2WHD

Barley NADPH-dependent thioredoxin reductase 2

Summary for 2WHD

• Entry DOI: 10.2210/pdb2whd/pdb
• Descriptor: THIOREDOXIN REDUCTASE, FLAVIN-ADENINE DINUCLEOTIDE, CITRATE ANION, ... (4 entities in total)
• Functional Keywords: redox-active center, disulfide oxidoreductase, oxidoreductase, seed development, redox regulation, ntr, germination, flavoprotein
• Biological source: Hordeum vulgare (BARLEY)
• Total number of polymer chains: 2
• Total formula weight: 76324.56

Authors

Kirkensgaard, K.G.,Hagglund, P.,Finnie, C.,Svensson, B.,Henriksen, A. (deposition date: 2009-05-04, release date: 2009-09-01, Last modification date: 2024-10-23)

Primary citation

Kirkensgaard, K.G.,Hagglund, P.,Finnie, C.,Svensson, B.,Henriksen, A.
Structure of Hordeum Vulgare Nadph-Dependent Thioredoxin Reductase 2. Unwinding the Reaction Mechanism.
Acta Crystallogr.,Sect.D, 65:932-, 2009

PubMed Abstract: 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.

PubMed: 19690371
DOI: 10.1107/S0907444909021817

Experimental method

X-RAY DIFFRACTION (2.6 Å)