F
IPR002386

Amicyanin/Pseudoazurin

InterPro entry
Short nameAmicyanin/Pseudoazurin
Overlapping
homologous
superfamilies
 
Cupredoxin (IPR008972)
family relationships

Description

Based on their primary sequences and their unique metabolic role, amicyanins are considered as a distinct subclass of cupredoxins, although they appear to be closely related to the plant plastocyanins
[5]
.

The structure of amicyanin is a β-sandwich, built from nine β-strands. The copper atom is located between three loops on one end of the molecule. Two of these loops contribute the copper ligands. The other three ligands are located on the loop between strands 8 and 9. The structure departs from the general cupredoxin fold in having a 21-residue N-terminal extension, which forms an extra β-strand, and it shows significant differences between strands 5 and 7 (this forms a helix in azurin and an acidic patch in plastocyanin).

Pseudoazurin, also called cupredoxin, is a small, blue periplasmic protein with a single bound copper atom. Pseudoazurin is related to plastocyanins
[6]
. Several examples of pseudoazurin are encoded by a neighbouring gene for, or have been shown to transfer electrons to, copper-containing nitrite reductases (
IPR001287
) of the same species
[4]
.

Pseudoazurin has been identified as an electron donor to the denitrification pathway. For example, pseudoazurin acts as an electron donor to cytochrome c peroxidase and N2OR from Paracoccus pantotrophus
[2]
, and to the copper containing nitrite reductase that catalyzes the second step of denitrification
[1, 3]
. It has been shown that pseudoazurin dramatically enhances the reaction profile of nitrite reduction by Paracoccus pantotrophus cytochrome cd1 and facilitates release of the product nitric oxide. The ability of this small redox protein to interact with a multitude of structurally different partners has been attributed to the hydrophobic character of the binding surface.

References

1.Structure-based engineering of Alcaligenes xylosoxidans copper-containing nitrite reductase enhances intermolecular electron transfer reaction with pseudoazurin. Kataoka K, Yamaguchi K, Kobayashi M, Mori T, Bokui N, Suzuki S. J. Biol. Chem. 279, 53374-8, (2004). View articlePMID: 15475344

2.Direct electron transfer from pseudoazurin to nitrous oxide reductase in catalytic N2O reduction. Fujita K, Hirasawa-Fujita M, Brown DE, Obara Y, Ijima F, Kohzuma T, Dooley DM. J. Inorg. Biochem. 115, 163-73, (2012). View articlePMID: 22910335

3.Crystal structure determinations of oxidized and reduced pseudoazurins from Achromobacter cycloclastes. Concerted movement of copper site in redox forms with the rearrangement of hydrogen bond at a remote histidine. Inoue T, Nishio N, Suzuki S, Kataoka K, Kohzuma T, Kai Y. J. Biol. Chem. 274, 17845-52, (1999). View articlePMID: 10364229

4.Pseudoazurin-nitrite reductase interactions. Impagliazzo A, Krippahl L, Ubbink M. Chembiochem 6, 1648-53, (2005). View articlePMID: 16138306

5.Solution structure of the type 1 blue copper protein amicyanin from Thiobacillus versutus. Kalverda AP, Wymenga SS, Lommen A, van de Ven FJ, Hilbers CW, Canters GW. J. Mol. Biol. 240, 358-71, (1994). View articlePMID: 8035459

6.Crystallization and preliminary X-ray studies on pseudoazurin from Achromobacter cycloclastes IAM1013. Inoue T, Nishio N, Kai Y, Harada S, Ohshiro Y, Suzuki S, Kohzuma T, Shidara S, Iwasaki H. J. Biochem. 114, 761-2, (1993). View articlePMID: 8138527

GO terms

biological process

  • None

cellular component

  • None
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