On the convergent evolution of animal toxins. Conservation of a diad of functional residues in potassium channel-blocking toxins with unrelated structures.
J Biol Chem
; 272(7): 4302-9, 1997 Feb 14.
Article
em En
| MEDLINE
| ID: mdl-9020148
ABSTRACT
BgK is a K+ channel-blocking toxin from the sea anemone Bunodosoma granulifera. It is a 37-residue protein that adopts a novel fold, as determined by NMR and modeling. An alanine-scanning-based analysis revealed the functional importance of five residues, which include a critical lysine and an aromatic residue separated by 6.6 +/- 1.0 A. The same diad is found in the three known homologous toxins from sea anemones. More strikingly, a similar functional diad is present in all K+ channel-blocking toxins from scorpions, although these toxins adopt a distinct scaffold. Moreover, the functional diads of potassium channel-blocking toxins from sea anemone and scorpions superimpose in the three-dimensional structures. Therefore, toxins that have unrelated structures but similar functions possess conserved key functional residues, organized in an identical topology, suggesting a convergent functional evolution for these small proteins.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Venenos de Cnidários
/
Bloqueadores dos Canais de Potássio
/
Evolução Biológica
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1997
Tipo de documento:
Article