PDBsum entry 1fb0

Electron transport

PDB id: 1fb0

Contents

Protein chains

105 a.a. *

Waters ×113

* Residue conservation analysis

PDB id:

1fb0

Name:

Electron transport

Title:

Crystal structure of thioredoxin m from spinach chloroplast (reduced form)

Structure:

Thioredoxin m. Chain: a, b. Fragment: reduced form. Engineered: yes

Source:

Spinacia oleracea. Spinach. Organism_taxid: 3562. Cellular_location: chloroplast. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Tetramer (from PQS)

Resolution:

2.26Å R-factor: 0.198 R-free: 0.235

Authors:

G.Capitani,Z.Markovic-Housley,G.Delval,M.Morris,J.N.Jansonius, P.Schurmann

Key ref:

G.Capitani et al. (2000). Crystal structures of two functionally different thioredoxins in spinach chloroplasts. J Mol Biol, 302, 135-154. PubMed id: 10964566 DOI: 10.1006/jmbi.2000.4006

Date:

14-Jul-00 Release date: 20-Sep-00

Protein chains

P07591  (TRXM_SPIOL) -  Thioredoxin M-type, chloroplastic from Spinacia oleracea

Seq: 181 a.a.

Struc: 105 a.a.

DOI no: 10.1006/jmbi.2000.4006

J Mol Biol 302:135-154 (2000)

PubMed id: 10964566

Crystal structures of two functionally different thioredoxins in spinach chloroplasts.

G.Capitani, Z.Marković-Housley, G.DelVal, M.Morris, J.N.Jansonius, P.Schürmann.

ABSTRACT

Thioredoxins are small ubiquitous proteins which act as general protein disulfide reductases in living cells. Chloroplasts contain two distinct thioredoxins ( f and m) with different phylogenetic origin. Both act as enzyme regulatory proteins but have different specificities towards target enzymes. Thioredoxin f (Trx f), which shares only low sequence identity with thioredoxin m (Trx m) and with all other known thioredoxins, activates enzymes of the Calvin cycle and other photosynthetic processes. Trx m shows high sequence similarity with bacterial thioredoxins and activates other chloroplast enzymes. The here described structural studies of the two chloroplast thioredoxins were carried out in order to gain insight into the structure/function relationships of these proteins. Crystal structures were determined for oxidized, recombinant thioredoxin f (Trx f-L) and at the N terminus truncated form of it (Trx f-S), as well as for oxidized and reduced thioredoxin m (at 2.1 and 2.3 A resolution, respectively). Whereas thioredoxin f crystallized as a monomer, both truncated thioredoxin f and thioredoxin m crystallized as non-covalent dimers. The structures of thioredoxins f and m exhibit the typical thioredoxin fold consisting of a central twisted five-stranded beta-sheet surrounded by four alpha-helices. Thioredoxin f contains an additional alpha-helix at the N terminus and an exposed third cysteine close to the active site. The overall three-dimensional structures of the two chloroplast thioredoxins are quite similar. However, the two proteins have a significantly different surface topology and charge distribution around the active site. An interesting feature which might significantly contribute to the specificity of thioredoxin f is an inherent flexibility of its active site, which has expressed itself crystallographically in two different crystal forms.

Selected figure(s)

Figure 6.
Figure 6. Superimposed stereo C^a traces of the Trx f-L (green), Trx m (blue) and E. coli Trx (red) structures. The active-site residues appear in ball-and-stick mode. The active-site tryptophan 45 of Trx f-L is labelled. Prepared with DINO [Philippsen 1998].

Figure 9.
Figure 9. Stereo view of the superimposed Trx f-L, Trx f-S and Trx m ball-and-stick atomic models in the active site region centered around Asp66 (Trx m). The Trx m model is depicted in yellow and atom colors, the Trx f-S model in green and that of Trx f-L in magenta. Water molecules appear as red spheres. The residues Asp66 (Trx m) and Asn74 (Trx f) are labelled, as are Trp45 of Trx f-L (green label) and of Trx f-S (magenta label). The hydrogen bond between Asp66 and Trp36 in Trx m, as well as that between Asn74 and Asn77 in Trx f are drawn as light cyan lines. Prepared with DINO [Philippsen 1998].

The above figures are reprinted by permission from Elsevier: J Mol Biol (2000, 302, 135-154) copyright 2000.

Figures were selected by an automated process.