Unique evolution of Bivalvia arginine kinases
| Autor: | Tomohiko Suzuki, M. Okamoto, Chisa Mizuta, N. Fujimoto, M. Takeuchi, Kouji Uda |
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| Rok vydání: | 2004 |
| Předmět: |
animal structures
Arginine Molecular Sequence Data Octopodiformes Polymerase Chain Reaction Evolution Molecular Cellular and Molecular Neuroscience Animals Amino Acid Sequence Molecular Biology Conserved Sequence Phylogeny Protein Kinase C Pharmacology chemistry.chemical_classification Sequence Homology Amino Acid biology Molecular mass Kinase Arginine Kinase Cell Biology Arginine kinase biology.organism_classification Ostreidae Enzyme assay Bivalvia Amino acid Enzyme Biochemistry chemistry Mollusca Mutagenesis Site-Directed biology.protein Molecular Medicine Crassostrea Sequence Alignment |
| Zdroj: | Cellular and Molecular Life Sciences (CMLS). 61:110-117 |
| ISSN: | 1420-9071 1420-682X |
| Popis: | The clams Pseudocardium, Solen, Corbicula and Ensis possess a unique form of arginine kinase (AK) with a molecular mass of 80 kDa and an unusual two-domain structure, a result of gene duplication and subsequent fusion. These AKs also lack two functionally important amino acid residues, Asp(62) and Arg(193), which are strictly conserved in other 40-kDa AKs and are assumed to be key residues for stabilizing the substrate-bound structure. However, these AKs show higher enzyme activity. The cDNA-derived amino acid sequences of 40-kDa AKs from the blood clam Scapharca broughtonii and the oyster Crassostrea gigas were determined. While Asp(62) and Arg(193) are conserved in Scapharca AK, these two key residues are replaced by Asn and Lys, respectively, in Crassostrea AK. The native enzyme from Crassostrea and both of the recombinant enzymes show an enzyme activity similar to that of two-domain clam AKs and at least twofold higher than that of other molluskan AKs. Although the replacement of Asp(62) or Arg(193) by Gly in normal AK causes a considerable decrease in V(max) (6-15% of wild-type enzyme) and a two- to threefold increase in K(m) for arginine, the same replacement in Scapharca AK had no pronounced effect on enzyme activity. Together with the observation that bivalve AKs are phylogenetically distinct from other molluskan AKs, these results suggest that bivalve AKs have undergone a unique molecular evolution; the characteristic stabilizing function of residues 62 and 193 has been lost and, consequently, the enzyme shows higher activity than normal. |
| Databáze: | OpenAIRE |
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