structure-function relationships.
Purpose of the Study:
- To determine the three-dimensional structure of Anabaena thioredoxin-2 (Trx-2).
- To gain insights into the structure-function relationships of thioredoxins, particularly Trx-2.
- To understand the basis for Trx-2's unique enzymatic activities.
Main Methods:
- X-ray crystallography was used to determine the structure of Anabaena Trx-2.
- Comparative analysis of Trx-2 structure with known thioredoxins, including E. coli thioredoxin.
Main Results:
- Anabaena Trx-2 shares a similar beta-sheet core and alpha-helix arrangement with E. coli thioredoxin.
- A key substitution (Aspartate to Tyrosine) near the active site disulfide ring (31WCGPC35) was observed.
- N-terminal residues of Trx-2 engage in interactions mimicking thioredoxin-protein binding.
Conclusions:
- The overall structure of Trx-2 is conserved among disulfide oxido-reductases.
- Subtle amino acid variations around the protein interaction region likely dictate Trx-2's specific enzymatic functions and substrate discrimination.