1FB0

CRYSTAL STRUCTURE OF THIOREDOXIN M FROM SPINACH CHLOROPLAST (REDUCED FORM)

Summary for 1FB0

• Entry DOI: 10.2210/pdb1fb0/pdb
• Related: 1F9M 1FAA 1FB6
• Descriptor: THIOREDOXIN M (2 entities in total)
• Functional Keywords: electron transport
• Biological source: Spinacia oleracea (spinach)
• Cellular location: Plastid, chloroplast: P07591
• Total number of polymer chains: 2
• Total formula weight: 23586.87

Authors

Capitani, G.,Markovic-Housley, Z.,DelVal, G.,Morris, M.,Jansonius, J.N.,Schurmann, P. (deposition date: 2000-07-14, release date: 2000-09-20, Last modification date: 2024-02-07)

Primary citation

Capitani, G.,Markovic-Housley, Z.,DelVal, G.,Morris, M.,Jansonius, J.N.,Schurmann, P.
Crystal structures of two functionally different thioredoxins in spinach chloroplasts.
J.Mol.Biol., 302:135-154, 2000

PubMed 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.

PubMed: 10964566
DOI: 10.1006/jmbi.2000.4006

Experimental method

X-RAY DIFFRACTION (2.26 Å)