1r7h: Difference between revisions

[[Image:1r7h.jpg|left|200px]]<br /><applet load="1r7h" size="350" color="white" frame="true" align="right" spinBox="true"  

NrdH-redoxins constitute a family of small redox proteins, which contain a conserved CXXC sequence motif, and are characterized by a glutaredoxin-like amino acid sequence but a thioredoxin-like activity profile. Here we report the structure of Corynebacterium ammoniagenes NrdH at 2.7 A resolution, determined by molecular replacement using E. coli NrdH as model. The structure is the first example of a domain-swapped dimer from the thioredoxin family. The domain-swapped structure is formed by an inter-chain two-stranded anti-parallel beta-sheet and is stabilized by electrostatic interactions at the dimer interface. Size exclusion chromatography, and MALDI-ESI experiments revealed however, that the protein exists as a monomer in solution. Similar to E. coli NrdH-redoxin and thioredoxin, C. ammoniagenes NrdH-redoxin has a wide hydrophobic pocket at the surface that could be involved in binding to thioredoxin reductase. However, the loop between alpha2 and beta3, which is complementary to a crevice in the reductase in the thioredoxin-thioredoxin reductase complex, is the hinge for formation of the swapped dimer in C. ammoniagenes NrdH-redoxin. C. ammoniagenes NrdH-redoxin has the highly conserved sequence motif W61-S-G-F-R-P-[DE]67 which is unique to the NrdH-redoxins and which determines the orientation of helix alpha3. An extended hydrogen-bond network, similar to that in E. coli NrdH-redoxin, determines the conformation of the loop formed by the conserved motif.

1R7H is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Corynebacterium_ammoniagenes Corynebacterium ammoniagenes]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1R7H OCA].  

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