1faa
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CRYSTAL STRUCTURE OF THIOREDOXIN F FROM SPINACH CHLOROPLAST (LONG FORM)
OverviewOverview
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.
About this StructureAbout this Structure
1FAA is a Single protein structure of sequence from Spinacia oleracea. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of two functionally different thioredoxins in spinach chloroplasts., Capitani G, Markovic-Housley Z, DelVal G, Morris M, Jansonius JN, Schurmann P, J Mol Biol. 2000 Sep 8;302(1):135-54. PMID:10964566
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