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- Title
A robust metallo-oxidase from the hyperthermophilic bacterium Aquifex aeolicus.
- Authors
Fernandes, André T.; Soares, Cláudio M.; Pereira, Manuela M.; Huber, Robert; Grass, Gregor; Martins, Lígia O.
- Abstract
The gene, Aquifex aeolicus AAC07157.1, encoding a multicopper oxidase (McoA) and localized in the genome as part of a putative copper-resistance determinant, has been cloned, over-expressed in Escherichia coli and the recombinant enzyme purified to homogeneity. The purified enzyme shows spectroscopic and biochemical characteristics typical of the well-characterized multicopper oxidase family of enzymes. McoA presents higher specificity ( kcat/ K m) for cuprous and ferrous ions than for aromatic substrates and is therefore designated as a metallo-oxidase. Addition of copper is required for maximal catalytic efficiency. A comparative model structure of McoA has been constructed and a striking structural feature is the presence of a methionine-rich region (residues 321–363), reminiscent of those found in copper homeostasis proteins. The kinetic properties of a mutant enzyme, McoAΔP321-V363, deleted in the methionine-rich region, provide evidence for the key role of this region in the modulation of the catalytic mechanism. McoA has an optimal temperature of 75 °C and presents remarkable heat stability at 80 and 90 °C, with activity lasting for up to 9 and 5 h, respectively. McoA probably contributes to copper and iron homeostasis in A. aeolicus.
- Subjects
OXIDASES; ENZYMES; CLONING; ESCHERICHIA coli; HOMEOSTASIS; COPPER; IRON
- Publication
FEBS Journal, 2007, Vol 274, Issue 11, p2683
- ISSN
1742-464X
- Publication type
Article
- DOI
10.1111/j.1742-4658.2007.05803.x