Journal article
Structure of Hordeum vulgare NADPH-dependent thioredoxin reductase 2. Unwinding the reaction mechanism
Thioredoxins (Trxs) are protein disulfide reductases that regulate the intracellular redox environment and are important for seed germination in plants. Trxs are in turn regulated by NADPH-dependent thioredoxin reductases (NTRs), which provide reducing equivalents to Trx using NADPH to recycle Trxs to the active form.
Here, the first crystal structure of a cereal NTR, HvNTR2 from Hordeum vulgare (barley), is presented, which is also the first structure of a monocot plant NTR. The structure was determined at 2.6 A resolution and refined to an R (cryst) of 19.0% and an R (free) of 23.8%. The dimeric protein is structurally similar to the structures of AtNTR-B from Arabidopsis thaliana and other known low-molecular-weight NTRs.
However, the relative position of the two NTR cofactor-binding domains, the FAD and the NADPH domains, is not the same. The NADPH domain is rotated by 25 degrees and bent by a 38% closure relative to the FAD domain in comparison with AtNTR-B. The structure may represent an intermediate between the two conformations described previously: the flavin-oxidizing (FO) and the flavin-reducing (FR) conformations.
Here, analysis of interdomain contacts as well as phylogenetic studies lead to the proposal of a new reaction scheme in which NTR-Trx interactions mediate the FO to FR transformation.
Language: | English |
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Publisher: | International Union of Crystallography |
Year: | 2009 |
Pages: | 932-941 |
ISSN: | 13990047 and 09074449 |
Types: | Journal article |
DOI: | 10.1107/S0907444909021817 |
ORCIDs: | Svensson, Birte |
NADPH NADPH-dependent thioredoxin reductases barley disulfide oxidoreductases germination redox regulation seed development
Allosteric Regulation Allosteric Site Arabidopsis Arabidopsis Proteins Crystallization Crystallography, X-Ray FMN Reductase Germination Hordeum NTRB protein, Arabidopsis Oxidation-Reduction Protein Conformation Protein Interaction Domains and Motifs Structural Homology, Protein Thioredoxin Reductase 2 Thioredoxin-Disulfide Reductase